GELS, methods of making GELS, and uses thereof

Abstract

In one aspect, the disclosure relates to relates to methods for producing an aerogel comprising: mixing together a polymeric material, a solvent, and an additional agent to form a slurry; homogenizing the slurry to form a hydrogel; aerating the hydrogel to form a foam; freezing the foam at a temperature of about −90 °C to about −10 °C; and freeze-drying the foam at a pressure of about 0.1 mbar to about 1 mbar and a temperature of about −90 °C to about −20 °C to form an aerogel. In another aspect, the disclosure relates to compositions comprising: a biopolymer, a biopolymer material, or a combination thereof; and an additional agent selected from a plasticizer, a crosslinking agent, or a combination thereof. This abstract is intended as a scanning tool for purposes of searching in the particular art and is not intended to be limiting of the present disclosure.

Description

GELS, METHODS OF MAKING GELS, AND USES THEREOFCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This Application claims the benefit of and priority to U.S. Provisional Application No. 63 / 655,269, filed on June 3, 2024 which is incorporated herein by reference in its entirety.BACKGROUND

[0002] Research into functional coatings is a growing area in textile engineering, with the goal of broadening the spectrum of aerogel applications into thermal insulation and superabsorbent functional textile coatings in textiles. Aerogels are well known for being extremely lightweight, with high porosity, low density, and high specific surface area. Industrial production of aerogels using conventional methods suffer from issues such as relatively high production cost, due at least in part to the use of large amounts of solvents and high energy requirements for drying during aerogel production. Despite advances in aerogels and aerogel production, there remains a lack of aerogels and aerogel formation methods that are relatively environmentally sustainable and cost-efficient. These needs and other needs are satisfied by the present disclosure.SUMMARY

[0003] In accordance with the purpose(s) of the disclosure, as embodied and broadly described herein, the disclosure, in one aspect, relates to a method for producing an aerogel, comprising: mixing together a polymeric material, a solvent, and an additional agent to form a slurry, wherein the additional agent is selected from a plasticizer, a crosslinking agent, or a combination thereof; homogenizing the slurry to form a hydrogel; aerating the hydrogel to form a foam; freezing the foam at a temperature of about -90 °C to about -10 °C; and freeze-drying the foam at a pressure of about 0.1 mbar to about 1 mbar and a temperature of about -90 °C to about -20 °C to form an aerogel. In a further aspect, the polymeric material comprises at least one biopolymer, at least one biopolymer material, or a combination thereof.

[0004] In another aspect, the disclosure relates to a method for producing an aerogel, comprising: mixing together a polymeric material, a solvent, and an additional agent to form a slurry, wherein the additional agent is selected from a plasticizer, chitosan, or a combination thereof; homogenizing the slurry to form a hydrogel; aerating the hydrogel to form a foam; freezing the foam at a temperature of about -90 °C to about -10 °C for about 0.1 hours to about 12.0 hours; and freeze-drying the foam at a pressure of about 0.1 mbar to about 1 mbar and a temperature of about -90 °C to about -20 °C to form an aerogel; wherein the polymeric material comprises at least one biopolymer, at least one biopolymer material, or a combination thereof.

[0005] In another aspect, the disclosure relates to a composition comprising: a biopolymer, a biopolymer material, or a combination thereof; and an additional agent selected from a plasticizer, a crosslinking agent, or a combination thereof; wherein the plasticizer comprisesan anionic cellulose derivative, a nonionic cellulose derivative, glycerol, sorbitol, xylitol, polyethylene glycol, a natural oil, lactic acid, a derivative of starch, triethyl citrate, diethyl phthalate, propylene glycol, or a combination thereof; and wherein the crosslinking agent comprises chitosan, phytic acid, citric acid, tannic acid, calcium chloride, glutaraldehyde, transglutaminase, sodium alginate, lignin, a polyphenol, genipin, or a combination thereof.

[0006] In another aspect, the disclosure relates to a composition comprising: a biopolymer, a biopolymer material, or a combination thereof; and an additional agent selected from a plasticizer, a crosslinking agent, or a combination thereof; wherein the plasticizer comprises an anionic cellulose derivative, a nonionic cellulose derivative, or a combination thereof; and wherein the crosslinking agent comprises chitosan, phytic acid, citric acid, tannic acid, calcium chloride, glutaraldehyde, transglutaminase, sodium alginate, lignin, a polyphenol, genipin, or a combination thereof.

[0007] Other systems, methods, features, and advantages of the present disclosure will be or become apparent to one with skill in the art upon examination of the following drawings and detailed description. It is intended that all such additional systems, methods, features, and advantages be included within this description, be within the scope of the present disclosure, and be protected by the accompanying claims. In addition, all optional and preferred features and modifications of the described aspects are usable in all aspects of the disclosure taught herein. Furthermore, the individual features of the dependent claims, as well as all optional and preferred features and modifications of the described aspects are combinable and interchangeable with one another.BRIEF DESCRIPTION OF THE FIGURES

[0008] Many aspects of the present disclosure can be better understood with reference to the following drawings. The components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present disclosure. Moreover, in the drawings, like reference numerals designate corresponding parts throughout the several views.

[0009] FIGS. 1A and 1B show representative diagrams of thermal regulation across 3D sandwich structures illustrating a sweat release (FIG. 3D) and a cooling (FIG. 3E) effect.

[0010] FIGS. 1C and 1D show images depicting representative initial aerogel samples: nanofibrillated cellulose (NFC) (FIG. 1A) and nanocrystalline cellulose (NCC) (FIG. 1 B).

[0011] FIGS. 1 E and 1 F show representative pore size distribution analyses using JMP software of initial aerogel samples: nanofibrillated cellulose (NFC) (FIG. 1C) and nanocrystalline cellulose (NCC) (FIG. 1 D).

[0012] FIG. 2A shows representative apparent density of the 3D structures combined (cotton and aerogel) with different thicknesses aerogel layers: 2C - two layers of cotton; 2C+NCC - two layers of cotton with middle aerogel layer; and 2C+NFC - two layers of cotton with NFC middle aerogel layer.

[0013] FIG. 2B shows representative dry thermal conductivity, intrinsic thermal resistance (Ref) values of a fabric test specimen only at different thickness of NCC aerogel middle layers: 20 - two layers of cotton and 2C+NCC - two layers of cotton with middle aerogel layer.

[0014] FIGS. 3A-3C show illustrations (top) and images (bottom) of different cotton aerogel 3D units: 2C+NCC - two layers of cotton with 1mm NCC aerogel (FIG. 3A); 2C+NCC+PCM - two layers of Cotton with 1mm NCC aerogel and filled with phase-changing materials (PCM) (filled aerogel, FIG. 3B); and 2C+NCC+Silica aerogel - two layers of cotton with 1mm NCC incorporated with silica aerogel (hybrid aerogel, FIG. 3C).

[0015] FIG. 4A shows representative Ref at equilibrium of NCC at different loadings of PCM in room temperature.

[0016] FIG. 4B shows representative Ref at equilibrium of NCC at different loadings of PCM at body temperature.

[0017] FIG. 4C shows Ref values at thermal equilibrium in room temperature vs. body temperature.

[0018] FIG. 4D shows data demonstrating the extent of the PCM effect in aerogels.

[0019] FIG. 5A shows representative Ref values of Cotton+nanocellulose (NC)+Silicon+PCM hybrid aerogel with different PCM and silica aerogel loadings in middle NC aerogel layer: 2C - two cotton layers.

[0020] FIG. 5B shows representative Ref values at equilibrium.

[0021] FIG. 6A shows representative FT-IR of different selected lignocellulosic sources.

[0022] FIG. 6B shows representative moisture content of selected lignocellulosic sources.

[0023] FIG. 6C shows representative Ref values of selected lignocellulosic aerogel and cotton 3D structures.

[0024] FIG. 7A shows images depicting hydrogels of different lignocellulosic sources for aerogels and a listing of different lignocellulosic sources, densities and porosity.

[0025] FIGS. 7B and 7C show water absorbency (FIG. 7B) and oil absorbency (FIG. 7C) of different aerogels.

[0026] FIG. 8A show a representative 3D cross-section of a 2C+NC aerogel sandwich structure.

[0027] FIG. 8B shows a representative SEM image of the 3D cross-section of a 2C+NC aerogel sandwich structure at *95 magnification.

[0028] FIG. 8C shows representative interfacial adhesion and layering of a cross-section of a 2C+NC aerogel sandwich structure at x 150 magnification.

[0029] FIGS. 9A and 9B show a representative SEM image depicting structural porosity of an NC aerogel through cross-section at xiso magnification (FIG. 9A) and a representative porometer functional porosity analysis of the NC aerogel cross-section (FIG. 9B).

[0030] FIGS. 9C and 9D show a representative SEM image depicting structural porosity of a filled aerogel (NC+PCM) through cross-section at x200 magnification (FIG. 9C) and arepresentative porometer functional porosity analysis of the filled aerogel (NC+PCM) crosssection (FIG. 9D).

[0031] FIGS. 9E and 9F show a representative SEM image depicting structural porosity of a hybrid aerogel (NC+PCM+Si) through cross-section at *150 magnification (FIG. 9E) and a representative porometer functional porosity analysis of the hybrid aerogel (NC+PCM+Si) cross-section (FIG. 9F).

[0032] FIGS. 10A and 10B show a representative SEM image depicting structural porosity of a cotton noil aerogel through cross-section at *150 magnification (FIG. 10A) and a representative porometer functional porosity analysis of the cotton noil aerogel cross-section (FIG. 10B).

[0033] FIGS. 10C and 10D show a representative SEM image depicting structural porosity of a sawdust aerogel through cross-section at *150 magnification (FIG. 10C) and a representative porometer functional porosity analysis of the sawdust aerogel cross-section (FIG. 10D).

[0034] FIGS. 10E and 10F show a representative SEM image depicting structural porosity of a hemp aerogel through cross-section at x 150 magnification (FIG. 10E) and a representative porometer functional porosity analysis of the hemp aerogel cross-section (FIG. 10F).

[0035] FIGS. 11A-11C show top views and side views of representative silk aerogels with decreasing concentrations of silk: 28 ml (FIG. 11A), 25 ml (FIG. 11 B), and 20 ml (FIG. 11C).

[0036] FIGS. 12A-12C show top views and side views of representative silk-based algae aerogels with decreasing concentrations of algae: 7 ml (FIG. 12A), 5 ml (FIG. 12B), and 3 ml (FIG. 12C).

[0037] FIGS. 13A-13G show top views and side views of representative aerogels with 2% nano fibrillated cellulose (FIG. 13A); 2% noil (FIG. 13B); 2% hemp (FIG. 13C); 2%(1 :1 hemp and lignin) (FIG. 13D); 2% (15% lignin: 85 % hemp) (FIG. 13E); 2% (10 % lignin:90% hemp) (FIG. 13F); and g 2% (Chitosan) (FIG. 13G).

[0038] FIGS. 14A-14G show top views and side views of representative 2% hemp and / or lignin-based aerogel aerogels with 0% lignin, 100% hemp (FIG. 14A); 2.5% lignin, 97.5% hemp (FIG. 14B); 5% lignin, 95% hemp (FIG. 140); 10% lignin, 90% hemp (FIG. 14D); 15% lignin, 85% hemp (FIG. 14E); and 50% lignin, 50% hemp (FIG. 14F).

[0039] FIG. 15A shows an image of a representative banana aerogel textile prototype.

[0040] FIG. 15B shows an image depicting an aerogel made from knife mill banana microfiber (BKM, left) and an aerogel made from ball mill banana microfiber (BBM, right).

[0041] FIGS. 15C and 15D show oil absorption capacity (FIG. 150) and oil retention capacity (FIG. 15D) of the banana aerogel.

[0042] FIG. 16 shows a representative aerogel synthesis process from banana stalk waste.

[0043] FIG. 17 shows the molecular structure of lignin.

[0044] FIG. 18 shows a representative aerogel modification using photocatalytic nanoparticles.

[0045] FIGS. 19A-19C show top views and side views of representative aerogels modified using photocatalytic nanoparticles: 2% banana aerogel with 2% nanoparticles (FIG. 19A); 2% banana aerogel with 4% nanoparticles (FIG. 19B); and 2% banana aerogel with 6% nanoparticles (FIG. 19C).

[0046] FIGS. 20A-20C show images depicting the qualitative test of the interaction and stability of a representative banana fiber aerogel in water (FIG. 20A), after 1 minute and force applied (FIG. 20B), and taken out of the water (FIG. 20C).

[0047] FIGS. 20D-20F show images depicting the qualitative test of the interaction and stability of a representative banana fiber aerogel in motor oil and water (FIG. 20D), after 4 minutes (FIG. 20E), and taken out of the mixture (FIG. 20F).

[0048] FIGS. 20G-20I show images depicting the qualitative test of the interaction and stability of a representative 1% in situ chitosan banana fiber aerogel in water (FIG. 20G), after 1 minute and force applied (FIG. 20H), and taken out of the water (FIG. 20I).

[0049] FIGS. 20J-20L show images depicting the qualitative test of the interaction and stability of a representative 1% in situ chitosan banana fiber aerogel in motor oil and water (FIG. 20J), after 4 minutes (FIG. 20K), and taken out of the mixture (FIG. 20L).

[0050] FIGS. 20M-200 show images depicting the qualitative test of the interaction and stability of a representative 1 % in situ chitosan banana fiber aerogel (heat-treated at 150 °C) in water (FIG. 20M), after 1 minute and force applied (FIG. 20N), and taken out of the water (FIG. 200).

[0051] FIGS. 20P-20R show images depicting the qualitative test of the interaction and stability of a representative 1 % in situ chitosan banana fiber aerogel (heat-treated at 150 °C) in motor oil and water (FIG. 20P), after 4 minutes (FIG. 20Q), and taken out of the mixture (FIG. 20R).

[0052] FIGS. 21 A and 21 B show a representative in-situ 2% banana fiber 1% chitosan heat- treated aerogel where the chitosan matrix could be observed with banana fiber making the compact aerogel matrix.

[0053] FIGS. 21C-21 E show an image depicting the porous nature of the representative in- situ 2% banana fiber 1 % chitosan heat-treated aerogel using morphological analysis at 50X.

[0054] FIG. 21 F shows an image depicting the representative in-situ 2% banana fiber 1% chitosan heat-treated aerogel at 20X.

[0055] FIG. 22 shows an image depicting a representative banana aerogel encased in a thin layer of polypropylene.

[0056] FIG. 23 shows a flowchart of a representative algae aerogel preparation process.

[0057] FIGS. 24A and 25B show oil sorption capacity (FIG. 24A) and oil retention capacity over 24 hours (FIG. 24B) of a representative algae-based aerogel: 10P (10 ml 2% w / v pulp hydrogel); 2C8P(2ml Algae +2ml 2% w / v pulp hydrogel); 4C6P (4ml Algae +6ml 2% w / v pulp hydrogel); 6C4P (6ml Algae +4ml 2% w / v pulp hydrogel).

[0058] FIG. 25 shows thermogravimetric analysis curves of different representative aerogels.

[0059] FIGS. 26A-26C show flow charts of aerogel freezing studies using different containers.

[0060] FIG. 27 shows pore size distributions of a representative banana and silk hybrid aerogel in aluminum, glass, and polystyrene containers.

[0061] FIG. 28 shows a representative methodology for producing an in situ chitosan / NFC / wool composite aerogel.

[0062] FIGS. 29A-29D show an in situ chitosan-NFC / wool aerogel with: 0.5 wt% chitosan / 2 wt% NFC (FIG. 29A); 0.5 wt% chitosan / 1.5 wt% NFC / 0.5 wt% wool (FIG. 29B); 0.5 wt% chitosan / 1 wt% NFC / 1 wt% wool (FIG. 29C); and 0.5 wt% chitosan / 0.5 wt% NFC / 1.5 wt% wool (FIG. 29D).

[0063] FIG. 30 shows stress-strain curves for various representative in situ chitosan- NFC / wool composite aerogels.

[0064] FIG. 31 shows thermogravimetric analysis curves for various representative in situ chitosan-NFC / wool composite aerogels.

[0065] FIG. 32 shows a comparative thermal resistance of representative cotton fabric and representative in situ chitosan-NFC / wool aerogels.

[0066] FIG. 33 shows a representative process of an absorbent capacity test for in situ chitosan-NFC / glycerol composite aerogel.

[0067] FIGS. 34A-34C shows a top view (FIG. 34A) and flexure side views (FIG. 34B and FIG. 34C) of a representative in situ 0.5 wt% chitosan - 1 wt% NFC / 0.25 wt% glycerol aerogel.

[0068] FIGS. 35A and 35B show dispersion of representative in situ chitosan-phytic acid solutions at varying ratios (based on 0.5% chitosan) after stirring for a couple of hours (FIG. 35A) and after resting at least 30 minutes (FIG. 35B).

[0069] FIGS. 36A and 36B show flammability tests for representative in situ 0.5 wt% chitosan I 1 wt% NFC (FIG. 36A) and in situ 0.5 wt% chitosan I 1 wt% NFC I 0.125 wt% phytic acid (FIG. 36B).

[0070] FIG. 37 shows an image depicting personal protective equipment.

[0071] FIG. 38 shows an image depicting a banana tree with various parts identified.

[0072] FIG. 39 shows a representative aerogel synthesis process.

[0073] FIGS. 40A and 40B show the pore size distribution of 10% sodium bicarbonate (NaBC) treated banana-chitosan aerogel (BCA) (FIG. 40A) and 10% NaBC treated banana-silk- chitosan aerogel (BSCA) (FIG. 40B).

[0074] FIGS. 41 A and 41 B show pictures depicting a banana aerogel textile prototype (FIG. 41 A) and BKM (left) and BBM (right) aerogels (FIG. 41 B).

[0075] FIGS. 41 C and 41 D show oil absorption capacity (FIG. 41 C) and oil retention capacity (FIG. 15D) of the BKM and BBM aerogels.

[0076] FIGS. 42A and 42B show oil absorption capacity (FIG. 42A) and oil retention capacity (FIG. 42B) of the 1% banana 1 % silk in situ chitosan treated hybrid (BS_Treated) and 2 % banana in situ chitosan treated aerogel (B_treated).

[0077] FIGS. 43A-43D show visual representations of aerogel flame retardant behavior for a 2% banana aerogel (FIG. 43A); a 1% banana 1% silk aerogel (FIG. 43B); a 2% banana, treated aerogel (FIG. 43C); and a % banana 1% silk, treated aerogel (FIG. 43D).

[0078] FIGS. 44A-44C shows a representative product obtained in different steps: after 4 days mixing with oxide nanocrystal (FIG. 44A); after 24h at -80°C (freezing in freezer) (FIG. 44B); after 48h in freeze drying (1MP, -80 °C) (FIG. 44C).

[0079] FIGS. 45A and 45B show representative diffuse reflectance spectroscopy analyses of pure aerogel (FIG. 45A) and nanoparticle-encapsulated aerogel (FIG. 45B).

[0080] FIGS. 46A and 46B show representative FT-IR spectroscopy results for pure aerogel (FIG. 46A) and nanoparticle-encapsulated aerogel (FIG. 46B).

[0081] FIGS. 47A-47F show representative field emission scanning electron microscopy (FESM) images of pure aerogel: surface of A(2%) (FIG. 47A), A(1%) (FIG. 47B), and A(0.5%) (FIG. 47C) and cross section of A(2%) (FIG. 47D), A(1 %) (FIG. 47E), and A(0.5%) (FIG. 47F).

[0082] FIGS. 48A-48F show representative FESM images of nanoparticle-encapsulated aerogel: surface of A(2%)@NP (FIG. 48A), A(1%)@NP (FIG. 48B), and A(0.5%)@NP (FIG. 48C) and cross section of A(2%)@NP (FIG. 48D), A(1 %)@NP (FIG. 48E), and A(0.5%)@NP (FIG. 48F).

[0083] FIGS. 49A-49F show representative energy-dispersive X-ray spectroscopy (EDS analyses of nanoparticle-encapsulated aerogel: surface of A(2%)@NP (FIG. 49A), A(1 %)@NP (FIG. 49B), and A(0.5%)@NP (FIG. 49C).

[0084] FIGs. 50A and 50B show representative thermal gravimetric analyses of pure aerogel (FIG. 50A) and nanoparticle-encapsulated aerogel (FIG. 50B).

[0085] FIGS. 51 A and 51 B show representative spectral power distributions (SPD) for LED light (FIG. 51 A) and xenon lamp (FIGS. 51 B).

[0086] FIGS. 52A and 52B show different view of a lab-made photocatalytic box.

[0087] FIGS. 53A-53C show photocatalytic degradation of methylene blue (MB) in a neutral environment with different materials.

[0088] FIGS. 53D and 53E show results from kinetic studies.

[0089] FIGS. 54A-54D show photocatalytic degradation of MB in a neutral environment with different materials.

[0090] FIGS. 54E and 53F show results from kinetic studies.

[0091] FIGS. 55A-55D show photocatalytic degradation of reactive dye in acidic (FIG. 55A), neutral (FIG. 55A), and basic environments (FIG. 55A); photodecomposition efficiency of NP(Sr) (FIG. 55D) and photocatalytic degradation kinetics of A(1%)@NP(1 %) under visible light (FIG. 55E).

[0092] FIGS. 55F-55H show images depicting representative samples obtained from the photocatalytic degradation of RD120 in acidic (FIG. 55F), neutral (FIG. 55G), and basic environments (FIG. 55H).

[0093] FIGs. 56A-56G show stability tests of the cellulose composite in RD120 solution with different pH levels: pH=2 (FIG. 56A), pH=4 (FIG. 56B), pH=6 (FIG. 56C), pH=7 (FIG. 56D), pH=8 (FIG. 56E), pH=10 (FIG. 56F), and pH=12 (FIG. 56G). In each figure, from left to right is A(0.5%)@NP, A(1%)@NP, and A(2%)@NP.

[0094] Additional advantages of the disclosure will be set forth in part in the description which follows, and in part will be obvious from the description, or can be learned by practice of the disclosure. The advantages of the disclosure will be realized and attained by means of the elements and combinations particularly pointed out in the appended claims. It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the disclosure, as claimed.DETAILED DESCRIPTION

[0095] This disclosure is not limited to particular embodiments described, and as such may, of course, vary. The terminology used herein serves the purpose of describing particular embodiments only, and is not intended to be limiting, since the scope of the present disclosure will be limited only by the appended claims.

[0096] Where a range of values is provided, each intervening value, to the tenth of the unit of the lower limit unless the context clearly dictates otherwise, between the upper and lower limit of that range and any other stated or intervening value in that stated range, is encompassed within the disclosure. The upper and lower limits of these smaller ranges may independently be included in the smaller ranges and are also encompassed within the disclosure, subject to any specifically excluded limit in the stated range. Where the stated range includes one or both of the limits, ranges excluding either or both of those included limits are also included in the disclosure.

[0097] Embodiments of the present disclosure will employ, unless otherwise indicated, techniques of organic chemistry, biochemistry, material chemistry, and the like, which are within the skill of the art. Such techniques are explained fully in the literature.

[0098] The following examples are put forth so as to provide those of ordinary skill in the art with a complete disclosure and description of how to perform the methods and use the compositions and compounds disclosed and claimed herein. Efforts have been made to ensure accuracy with respect to numbers (e.g., amounts, temperature, etc.), but some errors and deviations should be accounted for. Unless indicated otherwise, parts are parts by weight, temperature is in °C, and pressure is at or near atmospheric. Standard temperature and pressure are defined as 20 °C and 1 atmosphere.

[0099] It should be noted that ratios, concentrations, amounts, and other numerical data may be expressed herein in a range format. It is to be understood that such a range format is used for convenience and brevity, and thus, should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if eachnumerical value and sub-range is explicitly recited. To illustrate, a concentration range of “about 0.1 percent to about 5 percent” should be interpreted to include not only the explicitly recited concentration of about 0.1 weight percent to about 5 weight percent but also include individual concentrations (e.g., 1 percent, 2 percent, 3 percent, and 4 percent) and the subranges (e.g., 0.5 percent, 1.1 percent, 2.2 percent, 3.3 percent, and 4.4 percent) within the indicated range. The term “about” can include traditional rounding according to significant figures of the numerical value. In addition, the phrase “about ‘x’ to ‘y’” includes “about ‘x’ to about ‘y’”.

[0100] Furthermore, the terms “about”, “approximate”, “at or about”, and “substantially” as used herein mean that the amount or value in question can be the exact value or a value that provides equivalent results or effects as recited in the claims or taught herein. That is, it is understood that amounts, sizes, formulations, parameters, and other quantities and characteristics are not and need not be exact, but may be approximate and / or larger or smaller, as desired, reflecting tolerances, conversion factors, rounding off, measurement error and the like, and other factors known to those of skill in the art such that equivalent results or effects are obtained. In some circumstances, the value that provides equivalent results or effects cannot be reasonably determined. In such cases, it is generally understood, as used herein, that “about” and “at or about” mean the nominal value indicated ±10% variation unless otherwise indicated or inferred. In general, an amount, size, formulation, parameter or other quantity or characteristic is “about,” “approximate,” or “at or about” whether or not expressly stated to be such. It is understood that where “about,” “approximate,” or “at or about” is used before a quantitative value, the parameter also includes the specific quantitative value itself, unless specifically stated otherwise.

[0101] Before the embodiments of the present disclosure are described in detail, it is to be understood that, unless otherwise indicated, the present disclosure is not limited to particular materials, reagents, reaction materials, manufacturing processes, dimensions, frequency ranges, applications, or the like, as such can vary. It is also to be understood that the terminology used herein is for purposes of describing particular embodiments only, and is not intended to be limiting. It is also possible in the present disclosure that steps can be executed in different sequence, where this is logically possible. It is also possible that the embodiments of the present disclosure can be applied to additional embodiments involving measurements beyond the examples described herein, which are not intended to be limiting. It is furthermore possible that the embodiments of the present disclosure can be combined or integrated with other measurement techniques beyond the examples described herein, which are not intended to be limiting.

[0102] It should be noted that, as used in the specification and the appended claims, the singular forms “a,” “an,” and “the” include plural referents unless the context clearly dictates otherwise. Thus, for example, reference to “a support” includes a plurality of supports. In thisspecification and in the claims that follow, reference will be made to a number of terms that shall be defined to have the following meanings unless a contrary intention is apparent.

[0103] Each of the applications and patents cited in this text, as well as each document or reference cited in each of the applications and patents (including during the prosecution of each issued patent; “application cited documents”), and each of the PCT and foreign applications or patents corresponding to and / or claiming priority from any of these applications and patents, and each of the documents cited or referenced in each of the application cited documents, are hereby expressly incorporated herein by reference. Further, documents or references cited in this text, in a Reference List before the claims, or in the text itself; and each of these documents or references (“herein cited references”), as well as each document or reference cited in each of the herein-cited references (including any manufacturer’s specifications, instructions, etc.) are hereby expressly incorporated herein by reference.

[0104] Prior to describing the various embodiments, the following definitions are provided and should be used unless otherwise indicatedA. DEFINITIONS

[0105] As used herein, a “gel” refers to a crosslinked polymer network (formed via chemical or physical crosslinking) that is swollen by absorbing a fluid (liquid or gas). Gels exhibit no flow when in a steady state. The properties of a gel depend on the interactions and interaction parameters of the polymer network with the fluid (e.g., a solvent). Gels can undergo phase transitions and have variations in discontinuous volume phase as a response to changes in temperature, solvent composition, pH, ionic composition, or applied electric field.

[0106] “Gel”, as used herein, also includes materials with a solid phase dispersed or suspended in a liquid (e.g., a solvent such as water or an organic solvent), where the solid phase includes a two-phase elastic colloidal material. The primary component of the solid phase of a gel can be a homopolymer or a heteropolymer of natural, biobased, bio- compostable, or synthetic origin. The colloidal material of the solid phase of a gel can include polymeric particles or fibers. These polymeric particles or fibers can be nanoscale or submicroscale in size.

[0107] The “solvent” or “solvent phase” of a gel refers to the ambient fluid within it, whose form can be a liquid or gas. Prefixes such as “aero,” “organo,” “hydro,” and variations are understood to reference the ambient fluid in a cross-linked gel matrix and primary component of the gel material.

[0108] As used herein, “hydrogel” represents a network of polymeric and / or cellulosic material as a colloidal gel dispersed in a carrier, such as water.

[0109] As used herein, “aerogel” refers to a gel derived from the further processing of a hydrogel or other gel material by removing the solvent phase while retaining the 3D network structure of the solid phase to form a highly porous structure. Removing the solvent phase from a gel material to form an aerogel can include drying methods such as supercritical dryingor freeze-drying. Aerogels are a highly porous, solid, aerated foam composed of a network of interconnected polymeric nanostructures. Aerogels have an apparent density typically between 0.003 g / cm3and 0.5 g / cm3, a high porosity (non-solid volume) of at least 50% and up to about 94%, a high specific surface area (e.g., at least 200 m2 / g), and a pore size distribution of meso- or micro-porosity that ranges from 0.6 nm to 20 nm.

[0110] Aerogel porosity microstructure is characterized herein in part by pore size distributions. As used herein, “microporous” aerogels refer to aerogels with pore size distributions of less than 2 nm, “mesoporous” aerogels refer to aerogels with pore size distributions of from 2 nm to about 50 nm, and “mixed-porous” aerogels refer to aerogels with random pore size distributions.

[0111] As used herein “biopolymer” refers to naturally occurring polymers comprising repetitive monomeric units that are covalently bonded together to form larger molecules. They can be obtained from renewable sources such as plants, animals, and microorganisms. Examples of biopolymers include lignin, cellulose, hemicellulose, nanocellulose, and silk fibroin.

[0112] As used herein “biopolymer material” refers to a naturally occurring material comprised of at least two biopolymers. Biopolymer materials can be obtained from renewable sources such as plants, animals, and microorganisms. Examples of biopolymer materials include lignocellulosic biomass and algal biomass.

[0113] As used herein, “lignocellulosic biomass” refers to a plant or plant-based material that is composed primarily of cellulose, hemicellulose, and lignin.

[0114] As used herein, the term “derivative” refers to a compound having a structure derived from the structure of a parent compound (e.g., cellulose) and whose structure is sufficiently similar to the parent compound and based upon that similarity, would be expected by one skilled in the art to exhibit the same or similar activities and utilities as the claimed compounds, or to induce, as a precursor, the same or similar activities and utilities as the claimed compounds. Exemplary derivatives of a parent compound include alkyls, hydroxyalkyls, carboxylic acids, salts, esters, and derivatives thereof.

[0115] Throughout the specification “alkyl” is generally used to refer to both unsubstituted alkyl groups and substituted alkyl groups; however, substituted alkyl groups are also specifically referred to herein by identifying the specific substituent(s) on the alkyl group. For example, the term “halogenated alkyl” or “haloalkyl” specifically refers to an alkyl group that is substituted with one or more halide, e.g., fluorine, chlorine, bromine, or iodine. Alternatively, the term “monohaloalkyl” specifically refers to an alkyl group that is substituted with a single halide, e.g. fluorine, chlorine, bromine, or iodine. The term “polyhaloalkyl” specifically refers to an alkyl group that is independently substituted with two or more halides, i.e. each halide substituent need not be the same halide as another halide substituent, nor do the multiple instances of a halide substituent need to be on the same carbon. The term “alkoxyalkyl” specifically refers to an alkyl group that is substituted with one or more alkoxy groups, asdescribed below. The term “aminoalkyl” specifically refers to an alkyl group that is substituted with one or more amino groups. The term “hydroxyalkyl” specifically refers to an alkyl group that is substituted with one or more hydroxy groups. When “alkyl” is used in one instance and a specific term such as “hydroxyalkyl” is used in another, it is not meant to imply that the term “alkyl” does not also refer to specific terms such as “hydroxyalkyl” and the like.

[0116] The term “ester” as used herein is represented by the formula — OC(O)A1or — C(O)OA1, where A1can be alkyl, cycloalkyl, alkenyl, cycloalkenyl, alkynyl, cycloalkynyl, aryl, or heteroaryl group as described herein.

[0117] The term “carboxylic acid” as used herein is represented by the formula — C(O)OH.B. ABBREVIATIONS

[0118] BCA banana-chitosan aerogel

[0119] BSCA banana-silk-chitosan aerogel

[0120] EDS energy-dispersive X-ray spectroscopy

[0121] FESM field emission scanning electron microscopy

[0122] FT-IR Fourier transform infrared spectroscopy

[0123] MB methylene blue

[0124] NaBC sodium bicarbonate

[0125] NC nanocellulose

[0126] NCC nanocrystalline cellulose

[0127] NFC nanofibrillated cellulose

[0128] PCM phase-changing materials

[0129] Ref intrinsic thermal resistance

[0130] SEM scanning electron microscopeC. DISCUSSION

[0131] The present disclosure provides for aerogels and hydrogels, such as cellulosic aerogels and cellulosic hydrogels, and methods of making and of use of the aerogels and hydrogels. The hydrogel and aerogel production methods can be characterized as relatively energy-efficient, cost-effective, and / or environmentally sustainable, making them economically feasible for scale-up. For example, the aerogels can be made without the use of liquid nitrogen, reducing the energy consumption for production. A variety of materials can be used to produce the hydrogels and aerogels, such as biobased, compostable, and industrial waste process materials, which can promote waste-to-product cost remediation for hydrogel and aerogel production. Depending on the materials used to produce the aerogels, the aerogels can be characterized as homogenous, heterogeneous, mesoporous, filled with functionalized materials, hybrid (blends and composites), or a combination thereof. The aerogels can be shaped or molded into a desired form for use, applied as a surface coating or a functional coating to textiles, used as a central layer in a multilayer structure for textiles,and / or related applications. For example, the aerogels can be used as functional coatings in the textile industry for thermal regulation.

[0132] The methods of making gels disclosed herein can be used to produce aerogels using a variety of source materials. Examples of aerogels that can be produced using the methods disclosed herein include: mesoporous aerogels comprising nanocellulose; mesoporous aerogels comprising nanocellulose and phase-changing materials; mesoporous hybrid aerogels comprising nanocellulose, phase-changing materials, and silica; hydrophobized / surface-modified aerogels comprising nanocellulose; aerogels comprising a silk-cellulose blend; aerogels comprising photocatalytic nanoparticles; and aerogels produced using various lignocellulosic and other bio-sources, such as hemp, cotton noil, sawdust, banana stalk fibers, algae, silk, and other fibrous sources.D. GEL COMPOSITION

[0133] This disclosure provides for gel compositions, such as aerogels, comprising a biopolymer, a biopolymer material, or a combination thereof; and an additional agent selected from a plasticizer, a crosslinking agent, or a combination thereof. The plasticizer can include an anionic cellulose derivative (e.g., carboxymethyl cellulose (CMC)), a nonionic cellulose derivative (e.g., methyl cellulose (MC), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, hydroxypropylmethyl cellulose (HPMC)), glycerol, sorbitol, xylitol, polyethylene glycol, a natural oil, lactic acid, a derivative of starch, triethyl citrate, diethyl phthalate, propylene glycol, or a combination thereof. The crosslinking agent can include chitosan, phytic acid, citric acid, tannic acid, calcium chloride, glutaraldehyde, transglutaminase, sodium alginate, lignin, a polyphenol, genipin, and a combination thereof.

[0134] The gel compositions disclosed herein can have an intrinsic thermal resistance (Ref) of about 0.001 °C m2 / Wto about 0.02 °C m2 / Wor greater than about 2 °C m2 / W. In one aspect, the compositions can have a porosity of greater than about 85%, greater than about 90%, or from about 80% to about 99%, about 85% to about 95%, about 85% to about 90%, or about 90% to about 95%. In another aspect, the compositions can have a specific surface are of at least 200 m2 / g or from about 200 m2 / g to about 1500 m2 / g, about 200 m2 / g to about 1000 m2 / g, about 200 m2 / g to about 500 m2 / g, about 500 m2 / g to about 1500 m2 / g, or about 1000 m2 / g to about 1500 m2 / g. In another aspect, the compositions can have an apparent density of about 0.003 g / cm3to about 0.5 g / cm3, about 0.003 g / cm3to about 0.3 g / cm3, about 0.003 g / cm3to about 0.1 g / cm3, about 0.01 g / cm3to about 0.5 g / cm3, or about 0.1 g / cm3to about 0.5 g / cm3. In one aspect, the composition can exhibit a good water absorption capacity (such as a composition comprising glycerol). For example, the compositions can have a water absorption capacity of about 30 g / g to about 65 g / g, about 30 g / g to about 50 g / g, about 40 g / g to about 65 g / g, or about 50 g / g to about 65 g / g, wherein g / g represents grams of water absorbed per gram of the composition.

[0135] In one aspect, the composition can be about 0.1% to about 20%, about 0.1% to about 15%, about 0.1 % to about 10%, about 0.1 % to about 5%, about 1 wt% to about 20 wt%, about 1 wt% to about 15 wt%, about 1 wt% to about 10 wt%, about 1 wt% to about 5 wt %, about 5 wt% to about 15 wt%, or about 10 wt% to about 15 wt% of plasticizer by weight. In another aspect, the aerogel can be about 12.5% of plasticizer by weight. In one aspect, the plasticizer can include CMC, glycerol, or a combination thereof. In another aspect, the composition can be from about 0.1% to about 10%, 0.1% to about 8%, 0.1% to about 6%, about 0.1% to about 4%, 0.1 % to about 2%, 1 % to about 10%, 1 % to about 8%, 1 % to about 6%, about 1 % to about 4%, or about 1% to about 2% of the crosslinking agent by weight. In one aspect, the crosslinking agent includes chitosan, phytic acid, or a combination thereof.

[0136] In one aspect, the composition can be from about 0.01% to about 99%, about 0.01% to about 60%, about 0.01 % to about 30%, 0.01% to about 10%, 0.1 % to about 90%, about 0.1% to about 80%, about 0.1% to about 70%, about 0.1% to about 50%, about 0.1% to about 60%, about 0.1% to about 40%, about 0.1% to about 30%, about 0.1 % to about 20%, about 0.1% to about 10%, about 5% to about 70%, about 10% to about 70%, about 30% to about 70%, about 20% to about 50%, or about 60% to about 80% of the biopolymer and / or the biopolymer material by weight. In one aspect, an aerogel that comprises less than about 50% of biopolymer and / or biopolymer material by weight can be used for thermal insulation, environmental remediation, and packaging due to their porous structure, low thermal conductivity, and durability. In another aspect, an aerogel that comprises more than about 60% biopolymer and / or biopolymer material by weight can be used in biomedical applications such as tissue engineering, biosensing, diagnostics, medical implants, drug delivery, and wound healing. Compositions of the present disclosure (e.g., aerogels) can also be used to deliver antibiotics, plant extracts, essential oils, and metallic nanoparticles due to their biocompatibility and non-toxicity. Additionally, they can also be suitable for energy storage applications due to their high surface area and porosity.

[0137] Biopolymers present in the compositions can include lignin, cellulose, hemicellulose, nanocellulose, silk fibroin, or any combination thereof. In one aspect, the weight percentage of lignin present in the composition can range from about 0.1 % to about 90% or about 0.1% to about 70%. Nanocellulose can include cellulose nanocrystals, cellulose nanofibrils, bacterial nanocellulose, or a combination thereof. Silk is a protein fiber predominantly produced by certain insect larvae, such as the Bombyx mori silkworm, for cocoon creation. Silk is composed mainly of the biopolymer fibroin. In one aspect, the aerogel can be about 10% to about 99%, about 10% to about 80%, or about 30% to about 70% of silk fibroin by weight. The composition can be from about 0.01% to about 99%, about 0.01% to about 60%, about 0.01% to about 30%, 0.01% to about 10%, 0.1% to about 90%, about 0.1% to about 80%, about 0.1% to about 70%, about 0.1% to about 50%, about 0.1% to about 60%, about 0.1 % to about 40%, about 0.1 % to about 30%, about 0.1 % to about 20%, about 0.1 % to about10%, about 5% to about 70%, about 10% to about 70%, about 30% to about 70%, about 20% to about 50%, or about 60% to about 80% of the biopolymer by weight.

[0138] Biopolymer material present in the aerogel can include algal biomass, wool fiber, lignocellulosic biomass, or a combination thereof. In one aspect, the aerogel can be about 0.01% to about 99%, about 0.01% to about 60%, about 0.01% to about 30%, 0.01 % to about 10%, 0.1 % to about 90%, about 0.1 % to about 80%, about 0.1% to about 70%, about 0.1% to about 50%, about 0.1% to about 60%, about 0.1% to about 40%, about 0.1% to about 30%, about 0.1% to about 20%, about 0.1% to about 10%, about 5% to about 70%, about 10% to about 70%, about 30% to about 70%, about 20% to about 50%, or about 60% to about 80% of biopolymer material by weight. The algal biomass can comprise a cyanobacteria, such as nostoc cyanobacteria. In one aspect, the composition can comprise from about 0.1 % to about 70%, about 0.1% to about 60%, about 0.1% to about 50%, about 0.1 % to about 40%, about 0.1 % to about 30%, about 0.1 % to about 20%, or about 0.1% to about 70% of algal biomass by weight. The lignocellulosic biomass can include banana biomass, such as banana biomass from a banana tree (e.g., the banana peduncle). In one aspect, the composition can comprise from about 0.1% to about 10%, about 0.1 % to about 8%, about 0.1 % to about 5%, or about 0.1 % to about 4% of the lignocellulosic biomass by weight. Wool fiber comprises the biopolymer keratin and can include other polymers, as well. In one aspect, the composition can comprise from about 0.1% to about 10%, about 0.1% to about 8%, about 0.1% to about 5%, or about 0.1% to about 4% wool fiber by weight. A composition comprising wool fiber can have a good thermal resistance, such as a thermal resistance of greater than about 2 °C m2 / W.

[0139] The aerogel can comprise additional materials, such as phase-changing materials (PCMs), silica, photocatalytic nanoparticles, flame retardants, or a combination thereof. PCMs can include materials such as eutectics, salt hydrates, organic materials, and high temperature salts. Examples of PCMs include sodium acetate and 1 ,2-benzisothiazol-3(2H)-one. In one aspect, an aerogel comprising nanocellulose can further comprise PCMs. PCMs can be present in the aerogel in a weight ratio of PCM to nanocellulose of about 1 :2 to about 4:5, about 1 :2 to about 7:10, or about 1 :2 to about 6:10. Flame retardants can include sodium bicarbonate, ammonium polyphosphate, melamine, zinc borate, hydrated magnesium hydroxide, aluminum trihydrate, a bio-based polyphosphate, a tannin, a silica aerogel, clay nanoparticles, borax, an intumescent composition, or a combination thereof. In one aspect, the composition can include from about 0.1% to about 20%, about 0.1% to about 15%, about 0.1 % to about 10%, or about 0.1% to about 5% flame retardant by weight. Note that other materials present in the composition can act as flame retardants (e.g., phytic acid) and characterization of them in one manner (e.g., phytic acid as a crosslinking agent) is not intended to imply that the component cannot act in other capacities (e.g., phytic acid could act as both a crosslinking agent and a flame retardant in the composition). The weight percentage of silica in the aerogel can range from about 1 % to about 10%, about 1 % to about 6%, or about1% to about 2%. The silica can be added in the form of fine solid powder, such as Enova® Aerogel IC3100. The silica powder can act as a compatible filled composite in the material.

[0140] The photocatalytic nanoparticles can include oxide nanoparticles. In one aspect, the composition can include a crosslinking agent and the photocatalytic nanoparticles can be present in the composition in a weight ratio of chitosan to photocatalytic nanoparticles of about 1 :4 to about 4: 1 , about 1 :4 to about 3: 1 , about 1 :4 to about 2: 1 , about 1 :4 to about 1 :1 , about 1 :2 to about 4:1 , about 1 :2 to about 3:1 , about 1 :2 to about 2:1 , or about 1 :2 to about 1 :1. In one aspect, the photocatalytic nanoparticles can have a variety of sizes and shapes. Nanoparticle shapes include, but are not limited to, spheres, cubes, rods, wires, polygonal plates, amorphous, polyhedrons, stars, shells, sheets, and the like. In another aspect, the nanoparticles can include oxide nanoparticles (e.g., titanium oxide nanoparticles), optionally doped with strontium, cerium, nitrogen, or a combination thereof. In one aspect, the nanoparticles can be synthesized using solvothermal methods including using an autoclave at different temperatures and times. The oxide nanoparticles can be further surface modified using NaOH or tetrabutylammonium hydroxide (TBAOH). The nanoparticles can be surface modified via hydrothermal methods, including using an autoclave at different temperatures and times with, for example, water as a solvent. In one aspect, the size of the nanoparticles ranges from about 10 nm to about 200 nm, about 10 nm to about 150 nm, about 10 nm to about 100 nm, about 50 nm to about 200 nm, about 50 nm to about 150 nm, about 50 nm to about 100 nm, or about 60 nm to about 90 nm.E. METHOD OF MAKING AND OF USING A GEL

[0141] Also disclosed herein is a method of making a gel, comprising mixing together at least a polymeric material (e.g., a bio-polymeric material) comprising at least one biopolymer, at least one biopolymer material, or a combination thereof; an additional agent selected from a plasticizer, a crosslinking agent, or a combination thereof; and a solvent (e.g., water, acetic acid) to form a slurry; homogenizing the slurry to form a hydrogel; aerating the hydrogel to form a foam; freezing the foam at a temperature of about -90 °C to about -10 °C; and freeze- drying the foam at a temperature of about -90 °C to about -20 °C and about 0.1 mbar to about 1 mbar pressure to form an aerogel. A plasticizer can be added to a material and can, in one aspect, make the material more flexible and softer. The plasticizer can include an anionic cellulose derivative (e.g., carboxymethyl cellulose (CMC)), a nonionic cellulose derivative (e.g., methyl cellulose (MC), hydroxyethyl cellulose (HEC), hydroxypropyl cellulose, hydroxypropylmethyl cellulose (HPMC)), glycerol, sorbitol, xylitol, polyethylene glycol, a natural oil, lactic acid, a derivative of starch, triethyl citrate, diethyl phthalate, propylene glycol, or a combination thereof, as discussed elsewhere herein. The crosslinking agent can include chitosan, phytic acid, citric acid, tannic acid, calcium chloride, glutaraldehyde, transglutaminase, sodium alginate, lignin, a polyphenol, genipin, and a combination thereof, as discussed elsewhere herein. Biopolymers can include lignin, cellulose, hemicellulose,nanocellulose, silk fibroin, and any combination thereof, as discussed elsewhere herein. Biopolymer material present in the aerogel can include algal biomass, wool fiber, lignocellulosic biomass, or a combination thereof, as discussed elsewhere herein.

[0142] In a further aspect, the foam can be frozen at a temperature ranging from about -90 °C to about -10 °C, about -80 °C to about -10 °C, about -70 °C to about -10 °C, about -60°C to about -10 °C, about -50 °C to about -10 °C, about -40 °C to about -10 °C, about -30°C to about -10 °C, about -90 °C to about -20 °C, about -80 °C to about -20 °C, about -70°C to about -20 °C, about -60 °C to about -20 °C, about -50 °C to about -20 °C, about -90°C to about -50 °C, about -90 °C to about -70 °C, about -50 °C to about -10 °C, or about -70 °C to about -30 °C. The foam can be frozen (e.g., held at the indicated temperature) for about 0.1 hours to about 30 hours, about 0.1 hours to about 25 hours, about 0.1 hours to about 20 hours, about 0.1 hours to about 15 hours, about 0.1 hours to about 12 hours, about 0.1 hours to about 10 hours, about 0.1 hours to about 8 hours, about 0.1 hours to about 6 hours, about 2 hours to about 12 hours, about 4 hours to about 12 hours, about 6 hours to about 12 hours, about 2 hours to about 10 hours, or about 4 hours to about 8 hours,

[0143] In another further aspect, the foam can be freeze-dried at a temperature ranging from about -90 °C to about -20 °C, about -80 °C to about -20 °C, about -70 °C to about -20 °C, about -60 °C to about -20 °C, about -50 °C to about -20 °C, about -90 °C to about -30 °C, about -90 °C to about -40 °C, about -80 °C to about -30 °C, about -80 °C to about -40 °C, about -90 °C to about -60 °C, or about -60 °C to about -20 °C. The foam can be freeze-dried(e.g., held at the indicated temperature) for about 1 hour to about 60 hours, about 1 hour to about 55 hours, about 1 hour to about 50 hours, about 1 hour to about 45 hours, about 1 hour to about 40 hours, about 1 hour to about 35 hours, about 1 hour to about 30 hours, about 1 hour to about 25 hours, about 1 hour to about 20 hours, about 1 hour to about 18 hours, about 1 hour to about 16 hours, about 1 hour to about 14 hours, about 1 hour to about 12 hours, about 2 hours to about 20 hours, about 4 hours to about 20 hours, about 6 hours to about 20 hours, about 8 hours to about 20 hours, about 10 hours to about 20 hours, about 12 hours to about 20 hours, about 4 hours to about 16 hours, about 4 hours to about 12 hours, about 4 hours to about 8 hours, or about 6 hours to about 16 hours. In another aspect, the foam can be freeze-dried until it is completely dried (e.g., there is little to no moisture remaining in the foam). This can be determined by a variety of methods, including visual or quantitative determinations. A quantitative determination can include, for example, weighing the foam and freeze-drying the foam until the weight of the foam remains constant. As an example, the weight of the foam can decrease as moisture leaves the foam through the freeze-drying process, with the weight eventually becoming relatively stable as little to no moisture is left.

[0144] Forming the slurry can involve a thermal treatment process. In one aspect, forming the slurry can further include mixing the materials (e.g., the polymeric material, the additional agent, and the solvent) at a temperature above room temperature, followed by allowing the slurry to cool prior to homogenizing. In one aspect, the materials are mixed at a temperatureranging from about 80 °C to about 170 °C, about 80 °C to about 150 °C, about 80 °C to about 130 °C, or about 80 °C to about 110 °C until the solid materials (e.g., plasticizer and polymeric material) are relatively evenly dispersed throughout the solution. In a further aspect, the slurry is then allowed to cool to a temperature ranging from about 60 °C to about 80 °C prior to homogenizing. In a further aspect, the slurry can be allowed to sit at the cooler temperature to age prior to homogenizing. In another aspect, the method further comprises allowing the hydrogel to cool to a temperature of about 2 °C to about 20 °C prior to aerating the hydrogel, for example for a period of about 1 hour to about 20 hours, about 2 hours to about 20 hours, about 1 hour to about 15 hours, about 2 hours to about 15 hours, about 1 hour to about 10 hours, or about 2 hours to about 10 hours. In one aspect, the thermal treatment process can be used when the slurry includes cellulose. Treating a slurry containing cellulose in this manner can break down cellulose components from a macro form to a nano form (e.g., defibrillating cellulose fibril bundles). Using a thermal pretreatment process as part of the slurry formation can reduce the operating temperature required for the homogenization step (e.g., homogenization can be carried out at a temperature of less than 90 °C, such as about 70 °C to 90°C). Traditionally, a higher temperature was necessary for the gelling step in order to defibrillate cellulose in a slurry. Additionally, the thermal pretreatment process can reduce the number of passes through a homogenizer needed to form a hydrogel in the homogenizing step.

[0145] As a general example, the slurry can be formed by combining at least a plasticizer, the polymeric material, and water (e.g., deionized water) at a temperature above room temperature (e.g., about 100 °C) and blending the slurry (e.g., mixing at 200 rpm) until the solid materials (the plasticizer and the polymeric material) are relatively evenly dispersed throughout the solution (e.g., blending for 15 minutes). The slurry can then be homogenized (i.e., introduced to or passed through a homogenizer) and allowed to reach a gelling point. In one aspect, homogenizing the slurry is done at a temperature above room temperature and at a pressure above atmospheric pressure until the slurry reaches its gelling point, forming a hydrogel material. In a further aspect, during the homogenization process, the slurry can be kept at a temperature ranging from about 70 °C to about 100 °C, about 70 °C to about 90 °C, or about 75 °C to about 85 °C. The temperature can be varied during the homogenization process as needed. In another aspect, during the homogenization process, the slurry can be kept at a pressure ranging from about 500 bar to about 800 bar, about 550 bar to about 750 bar, or about 600 bar to about 700 bar. The pressure can be varied during the homogenization process as needed. The pressure can be selected based on the pressure needed for the slurry to reach its gel point. For example, the pressure during an initial phase of the homogenization process can be kept at a lower pressure (e.g., 500 bar) relative to the pressure during a later phase of the homogenization process (e.g., 650 bar). Examples of methods used for producing a hydrogel using a variety of starting materials can be found in the Examples.

[0146] Following homogenization to form a hydrogel, the hydrogel can be formed into a foam. When creating a stable foam from a hydrogel, various aeration methods such as mechanical, physical, and chemical foaming can be employed. For example, mechanical foaming can comprise a vigorous high-speed stirring of the hydrogel at about 10,000 rpm or higher.

[0147] In one aspect, the slurry can include a plasticizer and polymeric material combined in a weight ratio of about 1:20 to about 1 :100 (plasticizer: polymeric material). In another aspect, the slurry can include a plasticizer and polymeric material combined in a ratio of about 1 :40.

[0148] The polymeric materials can include a biopolymer material such as a lignocellulosic biomass. Lignocellulosic biomass such as cotton noil, hemp, sawdust, banana (e.g., banana stalk), or a combination thereof can be used. In one aspect, the lignocellulosic biomass can include from about 10 wt% to about 99 wt% cellulose and from about 1 wt% to about 50 wt% lignin. In another aspect, the polymeric materials can include biopolymers derived from biopolymer materials such as cellulose derived from lignocellulosic biomass. In one aspect, the polymeric material can include biopolymers such as cellulose, nanocellulose, silk fibroin, or any combination thereof. In one aspect, the polymeric material comprises both a silk fibroin and cellulose and / or nanocellulose in a weight ratio of silk fibroin material cellulose / nanocellulose of about 3:10 to about 7:10 (silk fibroimcellulose and / or nanocellulose). In another aspect, the polymeric material comprises a silk fibroin and no cellulose or nanocellulose. In another aspect, the polymeric material can include biopolymers such as lignin in addition to other biopolymers and / or biopolymer materials. The polymeric material can comprise lignin in a weight ratio of lignin to remaining polymeric material of about 1 :10 to about 1 :1.

[0149] The methods disclosed herein for producing an aerogel can also include adding additional materials by incorporating them into the gel or gel-precursor materials prior to the aeration step, such as by mixing the materials with the hydrogel prior to aerating or mixing the materials into the slurry. Additionally, the additional materials can be incorporated into the foam prior to freezing, such as during the aeration step. The additional materials can include PCMs, silica, photocatalytic nanoparticles, biopolymeric material (e.g., algal biomass), flame retardants, or a combination thereof, a discussed elsewhere herein. In one aspect, a gel produced using a cellulosic material (cellulose and / or nanocellulose) can further comprise PCMs. PCMs can be added to the hydrogel prior to aeration in a weight ratio of PCM to cellulosic material present in the hydrogel of about 1 :2 to about 4:5. Examples of PCMs include sodium acetate and 1 ,2-benzisothiazol-3(2H)-one.

[0150] In one aspect, a gel produced using a cellulosic material can further comprise silica. The silica can be added in the form of fine solid powder, such as Enova® Aerogel IC3100. The weight ratio of silica to cellulosic material can range from about 1 :40 to about 1 :8 (silica: cellulosic material). The silica can be added to the hydrogel prior to aeration.

[0151] Algal biomass can be incorporated into the gel by adding it to the hydrogel prior to aeration at a weight ratio of about 1 :4 to about 3:1 (hydrogekalgal biomass). Beforeincorporating into the hydrogel, algal biomass can be rinsed with water. In one aspect, the hydrogel the algal biomass is added to can comprise silk fibroin biopolymer.

[0152] The photocatalytic nanoparticles or nano photocatalysts can be incorporated into the gel prior to the aeration step or be incorporated during the aeration step. For example, the method can further comprise incorporating the photocatalytic nanoparticles into the hydrogel or into the foam. In one aspect, the nanoparticles can be mixed (e.g., at about 500 rpm) with the hydrogel for about 1 hour to about 7 days, about 1 hour to about 6 days, about 1 hour to about 5 days, about 1 hour to about 4 days, about 1 hour to about 3 days, about 1 day to about 7 days, about 1 day to about 6 days, about 1 day to about 5 days, or about 1 day to about 4 days. The nanoparticles can be mixed with the hydrogel at room temperature.

[0153] The photocatalytic nanoparticles or nano photocatalysts can include oxide nanoparticles (e.g., titanium oxide nanoparticles) as discussed in further detail elsewhere herein.

[0154] Following aeration, the aerated foam can be molded into a desired shape for use. Aerated foam can be placed in a container, such as a container comprising aluminum, glass, or a plastic, and then undergo freezing and freeze-drying steps to form the aerogel. For making surface coatings, functional coatings, and / or multilayer structures from aerogels, the aerated foam can be coated onto a surface, prior to the freezing and freeze-drying steps. The coating can be done, for example, by using a leveling coating applicator. For example, aerated foam can be applied to a surface of a textile (e.g., cotton), a paper, or a polymer film (e.g., polypropylene film or polylactic acid film). The foam can form a layer on the surface of about 1 mm to about 5 mm thick. Another layer of a textile can be placed on top of the foam layer in order to form multilayer compact units. After forming the aerated foam layer and, optionally, adding an additional layer onto the foam, the units can undergo the freezing and freeze-drying process to form a structure comprising an aerogel. A multilayer structure can have different configurations, such as [textile, film, or paper]-aerogel-[textile, film, or paper], where any combination of the layers can be used (e.g., paper-aerogel-textile). In one aspect, the thickness of the units can range from about 0.2 mm to about 5 mm, with aerogels as a central layer for multilayer structures. In one aspect, the units comprising the aerogels can have an intrinsic thermal resistance (Ref) of about 0.001 °Cm2 / W to about 0.02 °Cm2 / W.

[0155] The methods of making the compositions (e.g., hydrogels and aerogels) disclosed herein do not use liquid nitrogen in the freeze-drying process, as is traditionally done, instead replacing its use with an efficient process of mixing, freezing, and deep-freezing. Employing liquid nitrogen in standard freeze-drying processes can lead to significant handling and operational challenges due to its extremely low boiling point of -196 °C, which causes it to vaporize into a gas at room temperature. Direct contact with liquid nitrogen can result in burns and frostbite to the person handling it, while accidental inhalation or ingestion poses a risk of asphyxiation. In addition, the expense of liquid nitrogen makes it a costly option for producing aerogels on a large scale. Additionally, in the method of making a gel disclosed herein, thesteps of processing the hydrogel to form the aerogel does not require the use of organic solvents. Both of these factors contribute to an overall method of making that is more cost- effective and environmentally sustainable than traditional methods of producing hydrogel and aerogels.

[0156] Aerogels can be derived from various materials such as hydrogels, xerogels, cryogels, and similar gel substances. Traditionally, aerogels are created by supercritical drying of gels derived from the sol-gel procedure. During a traditional aerogel production process using solgel methods, it’s crucial to maintain the shape and porosity of the gel, especially as the solvent evaporates from the gel's internal and external surfaces. Supercritical drying of the gel involves multiple steps, such as cosolvent solubilization, immersing and pressurizing the sample with a supercritical solvent, and gradual depressurization to eliminate water, cosolvent, and solvent. Being able to eliminate some or all of these steps from the aerogel production process can reduce the cost of the process and further enable its implementation on larger scales (e.g., industrial scales).

[0157] While embodiments of the present disclosure are described in connection with the Examples and the corresponding text and figures, there is no intent to limit the disclosure to the embodiments in these descriptions. On the contrary, the intent is to cover all alternatives, modifications, and equivalents included within the spirit and scope of embodiments of the present disclosure.F. ASPECTS

[0158] Aspect 1. A method for producing an aerogel, comprising: mixing together a polymeric material, a solvent, and an additional agent to form a slurry, wherein the additional agent is selected from a plasticizer, a crosslinking agent, or a combination thereof; homogenizing the slurry to form a hydrogel; aerating the hydrogel to form a foam; freezing the foam at a temperature of about -90 °C to about -10 °C; and freeze-drying the foam at a pressure of about 0.1 mbar to about 1 mbar and a temperature of about -90 °C to about -20 °C to form an aerogel; wherein the polymeric material comprises at least one biopolymer, at least one biopolymer material, or a combination thereof.

[0159] Aspect 2. The method of aspect 1 , wherein the foam is frozen for about 0.1 hours to about 30 hours.

[0160] Aspect 3. The method of aspect 1 , wherein the foam is frozen for about 1 hours to about 60 hours.

[0161] Aspect 4. The method of any one of aspects 1-3, wherein the foam is frozen at a temperature of about -30 °C to about -10 °C.

[0162] Aspect 5. The method of any one of aspects 1-3, wherein the foam is frozen at a temperature of about -90 °C to about -70 °C.

[0163] Aspect 6. The method of any one of aspects 1-5, wherein the foam is freeze-dried for about 1 hour to about 20 hours.

[0164] Aspect 7. The method of any one of aspects 1-6, wherein the foam is freeze-dried at a temperature of about -50 °C to about -20 °C.

[0165] Aspect 8. The method of any one of aspects 1-6, wherein the foam is freeze-dried at a temperature of about -90 °C to about -60 °C.

[0166] Aspect 9. The method of any one of aspects 1-8, wherein forming the slurry further comprises: mixing together the polymeric material, the solvent, and the additional agent at a temperature of about 80 °C to about 110 °C; and allowing the slurry to cool prior to homogenizing.

[0167] Aspect 10. The method of aspect 9, wherein the slurry is allowed to cool to a temperature of about 60 °C to about 80 °C prior to homogenizing.

[0168] Aspect 11. The method of any one of aspects 1-10, wherein the method further comprises allowing the hydrogel to cool to a temperature of about 2 °C to about 20 °C prior to aerating the hydrogel.

[0169] Aspect 12. The method of aspect 11, wherein the hydrogel is allowed to cool for about 2 hours to about 20 hours.

[0170] Aspect 13. The method of any one of aspects 1-12 wherein the foam is placed into a container prior to freezing or prior to freeze-drying.

[0171] Aspect 14. The method of any one of aspects 1-12, wherein the foam is coated onto a surface to form a foam layer prior to freezing or prior to freeze-drying, wherein the surface comprises a textile, a paper, or a polymer film.

[0172] Aspect 15. The method of aspect 14, wherein an additional layer comprising a textile, a paper, or a polymer film is placed onto the foam layer prior to freezing and freeze-drying.

[0173] Aspect 16. The method of aspect 14 or aspect 15, wherein the foam layer has a thickness of from about 1 mm to about 5 mm.

[0174] Aspect 17. The method of any one of aspects 1-16, wherein the slurry comprises the plasticizer in a weight ratio of plasticizer to polymeric material of about 1 :20 to about 1 :10.

[0175] Aspect 18. The method of aspect 17, wherein the plasticizer comprises an anionic cellulose derivative, a nonionic cellulose derivative, glycerol, sorbitol, xylitol, polyethylene glycol, a natural oil, lactic acid, a derivative of starch, triethyl citrate, diethyl phthalate, propylene glycol, or a combination thereof.

[0176] Aspect 19. The method of aspect 17, wherein the plasticizer comprises carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, glycerol, sorbitol, xylitol, polyethylene glycol, a natural oil, lactic acid, a derivative of starch, triethyl citrate, diethyl phthalate, propylene glycol, or a combination thereof.

[0177] Aspect 20. The method of aspect 17, wherein the plasticizer comprises carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropylmethyl cellulose, glycerol, and any combination thereof.

[0178] Aspect 21. The method of any one of aspects 1-20, wherein the slurry comprises the crosslinking agent in a weight ratio of the crosslinking agent to the polymeric material of about 1 :10 to about 1 :1.

[0179] Aspect 22. The method of aspect 21 , wherein the crosslinking agent comprises chitosan, phytic acid, citric acid, tannic acid, calcium chloride, glutaraldehyde, transglutaminase, sodium alginate, lignin, a polyphenol, genipin, or a combination thereof.

[0180] Aspect 23. The method of any one of aspects 1-22, wherein the at least one biopolymer comprises lignin, cellulose, hemicellulose, nanocellulose, silk fibroin, or any combination thereof.

[0181] Aspect 24. The method of any one of aspects 1-23, wherein the at least one biopolymer material comprises algal biomass, wool fiber, lignocellulosic biomass, or a combination thereof.

[0182] Aspect 25. The method of any one of aspects 1-24, wherein at least one additional material selected from a phase-changing material, silica, photocatalytic nanoparticles, a second biopolymer material, a flame retardant, and any combination thereof, is incorporated into the slurry, incorporated into the hydrogel prior to aerating, or incorporated into the foam prior to freezing.

[0183] Aspect 26. The method of any one of aspects 1-25, wherein the slurry comprises the at least one biopolymer and the plasticizer; wherein the at least one biopolymer comprises cellulose and the plasticizer comprises the anionic cellulose derivative, the nonionic cellulose derivative, or a combination thereof.

[0184] Aspect 27. The method of aspect 26, further comprising incorporating a phasechanging material into the foam prior to freezing.

[0185] Aspect 28. The method of aspect 27, wherein the phase-changing material is selected from the group consisting of eutectics, salt hydrates, organic materials, and high-temperature salts.

[0186] Aspect 29. The method of aspect 27, wherein the phase-changing material is selected from the group consisting of sodium acetate, 1 ,2-benzisothiazol-3(2H)-one, and a combination thereof.

[0187] Aspect 30. The method of any one of aspects 26-29, wherein the method further comprises incorporating silica into the foam prior to freezing.

[0188] Aspect 31. The method of any one of aspects 1-26, wherein the method further comprises mixing algal biomass with the hydrogel prior to aerating.

[0189] Aspect 32. The method of aspect 31 , wherein the algal biomass is mixed with the hydrogel prior to aerating at a weight ratio of hydrogel to algal biomass of about 1 :4 to about 3:1.

[0190] Aspect 33. The method of aspect 31 or aspect 32, wherein the algal biomass is a cyanobacteria.

[0191] Aspect 34. The method of aspect 31 or aspect 32, wherein the algal biomass is a nostoc cyanobacteria.

[0192] Aspect 35. The method of any one of aspects 31-34, wherein the slurry further comprises the at least one biopolymer comprising silk fibroin.

[0193] Aspect 36. The method of any one of aspects 1-25, wherein the slurry comprises the at least one biopolymer and the crosslinking agent; wherein the at least one biopolymer comprises cellulose and the crosslinking agent comprises chitosan.

[0194] Aspect 37. The method of aspect 36, wherein the slurry further comprises the at least one biopolymer material comprising wool fiber.

[0195] Aspect 38. The method of aspect 36, wherein the slurry further comprises the plasticizer further comprising glycerol.

[0196] Aspect 39. The method of any one of aspects 1-36, wherein the method further comprises mixing the hydrogel with photocatalytic nanoparticles prior to aerating.

[0197] Aspect 40. The method of any one of aspects 1-36 or aspect 39, wherein the photocatalytic nanoparticles are mixed with the hydrogel in a nanoparticle to additional agent weight ratio of about 1 :4 to about 4: 1.

[0198] Aspect 41. The method of aspect 39 or aspect 40, wherein the photocatalytic nanoparticles are mixed with the hydrogel for about 1 hour to about 7 days.

[0199] Aspect 42. The method of any one of aspects 39-41, wherein the photocatalytic nanoparticles are titanium oxide nanoparticles.

[0200] Aspect 43. The method of any one of aspects 1-25, wherein the slurry comprises the at least one biopolymer material and the crosslinking agent; wherein the at least one biopolymer material comprises lignocellulosic biomass and the crosslinking agent comprises chitosan.

[0201] Aspect 44. The method of aspect 43, wherein the lignocellulosic biomass comprises banana biomass.

[0202] Aspect 45. The method of aspect 43 or aspect 44, wherein the slurry further comprises the at least one biopolymer comprising silk fibroin.

[0203] Aspect 46. The method of any one of aspects 43-45, wherein the crosslinking agent further comprises phytic acid.

[0204] Aspect 47. The method of any one of aspects 43-45, wherein the method further comprises incorporating phytic acid into the hydrogel prior to aerating.

[0205] Aspect 48. The method of any one of aspects 43-45, wherein the method further comprises incorporating photocatalytic nanoparticles into the foam prior to freezing.

[0206] Aspect 49. The method of aspect 48, wherein the photocatalytic nanoparticles are oxide nanoparticles.

[0207] Aspect 50. The method of aspect 49, wherein the oxide nanoparticles are titanium oxide nanoparticles.

[0208] Aspect 51. The method of any one of aspects 36-45, wherein the method further comprises incorporating a flame retardant into the slurry or into the hydrogel prior to aerating.

[0209] Aspect 52. The method of aspect 51 , wherein the flame retardant is selected from sodium bicarbonate, ammonium polyphosphate, melamine, zinc borate, hydrated magnesium hydroxide, aluminum trihydrate, a bio-based polyphosphate, a tannin, a silica aerogel, clay nanoparticles, borax, an intumescent composition, or a combination thereof.

[0210] Aspect 53. The method of any one of aspects 1-52, wherein the aerogel has a porosity of greater than about 85%.

[0211] Aspect 54. The method of any one of aspects 1-52, wherein the aerogel has a porosity of from about 85% to about 95%.

[0212] Aspect 55. The method of any one of aspects 1-54, wherein the aerogel has a specific surface area of at least 200 m2 / g.

[0213] Aspect 56. The method of any one of aspects 1-54, wherein the aerogel has a specific surface area of about 200 m2 / g to about 1500 m2 / g.

[0214] Aspect 57. The method of any one of aspects 1-56, wherein the aerogel has an apparent density of about 0.003 g / cm3to about 0.5 g / cm3.

[0215] Aspect 58. The method of any one of aspects 1 -57, wherein the aerogel has an intrinsic thermal resistance of about 0.001 °Cm2 / W to about 0.02 °Cm2 / W.

[0216] Aspect 59. The method of any one of aspects 1-58, wherein the aerogel comprises nanocellulose material comprising cellulose nanofibrils, cellulose nanocrystals, or a combination thereof.

[0217] Aspect 60. A method for producing an aerogel, comprising: mixing together a polymeric material, solvent, and an additional agent to form a slurry, wherein the additional agent is selected from a plasticizer, chitosan, or a combination thereof; homogenizing the slurry to form a hydrogel; aerating the hydrogel to form a foam; freezing the foam at a temperature of about -90 °C to about -10 °C; and freeze-drying the foam at a pressure of about 0.1 mbar to about 1 mbar and a temperature of about -90 °C to about -20 °C to form an aerogel; wherein the polymeric material comprises at least one biopolymer, at least one biopolymer material, or a combination thereof.

[0218] Aspect 61. The method of aspect 60, wherein the foam is frozen for about 0.1 hours to about 12 hours.

[0219] Aspect 62. The method of aspect 60, wherein the foam is frozen for 5 hours to about 12 hours.

[0220] Aspect 63. The method of any one of aspects 60-62, wherein the foam is frozen at a temperature of about -30 °C to about -10 °C.

[0221] Aspect 64. The method of any one of aspects 60-62, wherein the foam is frozen at a temperature of about -90 °C to about -70 °C.

[0222] Aspect 65. The method of any one of aspects 60-64, wherein the foam is freeze-dried for about 1 hour to about 20 hours.

[0223] Aspect 66. The method of any one of aspects 60-65, wherein the foam is freeze-dried at a temperature of about -50 °C to about -20 °C.

[0224] Aspect 67. The method of any one of aspects 60-65, wherein the foam is freeze-dried at a temperature of about -90 °C to about -60 °C.

[0225] Aspect 68. The method of any one of aspects 60-67, wherein forming the slurry further comprises: mixing together the polymeric material, the solvent, and the additional agent at a temperature of about 80 °C to about 110 °C; and allowing the slurry to cool prior to homogenizing.

[0226] Aspect 69. The method of aspect 68, wherein the slurry is allowed to cool to a temperature of about 60 °C to about 80 °C prior to homogenizing.

[0227] Aspect 70. The method of any one of aspects 60-69, wherein the foam is placed into a container prior to freezing or prior to freeze-drying.

[0228] Aspect 71. The method of any one of aspects 60-69, wherein the foam is coated onto a surface to form a foam layer prior to freezing and freeze-drying, wherein the surface comprises a textile, a paper, or a polymer film.

[0229] Aspect 72. The method of aspect 71 , wherein an additional layer comprising a textile, a paper, or a polymer film is placed onto the foam layer prior to freezing and freeze-drying.

[0230] Aspect 73. The method of aspect 71 or aspect 72, wherein the foam layer has a thickness of from about 1 mm to about 5 mm.

[0231] Aspect 74. The method of any one of aspects 60-73, wherein the slurry comprises the plasticizer in a weight ratio of plasticizer to polymeric material of about 1 :20 to about 1:10.

[0232] Aspect 75. The method of any aspect 74, wherein the plasticizer comprises an anionic cellulose derivative, a noniononic cellulose derivative, or a combination thereof.

[0233] Aspect 76. The method of aspect 74, wherein the plasticizer comprises carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropylmethyl cellulose, and any combination thereof.

[0234] Aspect 77. The method of any one of aspects 60-76, wherein the slurry comprises chitosan in a weight ratio of chitosan to the polymeric material of about 1:10 to about 1 :1.

[0235] Aspect 78. The method of any one of aspects 60-77, wherein the at least one biopolymer comprises lignin, cellulose, hemicellulose, nanocellulose, silk fibroin, or any combination thereof.

[0236] Aspect 79. The method of any one of aspects 60-77, wherein the at least one biopolymer comprises cellulose, nanocellulose, or a combination thereof.

[0237] Aspect 80. The method of any one of aspects 60-79, wherein the at least one biopolymer material comprises algal biomass, lignocellulosic biomass, or a combination thereof.

[0238] Aspect 81. The method of aspect 80, wherein the lignocellulosic biomass comprises from about 10 wt% to about 99 wt% cellulose and from about 1 wt% to about 50 wt% lignin.

[0239] Aspect 82. The method of any one of aspects 60-81 , wherein at least one additional material selected from a phase-changing material, silica, photocatalytic nanoparticles, a second biopolymer material, and any combination thereof, is incorporated into the slurry, incorporated into the hydrogel prior to aerating, or incorporated into the foam prior to freezing.

[0240] Aspect 83. The method of any one of aspects 60-82, wherein the slurry comprises the at least one biopolymer and the plasticizer; wherein the at least one biopolymer comprises cellulose and the plasticizer comprises the anionic cellulose derivative, the nonionic cellulose derivative, or a combination thereof.

[0241] Aspect 84. The method of aspect 83, further comprising incorporating a phasechanging material into the foam prior to freezing.

[0242] Aspect 85. The method of aspect 84, wherein the phase-changing material is selected from the group consisting of eutectics, salt hydrates, organic materials, and high-temperature salts.

[0243] Aspect 86. The method of aspect 84, wherein the phase-changing material is selected from the group consisting of sodium acetate, 1 ,2-benzisothiazol-3(2H)-one, and a combination thereof.

[0244] Aspect 87. The method of any one of aspects 83-86, wherein the method further comprises incorporating silica into the foam prior to freezing.

[0245] Aspect 88. The method of any one of aspects 60-83, wherein the method further comprises mixing algal biomass with the hydrogel prior to aerating.

[0246] Aspect 89. The method of aspect 88, wherein the algal biomass is mixed with the hydrogel prior to aerating at a weight ratio of hydrogel to algal biomass of about 1 :4 to about 3:1.

[0247] Aspect 90. The method of aspect 88 or aspect 89, wherein the algal biomass is a cyanobacteria.

[0248] Aspect 91. The method of aspect 88 or aspect 89, wherein the algal biomass is a nostoc cyanobacteria.

[0249] Aspect 92. The method of any one of aspects 60-91 , wherein the slurry further comprises the at least one biopolymer comprising silk fibroin.

[0250] Aspect 93. The method of any one of aspects 60-82, wherein the slurry comprises the at least one biopolymer material and chitosan; wherein the at least one biopolymer material comprises lignocellulosic biomass.

[0251] Aspect 94. The method of aspect 93, wherein the lignocellulosic biomass comprises banana biomass.

[0252] Aspect 95. The method of aspect 93 or aspect 94, wherein the slurry further comprises the at least one biopolymer comprising silk fibroin.

[0253] Aspect 96. The method of any one of aspects 93-95, wherein the method further comprises incorporating photocatalytic nanoparticles into the foam prior to freezing.

[0254] Aspect 97. The method of aspect 96, wherein the photocatalytic nanoparticles are oxide nanoparticles.

[0255] Aspect 98. The method of aspect 97, wherein the oxide nanoparticles are titanium oxide nanoparticles.

[0256] Aspect 99. The method of any one of aspects 60-98, wherein the aerogel has a porosity of greater than about 85%.

[0257] Aspect 100. The method of any one of aspects 60-98, wherein the aerogel has a porosity of from about 85% to about 95%.

[0258] Aspect 101. The method of any one of aspects 60-100, wherein the aerogel has a specific surface area of at least 200 m2 / g.

[0259] Aspect 102. The method of any one of aspects 60-100, wherein the aerogel has a specific surface area of about 200 m2 / g to about 1500 m2 / g.

[0260] Aspect 103. The method of any one of aspects 60-102, wherein the aerogel has an apparent density of about 0.003 g / cm3to about 0.5 g / cm3.

[0261] Aspect 104. The method of any one of aspects 60-103, wherein the aerogel has an intrinsic thermal resistance of about 0.001 °C m2 / W to about 0.02 °C m2 / W.

[0262] Aspect 105. The method of any one of aspects 60-104, wherein the aerogel comprises nanocellulose material comprising cellulose nanofibrils, cellulose nanocrystals, or a combination thereof.

[0263] Aspect 106. A composition, comprising: a biopolymer, a biopolymer material, or a combination thereof; and an additional agent selected from a plasticizer, a crosslinking agent, or a combination thereof; wherein the plasticizer comprises an anionic cellulose derivative, a nonionic cellulose derivative, glycerol, sorbitol, xylitol, polyethylene glycol, a natural oil, lactic acid, a derivative of starch, triethyl citrate, diethyl phthalate, propylene glycol, or a combination thereof; and wherein the crosslinking agent comprises chitosan, phytic acid, citric acid, tannic acid, calcium chloride, glutaraldehyde, transglutaminase, sodium alginate, lignin, a polyphenol, genipin, or a combination thereof.

[0264] Aspect 107. The composition of aspect 106, wherein the plasticizer comprises carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, glycerol, sorbitol, xylitol, polyethylene glycol, a natural oil, lactic acid, a derivative of starch, triethyl citrate, diethyl phthalate, propylene glycol, or a combination thereof.

[0265] Aspect 108. The composition of aspect 106, wherein the plasticizer comprises carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, glycerol, and any combination thereof.

[0266] Aspect 109. The composition of any one of aspects 106-108, wherein the composition is from about 0.1 % to about 20% plasticizer by weight.

[0267] Aspect 110. The composition of any one of aspects 106-108, wherein the composition is from about 0.1% to about 15% plasticizer by weight.

[0268] Aspect 111. The composition of any one of aspects 106-110, wherein the composition is from about 0.1% to about 10% crosslinking agent by weight.

[0269] Aspect 112. The composition of any one of aspects 106-110, wherein the composition is from about 0.1% to about 5% crosslinking agent by weight.

[0270] Aspect 113. The composition of any one of aspects 106-112, wherein the biopolymer comprises lignin, cellulose, hemicellulose, nanocellulose, silk fibroin, or any combination thereof.

[0271] Aspect 114. The composition of any one of aspects 106-113, wherein the composition is from about 0.01% to about 99% of the biopolymer by weight.

[0272] Aspect 115. The composition of any one of aspects 106-113, wherein the composition is from about 20% to about 50% of the biopolymer by weight.

[0273] Aspect 116. The composition of any one of aspects 106-113, wherein the composition is from about 60% to about 80% of the biopolymer by weight.

[0274] Aspect 117. The composition of any one of aspects 106-116, wherein the biopolymer material comprises algal biomass, wool fiber, lignocellulosic biomass, or a combination thereof.

[0275] Aspect 118. The composition of any one of aspects 106-117, wherein the composition is from about 0.1% to about 90% of the biopolymer material by weight.

[0276] Aspect 119. The composition of any one of aspects 106-117, wherein the composition is from about 0.1% to about 70% of the biopolymer material by weight.

[0277] Aspect 120. The composition of any one of aspects 106-117, wherein the composition is from about 0.1% to about 50% of the biopolymer material by weight.

[0278] Aspect 121. The composition of any one of aspects 106-120, wherein the composition further comprises at least one additional material selected from a phase-changing material, silica, photocatalytic nanoparticles, a second biopolymer material, a flame retardant, and any combination thereof.

[0279] Aspect 122. The composition of any one of aspects 106-121 , wherein the composition comprises the biopolymer and the plasticizer; wherein the biopolymer comprises nanocellulose in the form of cellulose nanofibrils, cellulose nanocrystals, or a combination thereof and the plasticizer comprises the anionic cellulose derivative, the nonionic cellulose derivative, or a combination thereof.

[0280] Aspect 123. The composition of aspect 122, wherein the composition further comprises at least one phase-changing material at a weight ratio of phase-changing material to nanocellulose of about 1:2 to about 4:5.

[0281] Aspect 124. The composition of aspect 123, wherein the at least one phase-changing material is selected from the group consisting of eutectics, salt hydrates, organic materials, and high-temperature salts.

[0282] Aspect 125. The composition of aspect 123, wherein the at least one phase-changing material is selected from the group consisting of sodium acetate, 1,2-benzisothiazol-3(2H)- one, and a combination thereof.

[0283] Aspect 126. The composition of any one of aspects 122-125, wherein the composition further comprises from about 1% to about 10% silica by weight.

[0284] Aspect 127. The composition of any one of aspects 106-122, wherein the composition comprises the biopolymer material and the plasticizer; wherein the biopolymer material comprises algal biomass and the plasticizer comprises the anionic cellulose derivative, the nonionic cellulose derivative, or a combination thereof.

[0285] Aspect 128. The composition of aspect 127, wherein the algal biomass is a cyanobacteria.

[0286] Aspect 129. The composition of aspect 127, wherein the algal biomass is a nostoc cyanobacteria.

[0287] Aspect 130. The composition of any one of aspects 127-129, wherein the composition is from about 0.1% to about 70% of algal biomass by weight.

[0288] Aspect 131. The composition of any one of aspects 127-130, wherein the composition further comprises the biopolymer comprising silk fibroin.

[0289] Aspect 132. The composition of aspect 131, wherein the composition is from about 10 wt% to about 99 wt% silk fibroin by weight.

[0290] Aspect 133. The composition of any one of aspects 106-120, wherein composition comprises the biopolymer and the crosslinking agent; wherein the biopolymer comprises nanocellulose in the form of cellulose nanofibrils, cellulose nanocrystals, or a combination thereof and the crosslinking agent comprises chitosan.

[0291] Aspect 134. The composition of aspect 133, wherein the composition further comprises the biopolymer material comprising wool fiber.

[0292] Aspect 135. The composition of aspect 134, wherein the composition is from about 0.1% to about 10% of wool fiber by weight.

[0293] Aspect 136. The composition of aspect 134 or aspect 135, wherein the composition has a thermal resistance of greater than about 2 °C m2 / W.

[0294] Aspect 137. The composition of aspect 133, wherein the composition further comprises the plasticizer comprising glycerol.

[0295] Aspect 138. The composition of aspect 137, wherein the composition has a water absorption capacity of about 30 g of water / g of the composition to about 65 g of water / g of composition.

[0296] Aspect 139. The composition of aspect 133, wherein the composition further comprises photocatalytic nanoparticles.

[0297] Aspect 140. The composition of aspect 139, wherein the photocatalytic nanoparticles are titanium oxide nanoparticles.

[0298] Aspect 141. The composition of aspect 139 or aspect 140, wherein the composition comprises the photocatalytic nanoparticles in a weight ratio of chitosan to photocatalytic nanoparticles of about 1 :4 to about 4: 1.

[0299] Aspect 142. The composition of any one of aspects 106-120, wherein composition comprises the biopolymer material and the crosslinking agent; wherein the biopolymer material comprises lignocellulosic biomass and the crosslinking agent comprises chitosan.

[0300] Aspect 143. The composition of aspect 142, wherein the lignocellulosic biomass comprises banana biomass.

[0301] Aspect 144. The composition of aspect 143, wherein the composition is from about 0.1% to about 10% of the banana biomass by weight.

[0302] Aspect 145. The composition of any one of aspects 142-144, wherein the composition further comprises the biopolymer comprising silk fibroin.

[0303] Aspect 146. The composition of aspect 145, wherein the composition is from about 10 wt% to about 99 wt% silk fibroin by weight.

[0304] Aspect 147. The composition of any one of aspects 133-146, wherein the crosslinking agent further comprises phytic acid.

[0305] Aspect 148. The composition of aspect 147, wherein the composition is from about 0.1% to about 10% of phytic acid by weight.

[0306] Aspect 149. The composition of any one of aspects 142-144, wherein the composition further comprises photocatalytic nanoparticles.

[0307] Aspect 150. The composition of aspect 149, wherein the photocatalytic nanoparticles are oxide nanoparticles.

[0308] Aspect 151. The composition of aspect 150, wherein the oxide nanoparticles are titanium oxide nanoparticles.

[0309] Aspect 152. The composition of any one of aspects 133-146, wherein the composition further comprises a flame retardant.

[0310] Aspect 153. The composition of aspect 152, wherein the flame retardant is selected from sodium bicarbonate, ammonium polyphosphate, melamine, zinc borate, hydrated magnesium hydroxide, aluminum trihydrate, a bio-based polyphosphate, a tannin, a silica aerogel, clay nanoparticles, borax, an intumescent composition, or a combination thereof

[0311] Aspect 154. The composition of aspect 152 or aspect 153, wherein the composition is from about 0.1% to about 20% of the flame retardant by weight.

[0312] Aspect 155. The composition of aspect 152 or aspect 153, wherein the composition is from about 0.1% to about 10% of the flame retardant by weight.

[0313] Aspect 156. The composition of any one of aspects 106-155, wherein the composition has a porosity of greater than about 85%.

[0314] Aspect 157. The composition of any one of aspects 106-155, wherein the composition has a porosity of from about 85% to about 95%.

[0315] Aspect 158. The composition of any one of aspects 106-157, wherein the composition has a specific surface area of at least 200 m2 / g.

[0316] Aspect 159. The composition of any one of aspects 106-157, wherein the composition has a specific surface area of about 200 m2 / g to about 1500 m2 / g.

[0317] Aspect 160. The composition of any one of aspects 106-159, wherein the composition has an apparent density of about 0.003 g / cm3to about 0.5 g / cm3.

[0318] Aspect 161. A composition, comprising: a biopolymer, a biopolymer material, or a combination thereof; and an additional agent selected from a plasticizer, a crosslinking agent, or a combination thereof; wherein the plasticizer comprises an anionic cellulose derivative, a nonionic cellulose derivative, or a combination thereof; and wherein the crosslinking agent comprises chitosan, phytic acid, citric acid, tannic acid, calcium chloride, glutaraldehyde, transglutaminase, sodium alginate, lignin, a polyphenol, genipin, or a combination thereof.

[0319] Aspect 162. The composition of aspect 161 , wherein the plasticizer comprises carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, and any combination thereof.

[0320] Aspect 163. The composition of aspect 161 or aspect 162, wherein the composition is from about 0.1% to about 20% plasticizer by weight.

[0321] Aspect 164. The composition of aspect 161 or aspect 162, wherein the composition is from about 1% to about 15% plasticizer by weight.

[0322] Aspect 165. The composition of any one of aspects 161-164, wherein the composition is from about 0.1% to about 10% crosslinking agent by weight.

[0323] Aspect 166. The composition of any one of aspects 161-164, wherein the composition is from about 0.1% to about 5% crosslinking agent by weight.

[0324] Aspect 167. The composition of any one of aspects 161-166, wherein the biopolymer comprises lignin, cellulose, hemicellulose, nanocellulose, silk fibroin, or any combination thereof.

[0325] Aspect 168. The composition of any one of aspects 161-167, wherein the composition is from about 0.01% to about 99% of the biopolymer by weight.

[0326] Aspect 169. The composition of any one of aspects 161-167, wherein the composition is from about 20% to about 50% of the biopolymer by weight.

[0327] Aspect 170. The composition of any one of aspects 161-167, wherein the composition is from about 60% to about 80% of the biopolymer by weight.

[0328] Aspect 171. The composition of any one of aspects 161-170, wherein the biopolymer material comprises algal biomass, lignocellulosic biomass, or a combination thereof.

[0329] Aspect 172. The composition of any one of aspects 161-171 , wherein the composition is from about 0.1% to about 90% of the biopolymer material by weight.

[0330] Aspect 173. The composition of any one of aspects 161-171 , wherein the composition is from about 0.1% to about 70% of the biopolymer material by weight.

[0331] Aspect 174. The composition of any one of aspects 161-171, wherein the composition is from about 0.1% to about 50% of the biopolymer material by weight.

[0332] Aspect 175. The composition of any one of aspects 161-174, wherein the composition further comprises at least one additional material selected from a phase-changing material, silica, photocatalytic nanoparticles, a second biopolymer material, and any combination thereof.

[0333] Aspect 176. The composition of any one of aspects 161-175, wherein the composition comprises the biopolymer and the plasticizer; wherein the biopolymer comprises nanocellulose in the form of cellulose nanofibrils, cellulose nanocrystals, or a combination thereof and the plasticizer comprises the anionic cellulose derivative, the nonionic cellulose derivative, or a combination thereof.

[0334] Aspect 177. The composition of aspect 176, wherein the composition further comprises at least one phase-changing material at a weight ratio of phase-changing material to nanocellulose of about 1 :2 to about 4:5.

[0335] Aspect 178. The composition of aspect 177, wherein the at least one phase-changing material is selected from the group consisting of eutectics, salt hydrates, organic materials, and high-temperature salts.

[0336] Aspect 179. The composition of aspect 177, wherein the at least one phase-changing material is selected from the group consisting of sodium acetate, 1,2-benzisothiazol-3(2H)- one, and a combination thereof.

[0337] Aspect 180. The composition of any one of aspects 176-179, wherein the composition further comprises from about 1% to about 10% silica by weight.

[0338] Aspect 181. The composition of any one of aspects 161-176, wherein the composition comprises the biopolymer material and the plasticizer; wherein the biopolymer material comprises algal biomass and the plasticizer comprises the anionic cellulose derivative, the nonionic cellulose derivative, or a combination thereof.

[0339] Aspect 182. The composition of aspect 181, wherein the algal biomass is a cyanobacteria.

[0340] Aspect 183. The composition of aspect 181, wherein the algal biomass is a nostoc cyanobacteria.

[0341] Aspect 184. The composition of any one of aspects 181-183, wherein the composition is from about 0.1% to about 70% of algal biomass by weight.

[0342] Aspect 185. The composition of any one of aspects 181-184, wherein the composition further comprises the biopolymer comprising silk fibroin.

[0343] Aspect 186. The composition of aspect 185, wherein the composition is from about 10 wt% to about 99 wt% silk fibroin by weight.

[0344] Aspect 187. The composition of any one of aspects 161-174, wherein composition comprises the biopolymer material and the crosslinking agent; wherein the biopolymer material comprises lignocellulosic biomass and the crosslinking agent comprises chitosan.

[0345] Aspect 188. The composition of aspect 187, wherein the lignocellulosic biomass comprises banana biomass.

[0346] Aspect 189. The composition of aspect 188, wherein the composition is from about 0.1 % to about 10% of the banana biomass by weight.

[0347] Aspect 190. The composition of any one of aspects 187-189, wherein the composition further comprises the biopolymer comprising silk fibroin.

[0348] Aspect 191 . The composition of aspect 190, wherein the composition is from about 10 wt% to about 99 wt% silk fibroin by weight.

[0349] Aspect 192. The composition of any one of aspects 187-189, wherein the composition further comprises photocatalytic nanoparticles.

[0350] Aspect 193. The composition of aspect 192, wherein the photocatalytic nanoparticles are oxide nanoparticles.

[0351] Aspect 194. The composition of aspect 193, wherein the oxide nanoparticles are titanium oxide nanoparticles.

[0352] Aspect 195. The composition of any one of aspects 161-194, wherein the composition has a porosity of greater than about 85%.

[0353] Aspect 196. The composition of any one of aspects 161-194, wherein the composition has a porosity of from about 85% to about 95%.

[0354] Aspect 197. The composition of any one of aspects 161-196, wherein the composition has a specific surface area of at least 200 m2 / g.

[0355] Aspect 198. The composition of any one of aspects 161-196, wherein the composition has a specific surface area of about 200 m2 / g to about 1500 m2 / g.

[0356] Aspect 199. The composition of any one of aspects 161-198, wherein the composition has an apparent density of about 0.003 g / cm3 to about 0.5 g / cm3.

[0357] Aspect 200. The composition of any one of aspects 161-199, wherein the composition has an intrinsic thermal resistance of about 0.001 °C m2 / W to about 0.02 °C m2 / W.

[0358] From the foregoing, it will be seen that aspects herein are well adapted to attain all the ends and objects hereinabove set forth together with other advantages which are obvious and which are inherent to the structure.

[0359] While specific elements and steps are discussed in connection to one another, it is understood that any element and / or steps provided herein is contemplated as being combinable with any other elements and / or steps regardless of explicit provision of the same while still being within the scope provided herein.

[0360] It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims.

[0361] Since many possible aspects may be made without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings and detailed description is to be interpreted as illustrative and not in a limiting sense.

[0362] It is also to be understood that the terminology used herein is for the purpose of describing particular aspects only, and is not intended to be limiting. The skilled artisan will recognize many variants and adaptations of the aspects described herein. These variants and adaptations are intended to be included in the teachings of this disclosure and to be encompassed by the claims herein.

[0363] Now having described the aspects of the present disclosure, in general, the following Examples describe some additional aspects of the present disclosure. While aspects of the present disclosure are described in connection with the following examples and the corresponding text and figures, there is no intent to limit aspects of the present disclosure to this description. On the contrary, the intent is to cover all alternatives, modifications, and equivalents included within the spirit and scope of the present disclosure.G. EXAMPLES1. Aerogels and Foams from Lignocellulosic and Protein Sources Examples

[0364] Introduction. Significant aerogel properties include high porosity (usually more than 90%), low density (0.003-0.5 g / cm3), and high specific surface area (200-1500 m2 / g) [1-3], Aerogels are a breakthrough material developed for versatile applications that deliver characteristics such as lightweight, superabsorbent, [4-7] and thermal insulation, [8-11] and facilitate efficient reactive surfaces. Due to the aforementioned characteristics, aerogels are suitable for various applications in electrical, automotive, space, bio-medical, pharmaceutical, and cosmetics fields, the construction sector, wastewater treatments to mitigate environmental pollution, catalysis, and in food industry [12-16],

[0365] Aerogels can be prepared from hydrogels, xerogels, cryogels, and other aerogel- related materials

[0017] , Conventional aerogels are made from supercritical drying of gels [17- 19] following the Sol-gel process [17,18], In the aerogel manufacturing process from the solgel technique, critical processing measures are required to retain the shape and porosity while solvent evaporation from the inner and outer surfaces of the aerogels

[0020] , The nature of the precursors, chemical reaction, and process parameters determine the maximum porosity of aerogel structure [20-24], Based on the significance of aerogel microstructure, aerogels can be divided into microporous (<2 nm) aerogels, mesoporous (2~50 nm) aerogels, and mixed- porous aerogels [2,26], Two drying mechanisms are frequently applied in synthesizing aerogels in the modern context; 1). Supercritical drying for gels of silicon and other lipophilic materials [20, 27-29] and 2). Freeze-drying for hydrogels and other compatible materials [SO- 33]. Conversely, conventional drying can deliver more than 50% porosity; in this approach, the porosity must be further improved by enhancing colloidal foam stability generating macrovoids and macroporous structure [34,35], Functional characteristics of aerogels are interlinked and related to their material chemistry and origin; there are organic, inorganic, and hybrid aerogels. Thereby, the aerogel market can be segmented into Silicon, polymer, Carbon, metal- oxides, etc.

[0014] , Classification of polymeric aerogels can further extend into synthetic,biopolymers, and bio-based

[0036] . Using nanomaterials enhances pivotal performances integrated with three-dimensional structural attributes, “aerogen structural characteristics” defined by high aspect ratio and stable pore structure. A stable porous structure is a collaborative network of material interspaces made from globules (in silica and polyurea aerogels) or a combination of fibers (in cellulose, chitosan, and alginate aerogels) [2, 16], Specific surface area and pore size distribution directly indicate “aerogen structure,” also interlinked with other processing measures. Nanomaterials embody stable mesoporous structure and narrow size distribution of pore sizes [37, 38],

[0366] The Aerogel industry shows promising growth and expects the market value to reach a CAGR of around 9% during 2019-2024

[0037] , However, the continuous growth of the aerogel industry is somewhat affected by high manufacturing costs associated with drying processes and excessive solvent usage in the sol-gel process, specifically in the market’s dominant Silicon-based aerogels [39,40], Due to poor mechanical strength and dust contamination, some industries are concerned about the limitations of using aerogels for their intended applications, such as aerospace or pharmaceuticals [40, 41],

[0367] Due to the emerging environmental concerns, supply chain crisis, and other concurrent effects, there is a need for sustainable approaches to create green chemistry in the aerogel industry, and bio-based aerogels from renewable sources are widely being studied as a sustainable replacement. Hydrogels of natural polymers are perfect green alternatives for the aerogel industry to minimize solvent use and adopt a commercially viable freeze-drying process to retain a mesoporous stable “aerogel structure” with high porosity. The possibility of using hydrogels for aerogels from cellulose, lignocellulosic sources, alginates, and carbohydrates is being researched to fulfill the sustainable demands of the aerogel industry. Making biopolymers more desirable for interdisciplinary and multidisciplinary scientific research, utilizing natural or bio-based polymers deliver functionalities such as bioactivity, biocompatibility, biodegradability, and unique chemistry.

[0368] Herein, aerogel applications are explored in functional textile coatings for thermal insulation to facilitate thermal regulation in human homeostasis [42, 43] and the super absorbency of aerogel coatings [6, 44, 45] are evaluated. Thermal regulating textiles and coatings are widely researched in textile engineering to address performance and comfort needs [43, 46, 47], This design concept includes incorporating a lignocellulosic aerogel layer between two cotton layers to construct a sandwich-like structure. Nanocellulose (NC) from wood pulp is one lignocellulosic source that is used, along with the lignocellulosic process wastes such as cotton noil and sawdust. Lignocellulosic process wastes align with the principles of green chemistry and promote waste to product concept and can be considered a value addition that makes cost factor favorable. Cotton noil is a process waste of cotton yarn combing process and may have issues of contamination and inconsistency [48, 49], A significant fraction of unrecordable sawdust is being released from the timber and forestry industries. Sawdust is a mixture of different wood sources widely used for wood cement, glues,and concretes [50, 51], The processability of sawdust is constrained by its composition and contamination.

[0369] Apart from those, aerogels from hemp fiber are of interest for the high mechanical and structural strength of bast fibers

[0052] , Nanocellulose is a one-dimensional nanomaterial used for hydrogels form processed from abundantly found cellulosic sources. Lignocellulosic biomass undergoes several pre- and post-processing in the NC production to maintain purity and consistency in properties. NC is mechanically processed nanofibrillated cellulose (NFC) and nanocrystalline cellulose (NCC) is from chemical and enzymatic processing

[0035] , For biomedical applications, BNC gives hydrogels with the highest purity

[0015] ,

[0370] Lignocellulosic aerogels middled with cotton fabrics sandwich structure has resulted in a 3D compact unit which is a biodegradable and sustainable green design concept for thermal insulation and super absorbency. The freeze-drying process has been optimized, excluding liquid nitrogen for rapid cooling, to reduce manufacturing cost. Herein the flexibility of using two types of NCs along with other lignocellulosic hydrogels, NFC and NCC, is explored. Fibrous spaces in NFC and spaces in NCC structures would contribute to a mesoporous 3D “aerogen structure” with high porosity and surface area. The lightweight characteristic of the NC aerogel inner middle layer reduces the 3D sandwiched density of the unit more than three times the cotton fabrics, improving its comfort aspects.

[0371] For further enhancements in thermal regulation of the functional aerogel coatings, NC aerogel layers are filled with phase-changing materials as an efficient thermal energy storage / release element [53-56], Herein, thermal insulation of the compacted cotton-aerogel 3D structure can be obtained by preventing heat diffusion from the body to the outside in cold weather, preserving the cooling effect when the body is warmer. The cooling effect is a critical comfort measure for durable day-to-day clothing. Fundamentals of the cooling effect of the cotton-aerogel unit can be interpreted through sweat release (heat-release) from capillary action, wicking, and evaporation (see FIGS. 1A and 1 B) as the process involves [42, 47, 57- 59]; 1). Hydrophilic cotton fibers that favor sweat absorbance, 2). Wicking facilitates sweat migration against a gradient, and 3). Heat is released through moisture evaporation from the outer surfaces. NC aerogel layer consists of nanoscale fibers similar to cotton fibers and acts as super-adsorbents. Thereby, the middle layer may not disturb capillary motions and wicking established by the cotton fabric layers.

[0372] When exposed to cold weather, the body diffuses the heat outside through radiation and conduction [60-63], Thereby, thermal insulation from clothes acts as protective barriers in cold temperatures. Cotton fabrics are constructed from cellulosic fibers with low thermal conductivity between 0.026-0.065 W / mK

[0064] , Thermal conductivity is expected to be further reduced by having a nanoscale NC cellulosic fibrils with similar material properties. The mesoporous NC aerogel middle layer has entrapped dead-air pockets that improve insulation properties against heat conduction and radiation measures. Thermal conductivity is the critical and inverse measurement of thermal insulation. Phase-changing materials (PCM) have beenincorporated into the middle aerogel layer to obtain efficient thermal regulation across the layers and to accelerate heat exchange in thermal regulation. Silica aerogel powder at different loadings was added to the NC and PCM formulations to design hybrid aerogel middle layers to assess the effect of thermal conductivity against hybrid materials.

[0373] The aerogel features can be combined with the functional and conformal aspects of thermal regulating coatings and super absorbency with lightweight, high porosity, and large surface area for diverse applications. Thereby, developed cotton-aerogel layered structures can be used as clothing, bedding, thermal insulating building material, and for many applications in water purification.

[0374] Materials and Methods - Materials and Reagents: Cellulose powder (Weyerhaeuser); carboxymethyl cellulose (CMC, MM=90,000 g / mol, Sigma-Aldrich); 400 GSM 100% woven fabrics (from Testfabrics Inc), 10.wt% NFC Exilava F 01-V (from Borregaard, Norway), 6.wt% CelluForce NCC® NCV100-NAL90, kraft pulp (Weyerhaeuser, Dacula, GA, USA), hemp, sawdust and cotton noil were used as received. Phase changing material: 1 ,2-Benzisothiazol- 3(2H)-one, EnFint R Slurries 28RSS, 2O.wt%. Silica aerogel: Enova® Aerogel IC3100 Particles.

[0375] Preparation of initial aerogel samples for pore analysis: Aerogels of NFC (3.wt%) and NCC (6.wt%) were aerated for 3 min using IKEA high-speed stirrer at 10,000 rpm. Once a stable foam dispersion was prepared, it was transferred into 20ml glass scintillation vials. The sealed vials were then frozen at -20°C for a minimum of 6 hours. Following this, the samples were freeze-dried at -40°C and 1 mbar pressure until they were completely dry. This process took between 4-8 hours, depending on the sample size, and was carried out using the LABCONCO freeze drying system, FREEZONE 4.5. After removal, the freeze-dried samples were desiccated for 4 hours prior to testing.

[0376] Preparation of Cotton-Aerogel 3D sandwich structures: Lignocellulosic hydrogels such as NFC or NCC were aerated for 3 minutes using an IKEA high-speed stirrer at 10,000 rpm to create a stable foam. This foam was then coated onto cotton fabrics using a micro-coater to a thickness of 3mm. Subsequently, an additional layer of cotton was carefully placed on top. The structures were then frozen at -20°C for a minimum of 6 hours. Following this, they were freeze-dried at -40°C and 1 mbar pressure until completely dry, which took between 4-8 hours depending on the sample size. This process was carried out using the LABCONCO freeze drying system, FREEZONE 4.5.

[0377] Pore size and filter flow efficiencies of the initial NC aerogels’. Were analyzed using porometer, PMI, l-Pore.

[0378] Thermal conductivity: Following ASTM F-1868 method, the dry thermal conductivity of 2.5* 2.5 inches aerogel samples was measured from Thermetrics sweating guarded hotplate.

[0379] Fourier-Transform Infrared Spectroscopy (FT-IR): Structural confirmation of lignocellulosic sources was obtained through FTIR analysis (Perkin Elmer 6700 FT-IR), andabsorbance patterns were assessed carefully in the range of 600-3500cnr1at 128 scanning cycles.

[0380] Moisture content: Approximately 5g of each lignocellulosic material was dried overnight at 120°C for 24 hours. From before and after weight difference moisture content was calculated.

[0381] Oil and water absorbency: In accordance with ASTM D570, each aerogel 3D unit (1 inch*1 inch) was first dried in an oven at a specified temperature and time, then weighed. The units were then immersed in 50 ml of water or heavy mineral oil until equilibrium was reached. After immersion, the units were dried and reweighed. The absorbency was calculated based on the variance in weight before and after immersion.

[0382] Hydrogel making from different lignocellulosic sources: 0.125 g of carboxymethyl cellulose was dispersed in 500 ml deionized water at 100 °C, and 10g of lignocellulosic material was dispersed at 200 rpm for 15 min. Then the slurry was introduced to APV 1000 homogenizer at 100°C. The slurry was passed through 500 bar pressure and continued homogenizing until it reached its gelling point. The process begins at a pressure of 500 bar. However, the gel point, which is the point at which the slurry transitions from a liquid to a gel, can vary between 600 and 700 bar. This variation in the gel point is dependent on the specific batch being processed. The slurry, a semi-liquid mixture, is typically at a temperature of around 90°C. However, this temperature decreases after the reblending process. At the gel point, the temperature is often relatively high. It’s important to note that the gel point can vary depending on the type of lignocellulosic biomass used. A temperature range of 75-85°C is one example of a safe and effective temperature for the process. This temperature range also contributes to lower energy consumption, making the process more efficient.

[0383] Scanning Electron Microscopy (SEM) Imaging: Microtomes of the 3D aerogel sandwich structures were prepared using a sharp blade in order to obtain a crisp crosssection. After that, the films were immersed in liquid nitrogen for shape retention. Microtomes of aerogel cross-sections were gold-coated at 20mA for 90 seconds. Then cross-sections were examined using the FEI Teneo FE-SEM instrument to assess pore distribution.

[0384] Results and Discussion - Initial aerogels: Initial aerogels of NC showcase higher specific area, lower apparent density, and high porosity (greater than 90%), complying with the critical measures of aerogels, as given in Table 1 . Aerogels of NFC appear to deliver high porosity in comparison to NCC. FIGS. 1C and 1 D show images of initial aerogel samples. The pore size distributions of NFC and NCC aerogels are broad bell-shaped in nature and skewed to the right (see FIGS. 1 E and 1 F). NFC pore distribution ranges between 0.60 nm to 2.0 nm and is reasonably mesoporous. NCC aerogels have exhibited pore size distribution somewhat in the regime of meso-macroporosity, 2.5-20 nm (see FIG. 1 F).Table 1. Characteristic measures of initial aerogels of NC, evaluated against its specific area, apparent density, and porosity.

[0385] Thickness, density, and conductivity: In assessing thermal insulation properties of Cotton-aerogel sandwich structures, several variables are identified, Ref of different textiles, the thickness of the compacted structure, and material characteristics such as topology, surface packing, and yarn characteristics. Incorporating the NC aerogel middle layer has drastically reduced the apparent density of cotton aerogel units in FIG. 2A. Compared to 100% cotton two layers, 1mm of aerogel middle layer would lower the apparent density approximately by 60%, and 4mm of aerogel layer would lead to an apparent density drop of more than 75%, making insulation material lightweight.

[0386] Different 3D structures: Thermal resistance is reasonably interdependent on the thickness, and insulation. Ref values appear to be lower than the two layers of cotton at specific thicknesses. However, a slight decrease in insulation properties at greater thicknesses can be noticed, above 1.6 mm, most likely due to compact packing of the aerogel layer, leading to inefficient porosity and promoting heat conduction across, in FIG. 2B. Thermal conductivity is a complex material property governed by chemistry, processing, topology, and surface effects [65-68], If the middle layer of aerogel becomes thicker, it can reduce thermal conductivity and improve insulation properties by creating less effective heat transfer paths through solid material (see FIG. 2B). In FIG. 2B, to calculate Ref, it is assumed that the boundary layers of the bare plate and boundary layers of the fabric test specimen are equal.

[0387] PCM filled NC aerogels: PCM-filled aerogels may deliver a superior cooling effect than neat NC aerogels (FIGS. 3A-3C). Biobased aerogels are known for poor structural strength (FIG. 3C). NC and silicon hybrid aerogels may improve the mechanical, structural, shape memory, solvent resistance, and dimension stability of NC aerogels [36, 69, 70], Thereby, the durability and reusability of NC aerogels can be extended from hybrid aerogels (FIG. 3C).

[0388] PCMs are temperature sensitive and have a specific melting and crystallization temperature range that defines performance [71 , 72], The melting peak is 26 °C - 40 °C, and the crystallization peak is 27 °C - 15 °C

[0073] , At room temperature 20 °C - 25 °C, PCMs are beyond their effective melting range to absorb heat due to not having enough heat flux across the specimen. Hence, Ref values are somewhat scattered, and the PCM effect in heat exchange could not be observed in FIG. 4A. Under test conditions aligned within the human body temperature, 37 °C ASTM F-1868, a clear trend can be seen, FIG. 4B. At the thermal equilibrium, in FIG. 4C, there is a correlation and noticeable trend in Ref of PCM added NCC aerogels. Loading PCM reduces the intrinsic thermal resistance of the 2C+NC aerogel units by 25% to 45%, and this is subjected to the PCM loading ratio to the NCC matrix in FIG. 4C.PCM-filled NCC aerogels show a constant heat exchange for a prolonged time, at least last for 2 hours, FIG. 4D.

[0389] Hybrid aerogels: NC hydrogel and Silica aerogels have incompatible chemistry. Hence, Ref values appeared to be less conclusive and show a nonlinear pattern affected by poor interfacial bonding and incompatibility between NC hydrogel and Silica aerogel, but at lower loading of Silica aerogel. However, at higher loading, the Ref values exhibit the highest value, FIG. 5A and FIG. 5B, at higher loadings mixing and aeration were less efficient.

[0390] Lignocellulosic aerogels: Lignocellulosic sources involved in this study have cellulose as their major component, with the presence of p (1-4) glycosidic linkages in FT-IR (FIG. 6A). Thereby, hydrogels of NC, Hemp, and cotton noil may have similar colloidal chemistry. Apart from having cellulose, sawdust hydrogel chemistry is influenced by hemicellulose (a1 ) and lignin (a2 and a3), as indicated in FIG. 6A. The moisture content of each lignocellulosic source confirms FT-IR profiles. NC from wood pulp exhibited the highest moisture content caused by extreme hydrophilicity, followed by lower moisture content in sawdust due to lignin and hemp being a bast fiber (FIG. 6B). Proposed lignocellulosic sources have favorable hydrogel chemistry for aerogels. Based on Ref at thermal equilibrium in FIG. 6C, sawdust and hemp show lower thermal resistance Ref, up to 10%, than wood pulp based NC aerogels which can be explained by inherited structural chemistry in FT-IR.

[0391] Structural porosity, composition, apparent density, modifications, specific surface area, and processing are the main factors that govern the superabsorbency of aerogels [74, 75], Oil absorbency of hydrophobized nanocellulose and sawdust is higher than their water absorbency, favored by their chemical structures (see FIGS. 7A-7C). Hemp exhibits the highest degree of water and oil absorbency. Hence, there is vast potential in using superabsorbent characteristics of lignocellulosic aerogels for waste treatment, pollutants removal in water, and oil removal in water. Sawdust has been used for the removal of various pollutants such as copper (II), heavy metals, dye, and phenol from industrial waste sources [76-79], For such applications, aerogels of sawdust can deliver excellent pollutant removal remedies.

[0392] Scanning Electron Microscope (SEM) Imaging: The intrinsic pore structure of aerogels is a construction of differently shaped pores and pore size distribution linked to the composition of the lignocellulosic biomass (see FIGS. 8A-8C). Cooling, formulation, and other processing conditions used in aerogel making play a critical role in pore structure retention and characteristics [118, 31 , 80, 81], Aerogels are characterized by the nature of the pores and pore size distribution as they govern mechanical [82-85], superabsorbent [5, 86], and other key performances [8, 87-89],

[0393] Pore size distribution from the porometer analyses reasonably estimates the pore size distribution across a given surface area of aerogels [90-92], SEM would give inferences to structural porosity and visual evidence to justify the pore shape and arrangement across a specimen [93, 94], Aerogels from natural lignocellulosic origin would have non-uniformly shaped 3D conformation after the freeze-drying process, as in FIGS. 9A, 9C, and 9E. Basedon porometer results, NC, PCM-filled NC, and hybrid aerogels from Silicon and PCM have mixed-mesoporous distribution as in FIGS. 9B, 9D, and 9F. In these aerogels (NC, PCM-filled NC) and NC+PCM+Si hybrid), the nature of pores and pore size distributions differ by the variations in their formulation. Hence, as per FIGS. 9A and 9B, NC pore size is relatively mixed porous with functional pore size distribution ranging from 1.5-30pm. In SEM of filled aerogel (NC+PCM), pore sizes are getting larger, losing structural porosity, as given in FIG. 9C. In the filled aerogel (NC+PCM), functional porosity drops with loading bulky PCM as pore sizes range from 2.5-37.5 pm, as in FIG. 9D. This trend continues in hybrid aerogels where Si and PCM are incorporated. SEM images further justify having large pore sizes that make losing structural porosity with loading PCM and PCM+Si, as in FIG. 9E. In hybrid aerogel (NC+PCM+Si), pore sizes vary from 20-350 pm, as indicated in FIG. 9F.

[0394] The lignocellulosic aerogels used in the study are constituted by a fibrillar natural fiber network comprising an array of fibers of different sizes. Cellulose, Hemp, Cotton Noil, and Wood / Sawdust are all lignocellulosic sources of semicrystalline origin. However, the literature suggests that the cellulose content and concentration play a key role in structural strength and retaining stable pores in aerogels. Cross-sectional pore analysis depends on the structural integration and composition of lignocellulosic sources used for making aerogels under the same freeze-drying, formulation, and handling conditions in this study.Table 2. Heterogeneous composition of various lignocellulosic sources [528-531],

[0395] Based on the SEM image, FIG. 10A, Cotton Noil, which has a similar origin to cotton, shows a mixed porous fibrillar aerogel structure having irregularly shaped pores in the range 4.5-30pm, , FIG. 10B. Sawdust has a relatively higher fraction of lignin, and pectin also has undergone minimum pre-post treatments, Table 2. The fibrillar aerogel structure of Sawdust shows smaller structural pores in SEM, FIG. 10C, represented by functional pore distribution in the range of 1.6-39.3pm. The complex pore distribution of Sawdust aerogels can interrelate with its efficient superabsorbent characteristics having a high volume of pores, , FIG. 10D. The unique origin and structural composition of Hemp, as given in Table 2, have imparted comparatively crystalline aerogel structure, in , FIG. 10E with regularly shaped and differentlysized, organized pore arrangement as given in , FIG. 10F. Pores of Hemp range from 6.5- 43.3 pm and differ from the fibrillar pore distribution of aerogels from other lignocellulosic sources, Cotton Noil, and Sawdust, with irregular pore shape and non-ordered pore arrangement.

[0396] Additional Data - Silk-based aerogel for oil absorption: Silk, a protein fiber, is predominantly produced by certain insect larvae, particularly the Bombyx mori silkworm, for cocoon creation. Composed mainly of fibroin, silk is celebrated for its sleek, lustrous texture and remarkable durability. Silk is an exceptional material with both hydrophobic (waterrepelling) and hydrophilic (water-attracting) properties, attributed to its molecular structure. The silk protein consists of hydrophobic and hydrophilic components, enabling complex interactions with water. The beta-sheet structures in silk are asymmetrical, with large hydrophobic regions interspersed with smaller hydrophilic ones, contributing to its distinctive properties. This asymmetry allows silk to exhibit both hydrophobic and hydrophilic characteristics, attracting or repelling water based on specific conditions and the substances involved.Table 3. Silk aerogel composition.

[0397] Carboxymethyl cellulose was dissolved in 500 ml deionized water at 100 °C, and 10g of silk fibroin material was mixed at 300 rpm for 15 min. Then the mixture was transferred to APV 1000 homogenizer at 100°C. The mixture was subjected to 700 bar pressure and kept homogenizing until it became gel-like. In this experiment decreasing concentration of silk hydrogel is further mixed with the increasing concentration of the CMC up to 33.33% (Table 3). In preliminary studies all of the iterations showed the high hydrophobic characteristics, giving the aerogel fluffier characteristics which could be observed in the side view in FIGS. 11A-11C.

[0398] Silk and cellulose-based aerogel: Silk’s capacity to regulate water content is crucial for its inherent functions, like the silk fiber production by silkworms. When silk is used in different cellulose concentrations as the matrix, its properties can transition from being hydrophilic to a hydrophobic aerogel, enhancing its specificity for oil absorption. Moreover, silk aerogel exhibits superior oil absorption relative to its weight, allowing it to confer these properties to composite aerogels.

[0399] Silk and cellulose-based algae aerogel: Incorporating algae into an aerogel matrix can lead to the development of a hydrophobic aerogel with superior oil absorption properties. Algae, being renewable and sustainable, serves as an eco-friendly resource that can be sustainably harvested. The inclusion of algae in the aerogel matrix aligns with the circular economy principles, promoting resource efficiency by using biomass resources that might otherwise be wasted.

[0099] , Components derived from algae can be tactically utilized to alter the aerogel’s hydrophobic or hydrophilic properties, thereby adjusting its porosity and surface area. This customization not only boosts the aerogel’s performance but also provides precise control over its attributes, rendering it ideal for specific applications

[0100] ,

[0400] The versatility of the aerogel extends to numerous fields such as adsorption processes, drug delivery systems, and soil-fertilizer delivery systems. The combination of silk and cellulose, along with the beneficial properties of algae, results in a composite material that attains hydrophobicity for specific oil absorption. This material represents a sustainable and functional solution with a wide range of potential applications. This innovative method not only meets specific material performance objectives but also aligns with the broader goals of environmentally friendly, sustainable material development.Table 4. Silk based algae aerogel composition.

[0401] Chlamydomonas, a unicellular photosynthetic alga, is used in this experiment to study the properties of aerogel after addition to the silk hydrogel slurry. The synthesized aerogel has a characteristic green look due to the cellulose content of the unicellular algae (FIGS. 12A- 12C). No previous data was found on adding unicellular algae directly in its wet form into the hydrogel to make aerogel, so the major concentration was selected to study the properties of aerogel (Table 4). The aerogel maintained its fluffiness with and without algae, proving the presence of many microporous structures that could be observed through SEM. However, the structure becomes more brittle with the increasing concentration of algae wet weight.

[0402] Nostoc- different composition based hydrogel - aerogel: Nostoc is a type of cyanobacteria, also known as blue-green algae, that has been studied for various applications. One of its applications is in the creation of aerogel beads that can be used to remove cadmium (Cd(ll)). Additionally, Nostoc sp. HK-01 , a type of cyanobacteria tested for cell survival during the Tanpopo mission, has demonstrated its high tolerance to the space environment

[0101] ,

[0403] Incorporating Nostoc into aerogels could be beneficial due to the unique properties of aerogels and the characteristics of Nostoc. Aerogels, with their high porosity, low density, and large surface area, are suitable for a variety of applications, including insulation, environmental remediation, and drug delivery (see FIGS. 13A-13G). In a particular experiment, Nostoc is integrated into the aerogels, resulting in a potential biobased aerogel with improved environmental and functional properties. This could be advantageous in areas such as pollution control and biomedical applications. Moreover, the materials used in the experiment to create the Nostoc aerogel are also of note (see Table 5). They could serve as an effective alternative for oil waste absorption.Table 5. Heterogeneous composition of various polymer sources with algae ( Nostoc).

[0404] Hemp and lignin composite aerogel study: Hemp fibers were knife milled (Wiley Mini Mill) using a sieve size of 60 three times through. The grinded hemp powder was stored inside a convection oven at 60°C. Next, slurries were made from knife-milled powders to make a 2% weight / volume NFC hydrogel. These gels consisted of 10 grams of dry weight with varying amounts of cellulose and lignin, but a constant amount of carboxymethyl cellulose (CMC). 500 ml of water were used to prepare the slurry, and 1 ,25g of CMC was added as a dispersant to the powder. After the CMC dissolved, a predetermined amount of milled powder and lignin were added to the hot CMC solution. The slurry was mixed with a stirring rod at 700 rpm until the powder was completely dispersed. The mixing continued until the temperature reached 100 °C, and then the slurry was left to cool to 70 °C. At this point, the slurry was poured into the homogenizer and was homogenized for 20 mins. See FIGS. 14A-14G for depictions of the aerogels formed and Table 6 for further details regarding the aerogels.Table 6. 2% Hemp and lignin-based aerogel.

[0405] Banana stalk-based aerogel for oil absorption: Banana stalk waste, the discarded stems of banana plants, has garnered research interest for its potential applications in food packaging, bioplastics, organic fertilizers, and even vegan fashion. This study explored the use of banana stalk waste as a matrix material due to its oil absorption properties. By fabricating a 2% banana aerogel, we demonstrated its oil absorption capacity of 40 g / g, which is double that of standard synthetic oil absorbents, suggesting its potential as an efficient oil sorbent material.2. Banana Stalk-Based Aerogel for Photocatalytic Activity

[0406] Oxide nanoparticles have garnered substantial attention within the field of photocatalysis owing to their distinctive attributes that render them highly effective across diverse photocatalytic applications. Noteworthy features of oxide nanoparticles, contributing to their utility as photocatalysts, encompass their wide-ranging band gap energies dictating their light absorption capability, spanning from the ultraviolet (UV) to visible segments of the electromagnetic spectrum

[0102] , This property facilitates the harnessing of solar energy for driving photocatalytic reactions. Moreover, the generation of photogenerated electron-hole pairs upon photon absorption stands as another attribute necessary for their role as photocatalysts. When oxide nanoparticles intercept photons, they generate electron-hole pairs within their electronic structure. These photogenerated charge carriers play an indispensable role in instigating redox reactions during photocatalysis. The efficient separation and subsequent utilization of these charge carriers prove instrumental in achieving optimal photocatalytic activity.

[0407] Additionally, the substantial surface area inherent to oxide nanoparticles, a consequence of their diminutive dimensions and impressive surface-to-volume ratio, constitutes another salient feature. This augmented surface area offers an abundance of active sites conducive to the adsorption and reaction of target molecules, thus elevating the efficiency of photocatalytic processes. Furthermore, their chemical stability, optical resilience,and resistance to corrosion underpin their suitability for prolonged utilization in photocatalytic processes. This stability is pivotal in ensuring the sustained activity of the photocatalyst over extended periods and under fluctuating environmental conditions, including prolonged light exposure.

[0408] Furthermore, oxide nanoparticles frequently exhibit favorable redox potentials conducive to a broad spectrum of photocatalytic reactions, spanning from the oxidation of organic pollutants to the reduction of oxygen or other species. Their innate redox activity facilitates electron transfer reactions occurring at the surface of these nanoparticles.

[0409] The tunability of oxide nanoparticles stands as an additional advantageous attribute. Their properties, including size, morphology, and crystallinity, can be finely adjusted via controlled synthesis methods. This tunability empowers researchers to optimize the photocatalyst to meet the specific requirements of targeted reactions and environmental conditions.

[0410] Addressing environmental concerns, paramount consideration, many oxide nanoparticles, such as TiC>2 and ZnO, exhibit environmental friendliness and non-toxicity. This quality renders them suitable for various photocatalytic applications, especially those oriented toward environmental remediation. Additionally, certain oxide nanoparticles are economically viable and readily accessible, rendering them practical choices for large-scale photocatalytic processes

[0103] ,

[0411] Moreover, the surface of oxide nanoparticles can be chemically tailored to augment their reactivity and selectivity in specific reactions. Surface functionalization through the introduction of organic groups or metal co-catalysts offers a means to customize the photocatalyst's properties, thereby enhancing its effectiveness in targeted applications

[0104] ,

[0412] A synergy between oxide nanoparticles and aerogels is promising. Aerogels possess numerous properties conducive to the surface modification of oxide nanoparticles (see FIG. 18). These combined properties present an exciting avenue for further exploration in the realm of advanced photocatalytic materials and processes. Aerogels boast an exceptional surface area, stemming from their porous and open-cell structure. This expansive surface area offers a multitude of active sites where photocatalytic reactions can transpire. The augmented surface area fosters heightened interactions between the photocatalyst and the target pollutants, thereby augmenting the efficiency of the degradation process. In addition to their impressive surface area, aerogels exhibit low density, endowing them with lightweight characteristics. This attribute enhances their manageability and transportability, rendering them practical across a spectrum of applications. In photocatalytic reactors, the aerogels' low density facilitates effective mixing and even dispersion of the photocatalyst within the reaction solution. The porous structure of aerogels can be precisely tailored to encompass specific pore sizes and distributions. This tunability empowers control over mass transfer and diffusion rates, pivotal factors in optimizing photocatalytic reactions. A judicious engineering of pore structures ensures facile access of reactants to the active sites on the aerogel surface.

[0413] Certain types of aerogels, notably silica aerogels, exhibit remarkable transparency within both visible and ultraviolet spectral regions. This optical transparency permits the unhindered transmission of light to the photocatalyst, thereby facilitating the initiation of the photocatalytic process. Such transparency proves pivotal in ensuring that the catalyst receives a sufficient quantum of light energy to fuel the desired reactions.

[0414] Aerogels are distinguished by their chemical inertness and inherent stability. These characteristics are especially advantageous in the context of long-term utilization within photocatalytic applications, where the material must endure without undergoing degradation or undesirable reactions with the reaction solution. This stability is foundational in guaranteeing consistent performance and enduring durability.

[0415] Depending on the specific aerogel type, they can manifest exceptional thermal insulation properties. This thermal insulation attribute can play a pivotal role in sustaining a stable reaction temperature, particularly in solar-driven photocatalytic systems reliant on natural sunlight. Furthermore, it mitigates heat loss during reactions, thereby augmenting energy efficiency.

[0416] Aerogels exhibit a remarkable degree of versatility, amenable to synthesis from diverse materials, including silica, metal oxides, and carbon-based compounds. This versatility empowers researchers to select the most suitable aerogel material tailored to the requirements of specific photocatalytic applications and the nature of target pollutants.

[0417] In line with sustainability goals in environmental remediation applications, aerogels can be synthesized employing environmentally friendly solvents and processes. This environmental friendliness aligns seamlessly with the overarching objectives of promoting eco-conscious practices in addressing environmental challenges [105-107], Depictions of banana aerogels and some characteristics of them are shown in FIGS. 15A-15D. Generalized methods of making these aerogels is shown in FIG. 16. FIGS. 19A-19C show banana aerogels containing various amounts of nanoparticles (further detailed in Table 7).

[0418] Information about Lignin based on its photocatalytic application: Lignin structures are primarily composed of three main repeating units known as monolignols, which are arranged in random sequences (see FIG. 17). This results in a three-dimensional amorphous polymer with a high molecular weight. The main contributors to lignin's fundamental composition are the alcohols p-coumaryl (H), coniferyl (G), and sinapyl (S)

[0107] , Approximately 50% of the components of lignin are comprised of aromatic rings

[0108] , These monomers undergo radical coupling and cross-linking processes in a combinatorial manner, resulting in the formation of diverse lignin structures

[0109] , These units are organized in random sequences. Lignin also contains phenyl propane units, which are derived from hydroxyl- and methoxy-substituted phenylpropane units. The average molecular weight (Mw) of Kraft lignin ranges from 1 kDa to 100 kDa, with a polydispersity index (PDI, M w / M n) ranging from 1.8 to 3.6

[0110] ,

[0419] Lignin, as indicated by the provided source

[0111] , is a natural polymer, ranking second in abundance after cellulose and being one of the most prevalent natural polymers in thenatural world. It plays a significant role in forming the structural framework of plants, constituting approximately 19-35% in wood and 14-24% in herbaceous plants. Due to its favorable traits such as biodegradability, reproducibility, and environmental friendliness, it has garnered considerable global attention. Each year, pulp and paper companies employ various pulping techniques to extract around 2.6 * 107 tons of lignin from plant fiber raw materials

[0112] , Lignin molecules are rich in functional groups, including carbonyl groups, phenolic hydroxyl groups, and alcoholic hydroxyl groups, which can be utilized to synthesize a variety of functional materials

[0113] , In contemporary paper-making facilities, most of the lignin is incinerated as a fuel during the chemical recycling process

[0114] , However, direct combustion of lignin has limited calorific value and results in both biomass resource wastage and substantial environmental pollution

[0115] ,

[0420] The molecular structure of lignin and its derivatives contains various active groups, as mentioned in the provided source

[0116] , These active groups have the capacity to efficiently absorb contaminants from wastewater. Consequently, cost-effective adsorbents can be developed utilizing lignin as the primary raw material. Despite the urgent need to maximize lignin utilization, there is a dearth of literature on lignin-based adsorbents, as indicated by the source

[0117] ,Table 7. 2% Banana and nanoparticle aerogel.3. Aerogel Optimization for In-situ Chitosan Banana aerogel

[0421] Preparation of In-situ Banana Hydrogel: Prepare chitosan solution (1 or 2%) in the presence of acetic acid (2%) at a 750-850 RPM speed. Add banana fibers (knife-milled with 60 size sieve for 3 times from banana rods) to 1% chitosan solution at 1000 RPM to prepare homogenous dispersion. Heat the dispersion to 100 °C, then cool it to 70 °C. Transfer the dispersion to the homogenizer, run it for 5 minutes at low or no pressure, then increase the pressure to 700 bars. Run the homogenizer for another 20 minutes for proper defibrillation of banana fibers. Stir the dispersion continuously to avoid any blockage in the homogenizer.

[0422] Preparation of Aerogels from hydrogels: Banana hydrogels were aerated for 3 minutes using a high-speed stirrer at 20,000 rpm to create a stable foam. The structures were frozen at -20°C for at least 6 hours. Following this, they were freeze-dried at -40°C and 1 mbar pressure until completely dry, which took 7-11 hours, depending on the sample size. This process was carried out using the LABCONCO freeze-drying system.

[0423] Heat treatments of aerogels: Heat the prepared aerogels at temperatures 150, 170 and 190°C for 10 minutes at 700 rpm airflow. It was observed that adding chitosan improved aerogel stability in oil and water. Further, the heat treatment of aerogels provided more integrity to the shape and size in oil and water. Chitosan acts as a cellulose crosslinking agent and retains its shape after absorbing water and oil. In general, initial observations showed that the heat treatment of in situ chitosan aerogels showed more stability to the shape and size. The qualitative test of selective removal of oil from oil and water mixture and the stability in water was performed for banana fiber aerogel, 1% in-situ chitosan banana aerogel, and heat treated at 150°C 1 % in-situ banana aerogel (as shown in FIGS. 20A-20R) to study the effect of the presence of chitosan and heat-treatment in the aerogel. Banana fiber aerogels with or no chitosan and heat treatment inherently showed good absorbency of both oil and water. But it loses its shape in a few minutes with some force applied. It can also be seen in the images that aerogel with no chitosan cannot retain the oil (FIG. 20F) and water (FIG. 20C) after removing from the oil and water mixture and water, respectively. In contrast, the in-situ chitosan banana aerogel maintains its shape in the water; and retains oil and water (FIGS. 20I, 20L, 200, and 20R) after it is removed. Moreover, the banana fiber aerogel absorbed the surface water and got completely wet within 6 seconds. In contrast, the in-situ chitosan banana aerogel and heat-treated in-situ banana aerogel got completely wet in 48 and 60 seconds, respectively, displaying their hydrophobicity increased significantly. It is important to note that all three aerogels remain floating at the top after absorbing water. In-situ chitosan banana aerogels (with or without heat treatment) bounced back to the top and floated even after some force was applied.

[0424] In-situ chitosan with the heat treatment shows promising results with increasing the hydrophobicity of the aerogel. Instead of using its conventional synthetic alternatives to make aerogel hydrophobic, biobased and sustainable chitosan could be the better choice in the long run. FIGS. 21A-21 F show details of a chitosan / banana hybrid aerogel.

[0425] Banana aerogel encased in a thin layer of polyolefins. Polypropylene has a water- repellent quality and can resist water damage, which could form a shield on the aerogel's surface, stopping water uptake and increasing its durability in moist conditions. This modification may be useful for applications where keeping the aerogel's shape and function in wet settings is important. Applying a thin polypropylene layer on an aerogel will potentially improve its water-repellency of the aerogel wrapped in the thin film of the polypropylene (FIG. 22). This idea is tested with thin polypropylene films, and the next study aims to try eco- friendlier and more feasible polylactic acid (PLA) thin non-woven films. This trial will eliminate the need for further modification of the aerogel in terms of making aerogel more water- repellent which in turn reduces the capacity of the aerogel for oil uptake and make aerogel more costly.

[0426] Algae-based aerogel. Cellulose sheet was knife milled (Wiley Mini Mill) using a sieve size of 60 three times through. The grinded cellulose powder was stored inside a convectionoven at 60°C. Next, slurries were made from knife-milled powders to make a 2% weight / volume pulp hydrogel. These gels consisted of 10 grams of dry weight with a constant amount of carboxymethyl cellulose (CMC). 500 ml of water were used to prepare the slurry, and 1.25g of CMC was added as a dispersant to the powder. After the CMC dissolved, a predetermined amount of milled powder was added to the hot CMC solution. The slurry was mixed with a stirring at 700 rpm until the powder was completely dispersed. The mixing continued until the temperature reached 100°C, and then the slurry was left to cool to 70°C. At this point, the slurry was poured into the homogenizer and was homogenized for 20 mins. After homogenization slurry was mixed in different ratios with wet weight of the selected algae from 2 ml to 8 ml with 2 % pulp hydrogel (FIG. 23).

[0427] Oil Absorption and Retention. Oil absorption and retention capacities over a 24 hour period were tested for each sample of algae-based cellulose aerogel. 2C8P was shown to have better oil sorption capacity (see FIG. 24A). 2C8P and 4C6P were shown to have better oil retention ability (see FIG. 24B)

[0428] Thermal Gravimetric Analysis (TGA). The Thermogravimetric Analysis (TGA) method is often used to measure the mass change of materials over different temperature and time intervals, under controlled atmospheric conditions. In this specific study, TGA curves were produced for each sample of algae-based cellulose aerogel to see how the mass changed as the temperature rose (see FIG. 25). These curves showed that the addition of algae had a significant effect on the mass change of the aerogel samples when compared to cellulose aerogel. The onset temperature of decomposition, a critical point where mass loss quickly increases with temperature, was lower in all algae-based aerogel samples. For the algae aerogel, the main mass loss happened between 250-350°C. On the other hand, cellulose aerogel usually goes through a two-step thermos-oxidation process, leading to the formation of aliphatic char and flammable volatiles, followed by further oxidation and breakdown of char, which normally happens at a temperature range of 300-400°C.

[0429] Freezing temperature and time optimization. Three different containers, namely polystyrene, aluminum, and glass, were chosen for further optimization of the freezing temperature and duration required to transform a hydrogel into an aerogel (see FIGS. 26A- 26C). These materials were selected due to their thermal conductivity, as indicated by the following order: aluminum > glass > polystyrene. Four distinct temperatures, -10°C, -15°C, - 20°C, and -80°C, were chosen for optimization at various time intervals, volumes, and thicknesses to facilitate the creation of the aerogel.Table 8. Characteristics measures of initial hydrogel freezing at -10°C while varying the volume and thickness of the material.

[0430] A negative sign and legend numbers 1-3 at the freezing level signify a temperature above the freezing point, indicating that the material remains in a liquid state. The presence of multiple negative signs suggests a more disordered system.

[0431] Conversely, a positive sign and legend numbers 4-6 represent the onset of freezing due to a drop in the system’s temperature. Multiple positive signs indicate that the material has solidified, and the system’s molecules exhibit greater order upon solidification into ice.Table 9. Characteristics measures of initial hydrogel freezing at -15°C while varying the volume and thickness of the material.Table 10. Characteristics measures of initial hydrogel freezing at -20°C while varying the volume and thickness of the material.Table 11. Characteristics measures of initial hydrogel freezing at -80°C while varying the volume and thickness of the material.

[0432] The experiment found that the polystyrene plates were the worst at conducting heat among all the containers, which made them freeze slower. Glass, however, has heat conductivity that is 1000 times better than polystyrene but its smaller volume made this difference not very big. Aluminum, as a metal, conducted heat the best by freezing the hydrogel quicker than other containers at all the chosen temperatures. Pore size distributions of aerogels produced using the various containers is presented in FIG. 27.

[0433] Conclusion: Freezing hydrogel using aluminum containers demonstrates superior efficiency compared to other materials. Specifically, the aluminum container is capable of freezing hydrogel in a mere 15 minutes at -80 °C, and within 30 minutes at temperatures of -10 °C, -15 °C, and -20 °C. In contrast, a polystyrene container requires approximately 30 minutes to freeze hydrogel at -80 °C, and a significantly longer duration of 3 hours at temperatures of -10°C, -15°C, and -20°C. Similarly, a glass container necessitates 20 minutes at -80 °C and 2 hours at -10°C, -15°C, and -20°C to achieve the same result. This provides an improvement in the efficiency of hydrogel freezing processes, particularly when utilizing aluminum containers.

[0434] Preparation of initial aerogel samples for pore analysis: Aerogels of banana (1.wt%) and silk (1.wt%) in 1 % chitosan solution were aerated for 3 min using high-speed stirrer at 20,000 rpm. Once a stable foam dispersion was prepared, it was transferred into aluminum, glass, and polystyrene containers. The containers were then frozen at -80°C for a minimum of 15 - 30 minutes, as per Tables 8-11. Following this, the samples were freeze-dried at -40°C and 1 mbar pressure until completely dry. This process took between 9-11 hours, depending on the sample size, and was carried out using the LABCONCO freeze drying system, FREEZONE.

[0435] Pore size and filter flow efficiencies of the initial NC aerogels: Were analyzed using porometer, PMI, l-Pore.

[0436] Conclusion: Aerogel is frozen in aluminum containers, exhibits a higher density of pore distribution that spans from 250 microns to 2220 microns. In contrast, freezing aerogel in glass containers leads to a wider range of pore sizes that span from 500 microns to 7034 microns. Frozen in a polystyrene container, aerogel exhibits a narrow range of pore size between 425 microns and 1212 microns, which is lower than the density of pores found in aluminum and glass containers.4. In Situ Chitosan-Nanocellulose / Wool Composite Aerogel

[0437] The global aerogel market in 2024 was valued at USD 0.9 billion, projected to increase to USD 1.6 billion by 2029, with a compound annual growth rate (CAGR) of 12.8%

[0117] , The application of aerogel is expanding rapidly in various fields, including building insulation, aerospace, oil and water separation, chemical engineering, life sciences, textiles, transportation, electronics, and more [118,119], In the current era, thermal insulation materials are a need for energy conservation and thermal management as well as an energy-efficientmaterial [119,120], Commercial aerogels for thermal applications are mostly confined to silica aerogels. Additionally, these commercial aerogels are primarily used in non-personal applications, such as thermal insulation for pipelines or as a thermal insulation material for buildings to conserve energy

[0119] , The common aerogel used as a thermal insulation material is sourced from synthetic or fossil fuel-based materials that are neither renewable, biodegradable, eco-friendly, nor sustainable

[0120] , Thus, lightweight, multi-functional, eco- friendly, and high-performance sustainable aerogels are needed for applications in various fields, including textiles and clothing.

[0438] Nanocellulose (NC) is renewable, biodegradable, abundant in nature, and can be extracted from plant and microbial sources. The inherent properties of natural sources can also impart comparable properties to synthetic aerogels without compromising its mechanical or physical structure. For instance, silica aerogels are widely researched, including by the National Aeronautics and Space Administration, for their potential space launch applications due to their outstanding multiple properties, such as high thermal insulation

[0121] , The key problem with silica aerogels is that they are significantly brittle

[0121] , On the other hand, NC aerogels exhibit higher thermal insulation along with enhanced mechanical integrity. It is interesting to note that the thermal conductivity of nanofibrillated cellulose (NFC) aerogel can be as low as 18 mW m-1K"1, which is very much comparable with silica aerogels' thermal conductivity range of 12-15 mW m-1K"1and lower than the thermal conductivity of air, which is 25 mW m-1K"1at room temperature

[0122] , That means, in addition to the sustainability and eco-friendly aspects of NCs, they also exhibit good thermal insulation, high tensile strength, a large surface area, and compatibility for making composites with other materials

[0118] ,

[0439] Given the above circumstances, thermal insulation is desired for various applications, including building insulation, aerospace applications, protective and winter textiles, and more. Based on this, NC derived from wood pulp with wool fibers is combined to develop aerogel, utilizing the wool’s unique properties, such as lower thermal conductivity, elasticity, and resiliency. The interaction between wool and NC is relatively unexplored. Chitosan was selected as a cross-linking agent in developing an aerogel coating that serves as both an antimicrobial agent and a defense against potential bacterial infections in the long term for protein wool fiber. The composite aerogel's physical, mechanical, and thermal properties are evaluated, including its thermal conductivity measured using a hot-guarded sweat plate under both dry and wet conditions.

[0440] Materials: Cellulose micro powder (from wood pulp, BWW40 from ARBOCEL), Wool fiber (from Corriedale sheep, Revolution Fibers), Chitosan (from shrimp cells, Sigma-Aldrich), 100% cotton woven fabrics (400 GSM), Acetic acid (from EMD chemicals), and Deionized water

[0441] Aerogel Synthesis Process - Control aerogel: A 0.5 wt% chitosan solution was prepared by mixing it with 2 wt% acetic acid and continuously stirring until it dissolved completely (more than 6 hours). Afterward, a 2 wt% in situ chitosan cellulose slurry wasprepared by adding the required amount of cellulose micro powder to a 0.5 wt% chitosan solution, stirring continuously, and heating it to 90°C. After cooling to 70°C, the solution was poured into the feeder of the high-pressure homogenizer and homogenized at around 700 PSI for 60 minutes (for a 500 g solution). The high-pressure homogenizer defibrillates the cellulose micro powder, forms NFC, and prepares the 2 wt% NFC in situ 0.5 wt% chitosan hydrogel. This hydrogel was stored in a standard refrigerator at approximately 4°C for 6 hours to cool down. After that, they were poured into a 63.5 mm x 63.5 mm x 5 mm aluminum mold. These molds were transferred to the ultra-low temperature freezer at -80°C for 6 hours and then freeze-dried at -84°C and 1 mbar pressure until completely dry (at least 12 hours) using the LABCONCO freeze drying system, FREEZONE 4.5. Removed freeze-dried samples were hot air-dried for 5 minutes at 120°C before using for characterization.

[0442] Aerogel Synthesis Process - Test sample: Wool fiber was added in different quantities to develop the test sample. The wool fiber was first converted into microfiber by feeding it into a knife mill and then sieving it through a 250-micron mesh. The wool microfiber was added to the NFC / chitosan dispersion before high-pressure homogenization, as outlined in Table 12. Afterward, the same procedure (freezing and freeze-drying) was followed as described above. The schematic methodology is shown in FIG. 28.Table 12. Sample plan for the in situ chitosan-NFC / Wool composite aerogel.

[0443] Physical Characterization - Density: The density (p, g / cm3) of the developed NC / wool aerogel can be obtained by dividing the mass by the NC / wool aerogel volume.

[0444] Porosity: The bulk density (g / cm3) of the mixture of the constituents of the NC / wool aerogels: NC, raw wool fiber, and chitosan can be obtained by following Equation 3 [123,124]:

[0445] Here, CNC, Cwooi, and Cchitosan represent the percentage (%) content in the aerogel sample, respectively, pNc, Pwooi, and pChitosan are the densities (g / cm3) of the NC, wool fiber, and chitosan, respectively. Afterward, the porosity (<t>) has been calculated as

[0123] :

[0446] Mechanical Characterization - Compression test: The compression test was performed on a 20 mm x 20 mm x 4 mm aerogel sample using an Instron 3343 UniversalTesting Machine with a crosshead speed of 1 mm / min. The stress-strain curve was recorded up to 80% strain with a constant load of 50 N.

[0447] Thermal Characterization - Thermal conductivity: Following the ASTM F1868 method, the dry thermal conductivity of 63.5 mm x 63.5 mm x 5 mm aerogel samples was measured using a Thermetrics sweating guarded hotplate.

[0448] Thermogravimetric analysis (TGA): To assess the thermal stability of the aerogels, TGA was conducted using samples of 2 mg from 30°C to 800°C at a 20°C / min temperature gradient under nitrogen gas using a TGA instrument from PerkinElmer, TGA / DTGA 851.

[0449] Results and Observations: As discussed above, four aerogels with different wool fiber contents were prepared. FIGS. 29A-D shows the different developed in situ chitosan- NFC / wool composite aerogels.

[0450] Table 13 demonstrates the sample details and their physical properties, including the density and porosity of the aerogels with varying compositions of chitosan, NFC, and wool fiber. All samples exhibit extremely low densities (ranging from 0.025 to 0.028 g / cm3) and high porosity levels (around 98%), indicating their lightweight and highly porous nature. The sample with 0.5 wt% chitosan and 2 wt% NFC exhibited the highest density (0.028 g / cm3) and porosity of 98.05% due to the higher NFC content providing a more robust structural framework. As the NFC content decreased and wool content increased, a slight decrease in density and a negligible change in porosity were observed. Notably, the sample with 0.5 wt% NFC and 1.5 wt% wool had the lowest density (0.025 g / cm3) but maintained a high porosity of 98.03%. Overall, these results confirm that the developed aerogels are ultra-light and highly porous, with only minor variations based on composition. All the developed in situ chitosan-NFC / wool aerogels had low density and high porosity, which aligns with the physical properties reported in the existing literature, such as low density (0.0011 to ~0.5 g cm-3) and high porosity (>90%)

[0125] ,Table 13. Physical properties of the in situ chitosan-NFC / wool composite aerogels .

[0451] Compressive Properties: The compression properties of the developed aerogels were evaluated to assess their mechanical performance under load, as shown in both the stressstrain curves and the summary in Table 14. Four different formulations were tested, all containing a fixed amount of 0.5 wt% chitosan while varying the concentrations of NFC and wool fibers. Among all samples, the one with 0.5 wt% chitosan and 2 wt% NFC exhibited the highest compression modulus (399.35 kPa) and compressive strength (95.44 kPa), confirming its superior stiffness and load-bearing capacity. As the NFC content decreased and wool content increased, both the modulus and compression stress values reduced steadily. The lowest mechanical performance was observed in the sample with 0.5 wt% NFC and 1.5 wt%wool, showing a compression modulus of 113.72 kPa and stress of 64.85 kPa. These trends are also reflected in the stress-strain behavior (FIG. 30). The 2 wt% NFC sample exhibited the steepest slope and highest stress values throughout the strain range, whereas the curves for the wool-reinforced samples shifted downward with increasing wool content. The results demonstrate that NFC acts as the primary reinforcing agent, enhancing the aerogel's mechanical rigidity, while wool contributes more to structural flexibility and reduces compressive strength. This tunability enables the tailoring of the aerogel’s mechanical properties to meet specific application requirements, such as insulation or cushioning.Table 14. Compressive properties of the in situ chitosan-NFC / wool composite aerogels

[0452] Thermogravimetric analysis (TGA): FIG. 31 shows that all samples exhibit a two-step degradation pattern, with an initial weight loss below 150°C due to moisture evaporation, followed by major decomposition in the range of 250-400°C, corresponding to the breakdown of organic components.

[0453] The sample containing 0.5 wt% chitosan and 2 wt% NFC exhibited the highest thermal stability, with a degradation onset at approximately 280°C and a major decomposition peak at around 340°C. It also showed the highest char residue (-22%) at 800°C, indicating excellent thermal resistance and a strong ability to form char. As the wool content increased and NFC content decreased, the degradation temperatures shifted gradually to lower values. The 0.5 wt% chitosan / 1.5 wt% NFC / 0.5 wt% wool and 0.5 wt% chitosan / 1 wt% NFC / 1 wt% wool samples exhibited degradation onsets at approximately 270°C and 265°C, respectively, with peak degradation occurring near 330°C and 325°C, respectively. The sample with the highest wool content (1.5 wt%) and the lowest NFC (0.5 wt%) exhibited the lowest thermal stability, with degradation starting at 255°C and peaking around 315°C, accompanied by the lowest char residue (-14%).

[0454] These results demonstrate that NFC contributes significantly to the thermal resistance and stability of the aerogels, while wool enhances flexibility but slightly compromises thermal integrity. By adjusting the chitosan-NFC-wool ratios, the thermal behavior of the aerogels can be finely tuned, allowing for the design of bio-based insulation materials suitable for various applications.

[0455] Thermal Resistance Observation: The thermal resistance performance of the in situ chitosan-NFC / wool aerogel was evaluated using a sweating-guarded hot plate, as per ASTMF1868-23. As shown in FIG. 32, the graph demonstrates the superior insulating capability of the aerogel compared to conventional cotton fabric. The thermal resistance of the cotton fabric remained consistently below 1 °C m2 / W throughout the testing period. In contrast, all four developed composite aerogels exhibited a significantly higher peak thermal resistance, which is beyond the measurement capability of the sweating-guarded hot plate. This high and sustained thermal resistance confirms the aerogel's excellent ability to hinder heat transfer. These results validate the aerogel’s suitability for textiles and protective clothing applications, offering enhanced insulation while maintaining breathability and comfort.

[0456] The in situ chitosan-NFC / wool aerogels discussed in this Example exhibited density and porosity values that are comparable to those reported in the current literature for high- performance bio-based aerogels. Despite their ultralight nature and high porosity — favorable traits for thermal insulation materials — these aerogels maintained structural integrity and uniform surface, confirming the effectiveness of the formulation strategy. Notably, as the wool content increased in the aerogel matrix, the material demonstrated enhanced flexibility and reduced compression modulus. This reduction in stiffness, coupled with improved compressibility, suggests that wool incorporation contributes to enhanced mechanical adaptability, which is crucial for applications requiring conformability and softness, such as wearable textiles. Thermal resistance measurements conducted using the sweating-guarded hot plate, as specified in ASTM F1868-23, revealed the aerogel's excellent ability to hinder heat transfer. The aerogel significantly outperformed conventional cotton fabric in terms of thermal resistance, exhibiting sustained values that support its suitability for thermal protective applications. This demonstrates that the in situ chitosan-NFC / wool aerogel is structurally and mechanically compatible with textile integration, exhibiting superior insulating performance functionally. Overall, the combination of lightweight structure, tunable compressibility, and outstanding thermal insulation positions this bio-based aerogel as a promising material for sustainable and high-performance applications, including textiles and clothing.5. In Situ Chitosan-Nanocellulose / Glycerol Aerogels

[0457] Nanocellulose (NC) is engineered, nano-structured cellulose derived from plants like cotton and wood. Depending on the production method and overall size, it can be categorized as nanofibrillated cellulose (NFC), nanocrystalline cellulose, or bacterial cellulose

[0118] , NC has high water absorbency, large surface area, and low environmental impact resulting from its abundant surface hydroxyl groups

[0118] , NFC-based aerogels and foams can replace the absorbent layer of conventional pads without compromising performance. These materials are entirely free from synthetic polymers, such as superabsorbent polymers (SAPs), while retaining superior superabsorbent properties. The necessity of disposable pads is undeniable, as they have become widely popular and an essential product for children, women, and elderly individuals. Discussed in this Example is an in situ chitosan-NFC / glycerol aerogel developed through green processing methods, demonstrating comparable performance to currentcommercial absorbent pads available on the market in terms of liquid absorbency and flexibility. This in situ chitosan-NFC / glycerol outlines a promising approach to developing a sustainable superabsorbent pad that meets the needs of environmentally conscious consumers. By leveraging the unique properties of NFC, glycerol, and chitosan, this material can contribute to sustainability and biodegradability in the personal care market.

[0458] Materials: Cellulose micro powder (from wood pulp, BWW40 from ARBOCEL), Glycerol (from J.T. Baker), Chitosan (from shrimp cells, Sigma-Aldrich), Acetic acid (from EMD chemicals), and Deionized water

[0459] Aerogel Synthesis Process: A 0.5 wt% chitosan solution was prepared by mixing it with 2 wt% acetic acid and continuously stirring until it dissolved completely (more than 6 hours). Afterward, a 1 wt% in situ chitosan cellulose slurry was prepared by adding the required amount of cellulose micro powder to a 0.5 wt% chitosan solution, stirring continuously, and heating it to 90°C. After that, the required glycerol was added to the dispersion, which was constantly stirred according to the sample plan (Table 15). After cooling to 70°C, the solution was poured into the feeder of the APV1000 high-pressure homogenizer and homogenized at around 700 PSI for 60 minutes (for a 500 g solution). The high-pressure homogenizer defibrillates the cellulose micro powder, forms NFC, and prepares 1 wt% NFC in situ as a 0.5 wt% chitosan hydrogel with or without glycerol. This hydrogel was stored in a standard refrigerator at approximately 4°C for 6 hours to cool down. After that, they were poured into an aluminum mold measuring 63.5 mm x 63.5 mm x 5 mm. These molds were transferred to the ultra-low temperature freezer at -80°C for 6 hours and then freeze-dried at -84°C and 1 mbar pressure until completely dry (at least 12 hours) using the LABCONCO freeze drying system, FREEZONE 4.5. Removed freeze-dried samples were hot air-dried for 5 minutes at 120°C before using for characterization.Table 15.: Sample plan for the in situ chitosan-NFC / glycerol aerogel

[0460] Absorbency Characterization Techniques: Absorbent Capacity Test: To determine the absorbent capacity of the aerogel, approximately 100 mg of dried aerogel was used for each test. The sample was first immersed in 40 mL of deionized (DI) water at room temperature (~25 °C) and kept submerged for 60 seconds to allow complete wetting and absorption. Following immersion, the sample was carefully transferred onto a dry napkin and held for 5 seconds to remove surface water without applying any external pressure. Subsequently, the aerogel was placed on a metal mesh for an additional 60 seconds to allow gravitationaldrainage of loosely held water. After the drainage period, the final weight of the wet aerogel was recorded. The absorbent capacity was calculated using Equation 5:Absorbent Capacity (g) = Vwet- V / dryEq. 5

[0461] In this equation, l / l / dry= Initial dry weight of the aerogel (approx. 100 mg) and l / l / wet = Final weight after absorption and drainage. This method accurately assesses the waterholding capacity of the aerogel under conditions simulating real-world absorbent use. The schematic methodology is shown in FIG. 33.

[0462] Observation: For utilizing in situ chitosan-NFC / glycerol aerogel as the absorbent layer in pad applications, achieving adequate flexibility is essential to ensure wearer comfort and conformability during use. FIGS. 34A-34C illustrate the physical appearance and mechanical flexibility of the developed in situ chitosan-NFC / glycerol-based aerogel. FIG. 34A shows the top view of the aerogel, exhibiting a uniform, smooth, and crack-free surface with well-defined edges. The monolithic form indicates successful in situ gelation and drying without structural collapse or surface deformation. FIG. 34B displays the side profile under compression. The aerogel maintains its structural integrity without visible cracking or permanent deformation, demonstrating moderate resilience under applied force. FIG. 34C presents the aerogel under bending stress. The sample demonstrates significant flexibility, bending smoothly without fracturing or delaminating, even under manual handling. This behavior confirms the elastic nature of the aerogel, attributed to the interpenetrating polymer network formed by chitosan and NFC, where glycerol contributes to flexibility, which provides both mechanical strength and bendability. This combination of structural uniformity, bendability, and compressibility is crucial for practical applications in wearable textiles, hygiene products, and flexible absorbent devices, distinguishing this formulation from conventional brittle aerogels.

[0463] The absorbent capacity of the developed in situ chitosan-NFC / glycerol aerogels was found to be comparable to that of commercial disposable pad absorbent layers. For comparison, the DI water absorbent capacity of two commercially available disposable pads was also evaluated under identical testing conditions described above. One of the commercial pads is a baby diaper denoted as COM-1 , and another is an adult incontinence pad denoted as COM-2. Table 16 presents the DI water absorbent performance of the in situ developed chitosan-NFC / glycerol aerogels, which was evaluated and compared with two commercial disposable pad absorbent layers (COM-1 and COM-2). Among all samples, the aerogel composed of 0.5 wt% chitosan and 1 wt% NFC without glycerol exhibited the highest absorbency, retaining 6.28 g of water, equivalent to 62.79 times its dry weight. This exceptional absorbency is attributed to the highly porous and hydrophilic network structure formed between chitosan and NFC. However, despite its outstanding absorbent capacity, this formulation was relatively rigid. It lacked sufficient flexibility, limiting its suitability for use in applications such as sanitary pads or wearable absorbent products, where comfort and conformability are essential. To address this limitation, glycerol was incorporated as aplasticizer at various concentrations to improve flexibility. Notably, the addition of 0.1 wt% and 0.25 wt% glycerol maintained high absorbent capacities of 5.73 g (57.32 times of dry mass) and 5.98 g (59.75 times of dry mass), respectively, while significantly enhancing the softness and flexibility of the aerogels. Both of these formulations outperformed the commercial absorbent layers, with COM-1 and COM-2 exhibiting lower absorbencies of 1.53 g (15.32 times the dry mass) and 5.16 g (51.64 times the dry mass), respectively. This indicates that the optimized glycerol-containing aerogels not only offer mechanical advantages but also superior fluid retention compared to conventional alternatives. However, higher glycerol contents (0.75 wt% and 1 wt%) further improved flexibility. Still, they resulted in a marked decrease in absorbency, suggesting that excessive plasticizer content may interfere with the aerogel’s internal pore structure or its ability to bind water.Table 16. DI Water Absorbent Capacity of in situ chitosan-NFC / glycerol aerogels and commercial pads.

[0464] Overall, these results demonstrate that the in situ chitosan-NFC / glycerol aerogels, particularly those containing 0.1-0.25 wt% glycerol, strike an effective balance between absorbent capacity and flexibility. This makes them candidates for eco-friendly, high- performance absorbent applications, providing advantages over current commercial disposable pad materials.6. In Situ Chitosan-Nanocellulose / Phytic Acid Aerogels

[0465] Nanocellulose is a sustainable and eco-friendly material well-suited for aerogel development due to its outstanding properties. Its nanoscale fibrous structure, rich in hydroxyl groups, enables strong intermolecular interactions and efficient crosslinking with other compounds, allowing for the formation of multifunctional aerogel networks

[0118] , However, nanocellulose is inherently flammable, which can limit its use in applications that require flame resistance. For example, flame-retardant textiles demand both thermal insulation and flame retardancy. Although nanocellulose-based aerogels exhibit excellent thermal insulation, they are not unsuitable for flame-retardant clothing due to their high flammability.

[0466] To overcome this limitation, various flame-retardant additives can be incorporated into the nanocellulose aerogel matrix. In this Example, phytic acid — a naturally derived, plantbased compound rich in phosphate groups

[0126] — was integrated into an in situ chitosannanocellulose aerogel using a one-pot synthesis method. Phytic acid is abundant in nature and is recognized for its flame-retardant potential due to its phosphorus content

[0126] , By combining nanocellulose sourced from wood pulp with phytic acid and using chitosan as a crosslinking agent, a composite aerogel was developed that leverages the flame-retardant properties of phytic acid. The resulting aerogel demonstrated enhanced flame resistance while maintaining good mechanical integrity, making it a promising candidate for flame-retardant and thermally insulating applications.

[0467] Materials: Cellulose micro powder (from wood pulp, BWW40 from ARBOCEL), phytic acid solution (50% (w / w) in H20, from Sigma-Aldrich), Chitosan (from shrimp cells, Sigma- Aldrich), Acetic acid (from EMD chemicals), and Deionized water

[0468] Methods - In Situ Preparation of Chitosan-Phytic Acid Dispersion: A 0.5 wt% chitosan solution was prepared by mixing it with 2 wt% acetic acid and continuously stirring until it dissolved completely (more than 6 hours). To evaluate the interaction behavior between chitosan and phytic acid, a series of aqueous solutions were prepared by varying the molar ratios of chitosan to phytic acid while maintaining a constant chitosan concentration of 0.5 wt%. The tested ratios included 1 :1 , 2:1 , 3:1 , 4:1 , 6:1 , 8:1 , and 10:1 (chitosan: phytic acid). The solutions were stirred for several hours to ensure homogeneity, followed by a resting period of at least 30 minutes to assess dispersion stability and compatibility.

[0469] Aerogel Synthesis Process: After preparing the chitosan-phytic acid dispersion, 1 wt% cellulose micro powder was added to the specific chitosan-phytic acid dispersion, which was stirred continuously and heated to 90°C. After cooling to 70°C, the solution was poured into the feeder of the high-pressure homogenizer and homogenized at around 700 PSI for 60 minutes (for a 500 g solution). The high-pressure homogenizer defibrillates the cellulose micro powder, forms nanofibrillated cellulose (NFC), and prepares the 1 wt% NFC in situ chitosan / phytic acid hydrogel. This hydrogel was stored in a standard refrigerator at approximately 4°C for 6 hours to cool down. After that, they were poured into an aluminum mold measuring 63.5 mm x 63.5 mm x 5 mm. These molds were transferred to the ultra-low temperature freezer at -80°C for 6 hours and then freeze-dried at -84°C and 1 mbar pressure until completely dry (at least 12 hours) using the LABCONCO freeze drying system, FREEZONE 4.5. Removed freeze-dried samples were hot air-dried for 5 minutes at 120°C before using for characterization.

[0470] Characterization: Flame Retardancy Test: The aerogel samples were positioned vertically above a gas flame to evaluate their flammability. Each sample was exposed directly to the flame for up to 60 seconds or until ignition occurred. Upon ignition, the samples were immediately removed from the flame, and their burning behavior was observed to assess flame propagation, self-extinguishing characteristics, and overall flame retardancy.

[0471] Observation: As shown in the visual assessment (FIGS. 35A and 35B), immediate precipitation or phase separation was observed in the 1 :1 and 2:1 chitosan: phytic acid ratios. These samples displayed a clear supernatant after the resting period, indicating rapid complexation and aggregation due to charge neutralization and ionic crosslinking between the highly protonated chitosan chains and the multiple anionic phosphate groups of phytic acid. This suggests that at lower chitosan: phytic acid ratios, strong ionic interactions lead to flocculation or gel-like precipitation.

[0472] In contrast, solutions with higher chitosan: phytic acid ratios (3:1 to 10:1) exhibited stable dispersions, with no visible precipitation even after prolonged rest. These samples retained a cloudy or colloidal appearance, suggesting incomplete complexation and stable dispersion of the components in aqueous medium. This behavior is favorable for the uniform integration of phytic acid within the chitosan matrix during downstream processing, such as the fabrication of aerogels. These results demonstrate that the molar ratio between chitosan and phytic acid critically governs the solubility, dispersion behavior, and potential for homogeneous crosslinking. The higher ratios (>3:1) are particularly suitable for forming stable precursor solutions, which are essential for in situ aerogel fabrication. Uniform dispersion and controlled crosslinking are critical for achieving desirable mechanical and flame-retardant properties.

[0473] Flame retardancy properties: The flammability performance of two aerogel formulations — in situ 0.5 wt% chitosan 1 1 wt% NFC and in situ 0.5 wt% chitosan 1 1 wt% NFC / 0.125 wt% phytic acid — was evaluated by direct flame exposure (FIGS. 36A and 36B). The visual sequence illustrates distinct differences in flame retardant behavior between the unmodified and phytic acid-modified aerogels.

[0474] For the unmodified in situ chitosan / NFC aerogel, immediate ignition occurred within 1 second of flame application, followed by rapid combustion and continuous burning. By 10 seconds, the sample was entirely consumed by the flame, leaving behind only a fragile charred residue. This indicates high flammability and poor flame resistance, which limits its standalone applicability in flame-retardant applications without further modification. In contrast, the phytic acid-modified aerogel exhibited significantly improved flame retardancy. No ignition was observed even after 1 , 5, and 10 seconds of continuous flame exposure. Instead of burning, a localized char layer gradually formed on the surface, indicating the material's ability to decompose into a protective carbonaceous barrier thermally. At 60 seconds, only slight ignition was observed at the pre-charred area, with no flame propagation. The final residue maintained its structural integrity with only surface charring, demonstrating effective flame inhibition.

[0475] This comparative analysis demonstrates that incorporating phytic acid, a bio-based, phosphorus-rich flame retardant, significantly enhances the flame resistance of the aerogel. The formation of an insulating char layer, suppression of flame spread, and preservation ofstructural integrity validate the effectiveness of phytic acid in enabling intrinsically flameretardant, eco-friendly aerogels for advanced flame-retardant applications.7. Cellulose Nanofibril Aerogels for Oil Absorption and Flame Retardancy

[0476] Oil and gas mining workers require specialized personal protective equipment (PPE) because of the hazardous work environment (see FIG. 37). Major PPE types used in oil and gas industries include flame-resistant clothing, hard hats, safety glasses, face shields, respirators, hearing protection, gloves, safety boots, high-visibility vests, chemical-resistant suits, and safety harnesses. Providing workers a coverall to protect against flash fires, an essential to guard against falling objects to prevent impact hazards, protection for eyes and face from projectile and chemical splashes, protection from burns, cuts, slipping, and visibility in low light areas are necessary tools and object in the modern world to work - prioritizing life first [127-129],

[0477] The protective gear worn by workers in the oil and gas industry has undergone significant changes over the past few decades due to increased emphasis on safety and stricter regulations. The first commercial oil well was drilled in 1859, and soon after, the first refinery began processing crude oil into kerosene. The advancement of complex processes has necessitated the implementation of health and safety management procedures and secure work practices. The oil and gas industry has evolved in response to consumer demand for improved and efficient products. The development of the internal combustion engine led to the production of gasoline and diesel fuels, while the evolution of airplanes created a demand for high-octane aviation gasoline and, subsequently, jet fuel, highlighting the critical role of the oil and gas industry in the fuel supply chain. The concept of occupational health, as defined by the International Labour Organization (ILO) and the World Health Organization (WHO), involves promoting and maintaining the optimal physical, mental, and social well-being of workers across all job types. This definition was first established in 1950 and updated in 1995 [130,131],

[0478] Oil and gas workers rely on various materials for their PPE to ensure their safety in the workplace. Flame-resistant (FR) materials such as Nomex®, Kevlar®, and PyroGuard FR® are crucial for providing protection against fire and heat. These materials are designed to withstand high temperatures and minimize the risk of burns in potentially hazardous environments. In addition to flame-resistant materials, chemical-resistant materials play a vital role in safeguarding workers against exposure to a wide range of chemicals. Tychem® and nitrile are commonly used to create protective clothing that acts as a barrier against hazardous substances, thus minimizing the risk of skin contact and potential harm. Moreover, high- visibility clothing with reflective tape and bright fabrics is essential to ensure workers remain visible, particularly in low-light conditions. This is critical for preventing accidents and enhancing overall safety in environments where visibility may be limited. Cut-resistant gloves, constructed from materials such as Kevlar® and Dyneema®, are another crucial componentof PPE for oil and gas workers. These gloves are designed to provide protection against cuts and lacerations, which are common risks in industrial settings. Finally, insulated materials are utilized to keep workers warm and comfortable in cold environments, providing protection and comfort during long work hours in challenging conditions [132,133],

[0479] Chitosan, which is derived from chitin found in crustacean exoskeletons, has demonstrated promise as a flame retardant when combined with other compounds. This material can be utilized in layer-by-layer assemblies to create flame retardant coatings on fabrics. Additionally, phytic acid, either alone or in combination with chitosan, has been researched for flame retardant treatment of wool fabric [133-135],

[0480] Moreover, polysaccharides obtained from brown algae have displayed potential for enhancing flame retardancy when combined with other materials. Furthermore, various proteins, including milk and soy proteins, have been explored for their flame retardant properties when utilized with additives or coatings. Among these biomaterials, cellulose stands out as a cost-effective and abundant option that is derived from natural sources such as cotton and wood pulp. Its versatility makes it a promising choice for PPE due to its softness, comfort, high absorbency, breathability, biodegradability, and amenability to various treatments and textile applications.

[0481] Cellulose fibers can be made fire-resistant by treating them with flame retardants. There are different types of compounds and treatments that have been researched to enhance the flame retardancy of cellulose-based textiles. Phosphorus-based flame retardants react with cellulose to form a protective char layer that reduces flammability and promotes char formation. Boric acid and borax are non-durable flame retardants that form a glassy polymer coating on the fiber surface, insulating the material from heat. The Layer- by- Layer (LbL) coating method involves applying multiple layers of flame-retardant chemicals to cellulose fibers, creating a porous and flame-retardant material without compromising the lightweight and breathable nature of the fibers. These treated cellulose fibers have various applications, such as in flame-resistant clothing for oil and gas workers, industrial fabrics like filters and protective coverings, and medical textiles such as bandages and surgical gowns [136-139],

[0482] This example focuses on banana “peduncle” fibers for further investigation (see FIG. 38). The fibers are processed and defibrillated at 700 bar pressure using a high-pressure homogenizer to increase their surface area. These defibrillated cellulose gels were utilized to create stable aerogel structures using freeze drying for flame retardant and oil absorbance properties. The initial studies include examining the aerogel's flame-retardant activity, oil absorption, oil retention properties, and porosity distribution.

[0483] Materials and Methods. Banana fiber pellets were ground in a knife miller and passed through a 60-sieve three times. Chitosan (Chi) of medium MW was acquired from Sigma Aldrich. Sodium bicarbonate (NaBC) was acquired from the spectrum. Bombax mori cocoons were obtained from Amazon. All chemicals used were of analytical grade.

[0484] Preparation of In-situ Banana-Chitosan Hydrogel (BCH). BCH was synthesized by a high-pressure homogenization method. First, a uniform 1% chitosan solution was prepared using a 2% acetic acid solution at 750 - 850 RPM speed and stirred for 2 days to get the uniform solution. BFP powder was added to the 1% chitosan solution at 1000 RPM to prepare homogenous dispersion. Then, the dispersion is heated to 100 °C and brought back to 70 °C. After getting the solution at 70 °C, the solution is homogenized at low or no pressure for 5 minutes, then the pressure is increased to 700 bars (10152.6 psi) for 20 minutes for proper defibrillation of BFP powder. At last, gel with a thick consistency was collected and stored in the refrigerator for further use after getting to ambient temperature.

[0485] Preparation of In-situ Banana-Silk-Chitosan Hydrogel (BSCH). BSCH was synthesized using a high-pressure homogenization method. First, a uniform 1% chitosan solution was prepared using a 2% acetic acid solution at 750 - 850 RPM speed and stirred for two days to get the uniform solution. Secondly, BFP powder and silk fibers (knife-milled with 60 size sieve 3 times from Bombax mori cocoons) were added to the 1% chitosan solution at 1000 RPM to prepare homogenous dispersion. Then, the dispersion is heated to 100 °C and brought back to 70 °C. After getting the solution at 70 °C, the solution is homogenized at low or no pressure for 5 minutes, then the pressure is increased to 700 bars (10152.6 psi) for 20 minutes for proper defibrillation of BFP and silk fiber powder. At last, gel with a thick consistency was collected and stored in the refrigerator for further use after getting to ambient temperature.

[0486] Preparation of Banana Chitosan Aerogel (BCA) and Banana Silk Chitosan Aerogel (BSCA). BCH and BSCH were aerated for 3 minutes using a high-speed stirrer at 20,000 rpm to create a stable foam. 10% sodium bicarbonate, by wet weight of hydrogel, is incorporated to enhance flame retardancy by thoroughly mixing at high speed. The structures were frozen at -20°C for at least 6 hours. Following this, they were freeze-dried at -80°C and 1 mbar pressure until completely dry, which took 7-11 hours (depending on the sample size). This process was carried out using the LABCONCO freeze-drying system.

[0487] Preparation of Aerogel Samples for Pore Analysis. BCA exhibits a higher density of pore distribution that spans from 470 microns to 2120 microns. In contrast, BSCA in leads to a wider range of pore sizes that span from 890 microns to 1824 microns. See FIG. 39 for a general outline of the aerogel synthesis process. FIGS. 40A and 40B for pore size distribution analysis.

[0488] Oil Absorbency. The innovative banana and silk in situ chitosan aerogel, rendered flame-retardant ability through the sodium bicarbonate treatment, exhibited remarkable oil absorbance and retention capabilities. This eco-friendly and sustainable material demonstrates a high affinity for oil, rapidly absorbing and retaining substantial quantities of motor oil. Its porous structure and hydrophobic nature (chitosan treatment) facilitated efficient oil uptake, while the chitosan treatment contributed to the absorption capacity. Notably, sodium bicarbonate imparted the aerogel flame retardant properties did not compromise its oil absorbency, making it fit for fire safety and oil absorption functionalities. ASTM F726-17 isused to test the aerogels' oil absorbency and oil retention ability [43, 140], Oil absorption and oil retention capacities of non-treated (FIGS. 41 A and 41 B) and treated aerogels are shown in FIGS. 41 C and 41 D (non-treated) and FIGS. 42A and 42B (treated).

[0489] An oil absorption test was conducted according to a modified ASTM F726-17 standard to investigate the oil absorption capability of banana aerogels. Dry aerogels with dimensions of 10 mm (diameter) and 13 mm (thickness) are first weighed and then immersed in 800 ml motor oil for two h to ensure a swelling equilibrium. The aerogels are lifted from the oil container by a stainless-steel mesh basket, drained in the air for 30 seconds, and weighed again. The oil absorption capacity of the aerogels is calculated using Equation 6 below:Qt = (mw — md) / md Eq. 6

[0490] Where Qt is the aerogel's oil absorption capacity at time t and md (g) and mw (g) are the aerogel weights before and after the oil absorption, respectively.

[0491] BCH and BSCH in 1 % chitosan solution were aerated for 3 minutes using a high-speed stirrer at 20,000 rpm. Once a stable foam dispersion was prepared, it was transferred to a suitable container. The containers were then frozen at -20°C for 4-6 hours. The samples were freeze-dried at -80°C at one mbar pressure until completely dry, using the LABCONCO freeze drying system, FREEZONE.

[0492] Flame Retardant Activity of the Aerogel. Sodium bicarbonate (NaBC) was strategically incorporated in a high-speed stirring step during the synthesis process to impart flameretardant properties to the aerogel. This addition of NaBC played a crucial role in enhancing the aerogel's fire safety, making it suitable for applications where fire hazards are a concern [137, 141], Visual results from flame retardant tests are depicted in FIGS. 43A-43D.

[0493] Without wishing to be bound by theory, the mechanism of flame-retardant activity of NaBC in the aerogel can be considered to be twofold. First, NaBC undergoes an endothermic decomposition reaction when exposed to heat or flames and releases carbon dioxide and water vapor. This reaction absorbs heat energy from the surrounding environment, effectively cooling the aerogel and reducing the temperature in the vicinity of the flame. Secondly, the carbon dioxide gas released during the endothermic process acts as an inert blanket, diluting the concentration of the flames [141-143],

[0494] The aerogel's porous structure facilitates the uniform distribution of NaBC throughout the material, ensuring efficient flame-retardant action throughout the entire aerogel matrix. This synergistic combination of the aerogel’s inherent properties and the flame-retardant properties of NaBC results in a material that exhibits excellent oil absorption and offers enhanced fire safety, making it a sustainable and better choice for environmental applications.

[0495] Conclusion. In conclusion, the use of aluminum containers for freezing hydrogel has proven to be significantly more efficient compared to other materials such as polystyrene and glass. This study optimized the hydrogel freezing processes, with the hydrogel being frozen in only 15 minutes at -80 °C and within 30 minutes at temperatures of -10 °C, -15 °C, and -20°C. Additionally, the banana aerogel and banana silk aerogel have different pore size distributions, while the addition of NaBC in 10% wet weight ratio with the hydrogel imparts excellent flame retardant properties without affecting the oil absorption or retention ability of the aerogel. Overall, these findings highlight the potential of aluminum containers and NaBC as effective tools and additives, respectively, for hydrogel and aerogel applications.8. Synthesis of Novel Photocatalysts Based on Nanocrystals and Cellulose for Photocatalytic Degradation of Dyes

[0496] Introduction. Oxide nanocrystals are one of those photocatalysts that are used for many different photocatalytic applications, such as removing textile dyes from water. However, one of the challenges is collecting oxide nanocrystals from water after using them as photocatalysts, especially on a large scale. They are very small and collecting with a filter is not possible, and consequently, they will cause the next issue. So, incorporating them in a natural, cheap substrate, which does not affect the photocatalytic ability of the nanocrystals, could be helpful. Cellulose nanofibers are one of the natural, cheap, and applicable materials that can be used as the initial material. On the other hand, a form of aerogel can be used to encapsulate nanoparticles into the cellulose nanofiber substrate because they are very light, with very high surface area due to a very porous surface, and a straightforward method to obtain. Disclosed in this example is a photocatalyst based on oxide nanocrystals and natural polymers that can be used for the degradation of different classes of textile dyes (e.g., cationic, anionic, azo, and reactive dyes) in aqueous environments under visible light. Disclosed are synthesis methods for the fabrication and modification of oxide nanocrystals, followed by their integration into aerogels and nanofibers composed of natural cellulose matrices.

[0497] Characterizing the Photocatalysts. X-ray diffraction (XRD) determines the crystallite structure and identifies the product. Transmission electron microscopy (TEM) and Field emission scanning electron microscopy (FESEM) are used to study the product's surface morphology and internal structure. The Fourier Transform Infrared Spectroscopy (FT-IR) is used to identify the functional groups. Energy-dispersive X-ray spectroscopy (EDS / EDX) and X-ray photoelectron spectroscopy (XPS) are applied to determine the product elements and the material's surface chemistry. Thermogravimetric Analysis (TGA) is used to determine the thermal stability of the product and identify the product. Dynamic light scattering (DLS) is used to measure the apparent size of the sample.

[0498] Photocatalytic Characterization. Diffuse reflectance spectroscopy determines the wavelength the product can absorb and the energy bandgap (Tauc’s plot). Photoluminescence (PL) measures the recombination of electrons from the conduction band to the valence band. Electron paramagnetic (EPR) is applied to identify the radicals produced during photocatalytic reactions. Brunauer-Emmett-Teller (BET) and Barrett-Joyner-Halenda (BJH) are used to measure the photocatalysts' surface area and the materials' porosity. Cyclic voltammetry (CV) is used to calculate the location of the conduction and valence bands. Photocurrentspectroscopy (PCS) is used to find out how fast the electrons in the photocatalysts respond to light.

[0499] Cyclic Voltammetry Measurement & Photocurrent Transition for Photocatalysts. A three-electrode system was used for cyclic voltammetry measurements: a reference electrode (3 M Ag / AgCI), a counter electrode (platinum wire), and a working electrode (glassy carbon electrode, d = 2 mm). The electrolyte solution consisted of chitosan dissolved in a 1% acetic acid solvent and shaken for three days to form a gel. It was filtered to separate the undissolved particles. Then, 5 mmol of iodine solution at 0.1 N was added to make the solution conductive and stirred for an additional 20 minutes to obtain a homogenized red solution. To improve the viscosity of the solution, it was heated at 60°C for 20 minutes, and after cooling, it was centrifuged to separate the non-dissolved particles. Finally, 0.3 g of sample was added and stirred for 20 minutes. The particles were dispersed in the solution. Subsequently, N2 gas was purged for 15 minutes before the experiment to saturate the surroundings. The scan rate was set at 0.01 V s-1, with two segments, a sensitivity of 1e-4A / V, and the potential window was set from -1 to -1.2 V. For photocurrent transition, at a potential of 0.8 V, a lamp produced the photocurrent transition. There was a range from 0 to 275 seconds for the off and on times.

[0500] EPR Analysis. EPR studies were performed at room temperature in the X-band using a Bruker EMXplus. The EPR resonator was filled with sample suspensions ranging in volume from 10-15 pL. The experimental parameters were microwave power of 0.6 mW, microwave frequency of 9.87 GHz, modulation amplitude of 0.04 Gs, and frequency of 100 kHz. NP(Sr) was suspended and exposed to optical irradiation using a 415 nm wavelength, one mJ optical parametric oscillator from Solar LS, and a 100 Hz repetition rate pulsed Nd: YAG LQ629 laser from the same source.

[0501] The EPR method was employed to detect the radical and its type, and Tiron (4,5- dihydroxy-1 ,3-benzene-disulfonic acid disodium salt, Sigma) was used as a probe. The Tiron concentration in the prepared solutions was 50-100 mM / L. Superoxide was created when NP(Sr) was exposed to visible light (1 mg per 60 pL of distilled water).

[0502] Materials. All the chemicals are purchased from Fischer or Aldrich. Titanium butoxide, chloride salt of sodium, cesium, rubidium, calcium, strontium, barium, magnesium, nickel, iron, copper, zinc, cobalt, Niobium, bismuth, tin, aluminum, indium, and cerium. Ethylenediamine, 1-butanol, DMF, NaOH, HCI, acetic acid, tetrabutylammonium hydroxide (TBAH), and ammonium peroxydisulfate.

[0503] Methodology. There are three phases of the synthesis, including the synthesis of oxide nanocrystals, the modification of oxide nanocrystals, and the encapsulation of oxide nanocrystals in the novel cellulosic composite in the form of aerogel and nanofiber.

[0504] Encapsulating the Oxide Nanocrystal in the Cellulosic Composite - Aerogel Form: In this phase, cellulose nanofiber (CNF) was used as a substrate for encapsulation of the obtained nanoparticles from the previous phases. Three gels with different concentrationswere made through mixing CNF and chitosan (2% Chitosan+1 % NFC (A(2%), 1% Chitosan+1 % NFC(A(1%), 0.5% Chitosan+1 %NFC(A(0.5%)). To make the gel, first different concentration of chitosan was made (2%chitosan+2% acetic acid, 1%chitosan+2% acetic acid, and 0.5%chitosan+2% acetic acid). Then, each of the chitosan solution was mixed with 1% of NFC powder and increased the temperature to 90°C. When the solution got the corresponding temperatures was cooled to 70 °C. Finally, a homogenizer (high pressure) was used to make the gel. It was set for 30 minutes at a pressure of 700 bar. The final product was a white gel, which was used as a substrate for encapsulating the nanoparticle.

[0505] In this step, Nsh2(Sr), which was a good photocatalyst (based on the photocatalytic degradation test), was mixed with different gels. Nsh2(Sr) is titanium oxide doped with strontium, cerium, and nitrogen and surface modified with tetrabutylammonium hydroxide (TBAOH) (TiSrCeNO surface modified with TBAOH). The amount of Nsh2 (Sr) was the same as the amount of chitosan in each sample. For a 50 g of solution, in the case of A(2%), 1.041 g Nsh2(Sr) was added (A(2%)@NP), and mixed for 4 days at room temperature with 500 RPM, it was 0.52g in the case of A(1%) (A(1%)@NP), and in the case of A(0.5%) it was 0.26 g (A(0.5%)@NP). Then, after 4 days of mixing, a very uniform yellow color gel was obtained, and it was transferred into an aluminum dish and kept at -83 °C for 24h. Then, the frozen gel was transferred to freeze-drying at 1MPa for 48h. The result was a very light aerogel which was encapsulated with Nsh2(Sr).

[0506] After obtaining the samples, they were tested as photocatalysts for removing textile dye from water, and the most promising result was taken for the next step. It was encapsulated into A(1%)@NP. The amount of NP was 1 % in the previous samples for all of them. For the optimization, the amount of Nsh1(Sr) was 0.25% (A(1 %)@NP(0.25%),0.5%(A(1%)@NP(0.5%), 2%(A(1%)@NP(2%), and 4%(A(1%)@NP(4%). The result confirmed that (A(1%)@NP(1 %) had the highest efficiency (FIGS. 44A-44C).

[0507] It is worth noting that the pure aerogels of each concentration without encapsulation of nanoparticles were also obtained with the same method as the encapsulating case, and a white aerogel form was obtained for each concentration.

[0508] Encapsulated Oxide Nanocrystal in Cellulose Nanofiber. The diffuse reflectance spectroscopy of (pure aerogel and nanoparticle encapsulated aerogel) was carried out between 200nm-800nm (FIG. 45A and 45B). The pure aerogel shows high absorption in the UV region and less absorption in the visible region, including A(0.5%) (0.5% chitosan+1 % CNF), A(1 %) (1 % chitosan+1 % CNF), and A(2%) (2% chitosan+1 % CNF). While all the samples show visible wavelength absorption, including A(2%)@NP ( 2%chitosan+1%NFC + 2% NP), A(1%)@NP (1%chitosan+1 %NFC + 1% NP), and A(0.5%)@NP(0.5%chitosan+1 %NFC + 0.5% NP). A(1%)@NP and A(2%)@NP show more absorption.

[0509] FIGS. 46A and 46B present the FTIR spectra of pure and nanoparticle-encapsulated aerogel with varying chitosan concentrations. In the pure aerogel, several key functionalgroups associated with CNF and chitosan can be identified and tracked across the samples (FIG. 46A). A broad peak observed around 3400 cm-1corresponds to the stretching vibrations of hydroxyl (O-H) and amine (N-H) groups, indicative of hydrogen bonding within and between CNF and chitosan chains. As the chitosan content increases, this band becomes broader and more intense, reflecting enhanced hydrogen bonding and increased availability of - NH2groups.

[0144] The band near 2920 cm-1is attributed to C-H stretching vibrations of aliphatic CH2groups, present in both CNF and chitosan backbones.

[0145] This region remains relatively stable but slightly increases in intensity with higher chitosan content. A distinct peak at -1650 cm-1appears more clearly at 1 % and 2% chitosan levels, corresponding to the Amide I band (C=O stretching of the acetamide group), confirming the presence of partially acetylated chitosan.

[0146] Similarly, the 1590 cm-1peak (Amide II, NH2bending) becomes more prominent with increasing chitosan content, supporting the incorporation of free amine groups.

[0144] The 1450 cm-1and 1370 cm-1peaks arise from CH2bending and CH3bending, respectively, common to both polymers. These bands exhibit a marginal shift and intensity change, suggesting intermolecular interactions and rearrangement within the composite matrix.

[0146] A strong band around 1155 cm-1is characteristic of C-O-C antisymmetric stretching, representative of p-1 ,4-glycosidic linkages in cellulose. This band remains prominent throughout all compositions, indicating the structural integrity of CNF.

[0145] Additionally, a region between 1030-1070 cm-1corresponds to C-0 stretching vibrations, while a small but noticeable peak at -895 cm-1confirms the presence of p-glycosidic linkages, a hallmark of cellulose-based materials.

[0144]

[0510] Overall, these spectral features confirm the successful integration of chitosan into the CNF matrix and the preservation of key functional groups. Notably, the increase in amide- related bands with chitosan concentration validates its proportional incorporation.

[0511] In the case of the nanoparticle-encapsulated aerogel, new peaks emerge around 600- 800 onr , which are attributed to metal-oxygen (M-O) stretching vibrations and confirm successful incorporation (FIGS. 46A and 46B). Additionally, Amide I and II bands (-1650 and -1590 cm-1) show slight intensity changes and possible shifts, suggesting intermolecular interactions between chitosan’s amide groups and nanoparticle surfaces. The broad O-H / N- H band (-3400 cm-1) is also influenced, reflecting enhanced hydrogen bonding or surface interactions. Collectively, these spectral modifications validate the structural impact of nanoparticle encapsulation on the polymer matrix.

[0512] A microscopic image of the pure and nanoparticle-encapsulated aerogels was taken to study the morphology of the surface and cross-section (FIGS. 47A-47F and 48A-48F). In the pure aerogels, the surface showed that by increasing the amount of chitosan, a more rigid surface is obtained, and the number of holes on the surface is lower in the aerogel with higher chitosan concentration. The cross-section images showed that a more uniform structure is obtained by increasing the amount of chitosan. In the case of nanoparticle-encapsulatedaerogel, it appears that NPs were uniformly encapsulated into the substrate of the pure aerogels, and the surface of the samples is more rigid compared to their pure case (FIGS. 48A-48F).

[0513] The EDS analysis of the nanoparticle-encapsulated aerogels showed that all the elements belonging to the composite (Sr, N, Ce, Ti, C, and O) exist in the materials (FIGS. 49A-49C).

[0514] The Thermal analysis gravimetry (TGA) was carried out to determine the behavior of the pure aerogel and nanoparticle-encapsulated aerogel against the temperature (FIGS. 50A and 50B). It shows that in the case of pure aerogel, there are four main reductions, including 10%, 22%, 68%-71%, and 100%, which happened at 61°C, 255°C, 363°C-377°C, and 580°C- 600°C.

[0515] Reduction at 60 °C is because of evaporation of physically adsorbed water in the matrix. Most of the weight was lost because of the decomposition of chitosan and the partial degradation of cellulose backbones at 255°C . In addition, the onset temperature and peak degradation shifted slightly with chitosan concentration, which indicates that the higher chitosan concentration (A(2%)) causes an increase in thermal stability because of earlier chain scission. The char residue increases slightly with higher chitosan concentration, attributed to chitosan’s higher carbonaceous residue after degradation, which is because of the nitrogenrich structure and crosslinking by increasing the temperature.

[0516] After encapsulating NPs, the thermal resistance of the materials remarkably improved, as evidenced by increased char residue and delayed degradation. A(1%)@NP and A(2%)@NP showed the highest stability, where the remaining weight after reaching 600°C was around 50%. While it was around 20% in the case of A(0.5%)@NP. The improvement in thermal stability is related to the introduction of nanoparticles into the polymer matrix, which avoids chain scission and volatilization.

[0517] Photocatalytic Performance Evaluation. The photocatalytic reaction was conducted in a lab-made photocatalytic reactor (FIGS. 52A-52B). First, 0.0167 gL'1of dye was prepared (in 60 ml of water) and stirred for 4 hours. 3 ml of the solution was withdrawn before adding the photocatalyst and exposing it to light (1stwithdraw). Then, 0.03 g of photocatalyst was added for 20 min in the dark (2ndwithdrawal). Then, the solution was exposed to an LED (300W, 3.63 mW / cm2intensity; VPCRT6; on the roof of the box) for the next 2h (3rdto 8thwithdraw). Xenon lamps are the nearest example of sunlight intensity due to their high intensity. It produces high temperatures, requires more expensive facilities, and is less safe than LED lamps. So, if a photocatalyst can work under low-intensity LED, its mimic under sunlight is even more promising.

[0147] Finally, UV-Vis spectroscopy was carried out to measure the photocatalytic degradation and all the kinetic data. The absolute intensity of the LED lamp is calculated. The absolute intensity of the lamp used in this experiment was calculated (Table 17). The resultshowed that the lamp has an even lower intensity than the standard LED lamp used for photocatalytic degradation (Calculated under the table).

[0148] Table 17. Characteristics of light sources used in photocatalytic studies, including LEDs, xenon lamps, and natural sunlight, showing power, spectral distribution, and intensity.

[0518] Lamp Luminous Flux: 0=45,000 Im

[0519] Electrical Power: Peiectricai=300 W

[0520] Luminous Efficacy: q= / Peiectricai =45,000lm / 300W=150 Im / W

[0521] Radiant Power: 25% efficiency: Pradiant=Peiectricaix0.25=300 Wx0.25=75 W

[0522] Distance from Lamp to Beaker: d=0.5 m=50 cm

[0523] Box Size: 16.5 inx27 in=41.91 cmx68.58cm

[0524] Beam Angle: Since the lamp is mounted on the roof and focused on the beaker, the angle is 90°.

[0525] Calculate the Illuminated Area at the Beaker. For a 90° beam angle, the light spreads in a circular footprint. The radius of the circle at the beaker's level is:

[0526] R=d-tan(0 / 2)=50-tan(45°)=80.98 cm

[0527] The illuminated area (A) is: A=TTR2=TT(80.98)2=20606.26 cm2

[0528] Calculate Light Intensity. The light intensity (I) in milliwatts per square centimeter (mW / cm2) is given by: l=Pradiantx1000 / A -^1=75x1000 / 20606.26 = 3.63 mW / cm2.

[0529] Photocatalytic Degradation of MB by Cellulosic Composite. In the first step, the photocatalytic ability of the nanoparticle-encapsulated aerogel was explored through degrading MB in a neutral environment (FIGS. 53A-53E). In the first step, the proper concentration for removing MB from water was tested. Based on the result, A(1%)@NPshowed the highest degradation (55%) compared to A(2%)@NP and A(0.5%)@NP with the same efficiency of 25%. So, A(1%)@NP was used for the next step.

[0530] In the next step, different amount of Nsh2(Sr) were encapsulated into the cellulose substrate to optimize the proper amount of nanocrystals. A(1%)@NP(0.25%), A(1%)@NP(0.5%), A(1%)@NP(1%), A(1 %)@NP(2%), and A(1 %)@NP(4%) were obtained, as mentioned in the synthesis section. Then, they were used for photocatalytic degradation of MB in a neutral environment (FIGS. 54A-54E). The overall result confirmed that by increasing the amount of oxide nanocrystals, the efficiency of the composite for the degradation of MB was also increased. The highest efficiency was obtained by A(1%)@NP(4%) which was around 80%, and the lowers efficiency was obtained by A(1%)@NP(0.25%), which was around 25%. The result confirmed that the efficiency of the Nsh2(Sr) was not remarkably changed.

[0531] Photocatalytic Degradation of RD120 by Cellulosic Composite. The photocatalytic degradation of A(1 %)@NP(1%) was tested with degrading RD120 in different environments (FIG. 55A-55H). A(1%)@NP(4%), which was the best sample for degrading MB, was not used in this experiment, and instead A(1 %)@NP(1 %) was used with a smaller amount of Nsh2(Sr). However, a remarkable degradation of RD120 was observed in both acidic and neutral environments. The result confirmed that this composite is able to remove 100% of RD120 in the acidic environment, 85% in the neutral environment, and around 30% in the basic environment.

[0532] The Stability of the Photocatalysts. In the case of cellulose composite, besides the stability of the catalyst in different photocatalytic cycles, the stability in different environments needed to be tested because it was made of a composite containing CNF, chitosan, and oxide nanocrystals, which usually provide a weaker stability. So, we tested the composite in different pH environments, from a very acidic environment (pH=2) to a highly basic environment (pH=12). The result illustrated a high stability in all the environments after 2h of stirring in the RD120 solution with different pH levels, except for pH=2, which made a partial collapse (FIGS. 56A-56G). This test provides useful insight because in the textile industry, different agents make the final water have a pH of not just neutral but also acidic and basic. However, it is worth noting that based on the safety rule, the wastewater obtained from the textile industry should be neutralized to have a pH level between 6 and 7.H. REFERENCES

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[0685] It should be emphasized that the above-described embodiments of the present disclosure are merely possible examples of implementations set forth for a clear understanding of the principles of the disclosure. Many variations and modifications may be made to the above-described aspects. All such modifications and variations are intended to be included herein within the scope of this disclosure and protected by the following claims.

Claims

CLAIMSWhat is claimed:

1. A method for producing an aerogel, comprising: mixing together a polymeric material, a solvent, and an additional agent to form a slurry, wherein the additional agent is selected from a plasticizer, a crosslinking agent, or a combination thereof; homogenizing the slurry to form a hydrogel; aerating the hydrogel to form a foam; freezing the foam at a temperature of about -90 °C to about -10 °C; and freeze-drying the foam at a pressure of about 0.1 mbar to about 1 mbar and a temperature of about -90 °C to about -20 °C to form an aerogel; wherein the polymeric material comprises at least one biopolymer, at least one biopolymer material, or a combination thereof.

2. The method of claim 1 , wherein the foam is frozen for about 0.1 hours to about 30 hours.

3. The method of claim 1 , wherein the foam is frozen for about 1 hours to about 60 hours.

4. The method of any one of claims 1-3, wherein the foam is frozen at a temperature of about -30 °C to about -10 °C.

5. The method of any one of claims 1-3, wherein the foam is frozen at a temperature of about -90 °C to about -70 °C.

6. The method of any one of claims 1-5, wherein the foam is freeze-dried for about 1 hour to about 20 hours.

7. The method of any one of claims 1-6, wherein the foam is freeze-dried at a temperature of about -50 °C to about -20 °C.

8. The method of any one of claims 1-6, wherein the foam is freeze-dried at a temperature of about -90 °C to about -60 °C.

9. The method of any one of claims 1-8, wherein forming the slurry further comprises: mixing together the polymeric material, the solvent, and the additional agent at a temperature of about 80 °C to about 110 °C; and allowing the slurry to cool prior to homogenizing.

10. The method of claim 9, wherein the slurry is allowed to cool to a temperature of about 60 °C to about 80 °C prior to homogenizing.

11. The method of any one of claims 1-10, wherein the method further comprises allowing the hydrogel to cool to a temperature of about 2 °C to about 20 °C prior to aerating the hydrogel.

12. The method of claim 11 , wherein the hydrogel is allowed to cool for about 2 hours to about 20 hours.

13. The method of any one of claims 1-12 wherein the foam is placed into a container prior to freezing or prior to freeze-drying.

14. The method of any one of claims 1-12, wherein the foam is coated onto a surface to form a foam layer prior to freezing or prior to freeze-drying, wherein the surface comprises a textile, a paper, or a polymer film.

15. The method of claim 14, wherein an additional layer comprising a textile, a paper, or a polymer film is placed onto the foam layer prior to freezing and freeze-drying.

16. The method of claim 14 or claim 15, wherein the foam layer has a thickness of from about 1 mm to about 5 mm.

17. The method of any one of claims 1-16, wherein the slurry comprises the plasticizer in a weight ratio of plasticizer to polymeric material of about 1 :20 to about 1 :10.

18. The method of claim 17, wherein the plasticizer comprises an anionic cellulose derivative, a nonionic cellulose derivative, glycerol, sorbitol, xylitol, polyethylene glycol, a natural oil, lactic acid, a derivative of starch, triethyl citrate, diethyl phthalate, propylene glycol, or a combination thereof.

19. The method of claim 17, wherein the plasticizer comprises carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, glycerol, sorbitol, xylitol, polyethylene glycol, a natural oil, lactic acid, a derivative of starch, triethyl citrate, diethyl phthalate, propylene glycol, or a combination thereof.

20. The method of claim 17, wherein the plasticizer comprises carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropylmethyl cellulose, glycerol, and any combination thereof.

21. The method of any one of claims 1-20, wherein the slurry comprises the crosslinking agent in a weight ratio of the crosslinking agent to the polymeric material of about 1 : 10 to about 1 :1.

22. The method of claim 21 , wherein the crosslinking agent comprises chitosan, phytic acid, citric acid, tannic acid, calcium chloride, glutaraldehyde, transglutaminase, sodium alginate, lignin, a polyphenol, genipin, or a combination thereof.

23. The method of any one of claims 1-22, wherein the at least one biopolymer comprises lignin, cellulose, hemicellulose, nanocellulose, silk fibroin, or any combination thereof.

24. The method of any one of claims 1-23, wherein the at least one biopolymer material comprises algal biomass, wool fiber, lignocellulosic biomass, or a combination thereof.

25. The method of any one of claims 1-24, wherein at least one additional material selected from a phase-changing material, silica, photocatalytic nanoparticles, a second biopolymer material, a flame retardant, and any combination thereof, is incorporated into the slurry, incorporated into the hydrogel prior to aerating, or incorporated into the foam prior to freezing.

26. The method of any one of claims 1-25, wherein the slurry comprises the at least one biopolymer and the plasticizer; wherein the at least one biopolymer comprises cellulose and the plasticizer comprises the anionic cellulose derivative, the nonionic cellulose derivative, or a combination thereof.

27. The method of claim 26, further comprising incorporating a phase-changing material into the foam prior to freezing.

28. The method of claim 27, wherein the phase-changing material is selected from the group consisting of eutectics, salt hydrates, organic materials, and high-temperature salts.

29. The method of claim 27, wherein the phase-changing material is selected from the group consisting of sodium acetate, 1 ,2-benzisothiazol-3(2H)-one, and a combination thereof.

30. The method of any one of claims 26-29, wherein the method further comprises incorporating silica into the foam prior to freezing.31 . The method of any one of claims 1-26, wherein the method further comprises mixing algal biomass with the hydrogel prior to aerating.

32. The method of claim 31 , wherein the algal biomass is mixed with the hydrogel prior to aerating at a weight ratio of hydrogel to algal biomass of about 1 :4 to about 3:1 .

33. The method of claim 31 or claim 32, wherein the algal biomass is a cyanobacteria.

34. The method of claim 31 or claim 32, wherein the algal biomass is a nostoc cyanobacteria.

35. The method of any one of claims 31-34, wherein the slurry further comprises the at least one biopolymer comprising silk fibroin.

36. The method of any one of claims 1-25, wherein the slurry comprises the at least one biopolymer and the crosslinking agent; wherein the at least one biopolymer comprises cellulose and the crosslinking agent comprises chitosan.

37. The method of claim 36, wherein the slurry further comprises the at least one biopolymer material comprising wool fiber.

38. The method of claim 36, wherein the slurry further comprises the plasticizer further comprising glycerol.

39. The method of any one of claims 1-36, wherein the method further comprises mixing the hydrogel with photocatalytic nanoparticles prior to aerating.

40. The method of any one of claims 1-36 or claim 39, wherein the photocatalytic nanoparticles are mixed with the hydrogel in a nanoparticle to additional agent weight ratio of about 1 :4 to about 4:1.

41. The method of claim 39 or claim 40, wherein the photocatalytic nanoparticles are mixed with the hydrogel for about 1 hour to about 7 days.

42. The method of any one of claims 39-41 , wherein the photocatalytic nanoparticles are titanium oxide nanoparticles.

43. The method of any one of claims 1-25, wherein the slurry comprises the at least one biopolymer material and the crosslinking agent; wherein the at least one biopolymer material comprises lignocellulosic biomass and the crosslinking agent comprises chitosan.

44. The method of claim 43, wherein the lignocellulosic biomass comprises banana biomass.

45. The method of claim 43 or claim 44, wherein the slurry further comprises the at least one biopolymer comprising silk fibroin.

46. The method of any one of claims 43-45, wherein the crosslinking agent further comprises phytic acid.

47. The method of any one of claims 43-45, wherein the method further comprises incorporating phytic acid into the hydrogel prior to aerating.

48. The method of any one of claims 43-45, wherein the method further comprises incorporating photocatalytic nanoparticles into the foam prior to freezing.

49. The method of claim 48, wherein the photocatalytic nanoparticles are oxide nanoparticles.

50. The method of claim 49, wherein the oxide nanoparticles are titanium oxide nanoparticles.51 . The method of any one of claims 36-45, wherein the method further comprises incorporating a flame retardant into the slurry or into the hydrogel prior to aerating.

52. The method of claim 51 , wherein the flame retardant is selected from sodium bicarbonate, ammonium polyphosphate, melamine, zinc borate, hydrated magnesium hydroxide, aluminum trihydrate, a bio-based polyphosphate, a tannin, a silica aerogel, clay nanoparticles, borax, an intumescent composition, or a combination thereof.

53. The method of any one of claims 1-52, wherein the aerogel has a porosity of greater than about 85%.

54. The method of any one of claims 1-52, wherein the aerogel has a porosity of from about 85% to about 95%.

55. The method of any one of claims 1-54, wherein the aerogel has a specific surface area of at least 200 m2 / g.

56. The method of any one of claims 1-54, wherein the aerogel has a specific surface area of about 200 m2 / g to about 1500 m2 / g.

57. The method of any one of claims 1-56, wherein the aerogel has an apparent density of about 0.003 g / cm3to about 0.5 g / cm3.

58. The method of any one of claims 1-57, wherein the aerogel has an intrinsic thermal resistance of about 0.001 °Cm2 / Wto about 0.02 °Cm2 / W.

59. The method of any one of claims 1-58, wherein the aerogel comprises nanocellulose material comprising cellulose nanofibrils, cellulose nanocrystals, or a combination thereof.

60. A method for producing an aerogel, comprising: mixing together a polymeric material, solvent, and an additional agent to form a slurry, wherein the additional agent is selected from a plasticizer, chitosan, or a combination thereof; homogenizing the slurry to form a hydrogel; aerating the hydrogel to form a foam; freezing the foam at a temperature of about -90 °C to about -10 °C; and freeze-drying the foam at a pressure of about 0.1 mbar to about 1 mbar and a temperature of about -90 °C to about -20 °C to form an aerogel; wherein the polymeric material comprises at least one biopolymer, at least one biopolymer material, or a combination thereof.61 . The method of claim 60, wherein the foam is frozen for about 0.1 hours to about 12 hours.

62. The method of claim 60, wherein the foam is frozen for 5 hours to about 12 hours.

63. The method of any one of claims 60-62, wherein the foam is frozen at a temperature of about -30 °C to about -10 °C.

64. The method of any one of claims 60-62, wherein the foam is frozen at a temperature of about -90 °C to about -70 °C.

65. The method of any one of claims 60-64, wherein the foam is freeze-dried for about 1 hour to about 20 hours.

66. The method of any one of claims 60-65, wherein the foam is freeze-dried at a temperature of about -50 °C to about -20 °C.

67. The method of any one of claims 60-65, wherein the foam is freeze-dried at a temperature of about -90 °C to about -60 °C.

68. The method of any one of claims 60-67, wherein forming the slurry further comprises: mixing together the polymeric material, the solvent, and the additional agent at a temperature of about 80 °C to about 110 °C; and allowing the slurry to cool prior to homogenizing.

69. The method of claim 68, wherein the slurry is allowed to cool to a temperature of about 60 °C to about 80 °C prior to homogenizing.

70. The method of any one of claims 60-69, wherein the foam is placed into a container prior to freezing or prior to freeze-drying.71 . The method of any one of claims 60-69, wherein the foam is coated onto a surface to form a foam layer prior to freezing and freeze-drying, wherein the surface comprises a textile, a paper, or a polymer film.

72. The method of claim 71 , wherein an additional layer comprising a textile, a paper, or a polymer film is placed onto the foam layer prior to freezing and freeze-drying.

73. The method of claim 71 or claim 72, wherein the foam layer has a thickness of from about 1 mm to about 5 mm.

74. The method of any one of claims 60-73, wherein the slurry comprises the plasticizer in a weight ratio of plasticizer to polymeric material of about 1 :20 to about 1 :10.

75. The method of any claim 74, wherein the plasticizer comprises an anionic cellulose derivative, a noniononic cellulose derivative, or a combination thereof.

76. The method of claim 74, wherein the plasticizer comprises carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl methyl cellulose, and any combination thereof.

77. The method of any one of claims 60-76, wherein the slurry comprises chitosan in a weight ratio of chitosan to the polymeric material of about 1 : 10 to about 1 :1.

78. The method of any one of claims 60-77, wherein the at least one biopolymer comprises lignin, cellulose, hemicellulose, nanocellulose, silk fibroin, or any combination thereof.

79. The method of any one of claims 60-77, wherein the at least one biopolymer comprises cellulose, nanocellulose, or a combination thereof.

80. The method of any one of claims 60-79, wherein the at least one biopolymer material comprises algal biomass, lignocellulosic biomass, or a combination thereof.

81. The method of claim 80, wherein the lignocellulosic biomass comprises from about 10 wt% to about 99 wt% cellulose and from about 1 wt% to about 50 wt% lignin.

82. The method of any one of claims 60-81 , wherein at least one additional material selected from a phase-changing material, silica, photocatalytic nanoparticles, a second biopolymer material, and any combination thereof, is incorporated into the slurry, incorporated into the hydrogel prior to aerating, or incorporated into the foam prior to freezing.

83. The method of any one of claims 60-82, wherein the slurry comprises the at least one biopolymer and the plasticizer; wherein the at least one biopolymer comprises cellulose and the plasticizer comprises the anionic cellulose derivative, the nonionic cellulose derivative, or a combination thereof.

84. The method of claim 83, further comprising incorporating a phase-changing material into the foam prior to freezing.

85. The method of claim 84, wherein the phase-changing material is selected from the group consisting of eutectics, salt hydrates, organic materials, and high-temperature salts.

86. The method of claim 84, wherein the phase-changing material is selected from the group consisting of sodium acetate, 1 ,2-benzisothiazol-3(2H)-one, and a combination thereof.

87. The method of any one of claims 83-86, wherein the method further comprises incorporating silica into the foam prior to freezing.

88. The method of any one of claims 60-83, wherein the method further comprises mixing algal biomass with the hydrogel prior to aerating.

89. The method of claim 88, wherein the algal biomass is mixed with the hydrogel prior to aerating at a weight ratio of hydrogel to algal biomass of about 1 :4 to about 3:1.

90. The method of claim 88 or claim 89, wherein the algal biomass is a cyanobacteria.91 . The method of claim 88 or claim 89, wherein the algal biomass is a nostoc cyanobacteria.

92. The method of any one of claims 60-91 , wherein the slurry further comprises the at least one biopolymer comprising silk fibroin.

93. The method of any one of claims 60-82, wherein the slurry comprises the at least one biopolymer material and chitosan; wherein the at least one biopolymer material comprises lignocellulosic biomass.

94. The method of claim 93, wherein the lignocellulosic biomass comprises banana biomass.

95. The method of claim 93 or claim 94, wherein the slurry further comprises the at least one biopolymer comprising silk fibroin.

96. The method of any one of claims 93-95, wherein the method further comprises incorporating photocatalytic nanoparticles into the foam prior to freezing.

97. The method of claim 96, wherein the photocatalytic nanoparticles are oxide nanoparticles.

98. The method of claim 97, wherein the oxide nanoparticles are titanium oxide nanoparticles.

99. The method of any one of claims 60-98, wherein the aerogel has a porosity of greater than about 85%.

100. The method of any one of claims 60-98, wherein the aerogel has a porosity of from about 85% to about 95%.

101. The method of any one of claims 60-100, wherein the aerogel has a specific surface area of at least 200 m2 / g.

102. The method of any one of claims 60-100, wherein the aerogel has a specific surface area of about 200 m2 / g to about 1500 m2 / g.

103. The method of any one of claims 60-102, wherein the aerogel has an apparent density of about 0.003 g / cm3to about 0.5 g / cm3.

104. The method of any one of claims 60-103, wherein the aerogel has an intrinsic thermal resistance of about 0.001 °C m2 / W to about 0.02 °C m2 / W.

105. The method of any one of claims 60-104, wherein the aerogel comprises nanocellulose material comprising cellulose nanofibrils, cellulose nanocrystals, or a combination thereof.

106. A composition, comprising: a biopolymer, a biopolymer material, or a combination thereof; and an additional agent selected from a plasticizer, a crosslinking agent, or a combination thereof; wherein the plasticizer comprises an anionic cellulose derivative, a nonionic cellulose derivative, glycerol, sorbitol, xylitol, polyethylene glycol, a natural oil, lactic acid, a derivative of starch, triethyl citrate, diethyl phthalate, propylene glycol, or a combination thereof; and wherein the crosslinking agent comprises chitosan, phytic acid, citric acid, tannic acid, calcium chloride, glutaraldehyde, transglutaminase, sodium alginate, lignin, a polyphenol, genipin, or a combination thereof.

107. The composition of claim 106, wherein the plasticizer comprises carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropyl cellulose, hydroxypropylmethyl cellulose, glycerol, sorbitol, xylitol, polyethylene glycol, a natural oil, lactic acid, a derivative of starch, triethyl citrate, diethyl phthalate, propylene glycol, or a combination thereof.

108. The composition of claim 106, wherein the plasticizer comprises carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropylmethyl cellulose, glycerol, and any combination thereof.

109. The composition of any one of claims 106-108, wherein the composition is from about 0.1 % to about 20% plasticizer by weight.

110. The composition of any one of claims 106-108, wherein the composition is from about 0.1 % to about 15% plasticizer by weight.

111. The composition of any one of claims 106-110, wherein the composition is from about 0.1 % to about 10% crosslinking agent by weight.

112. The composition of any one of claims 106-110, wherein the composition is from about 0.1 % to about 5% crosslinking agent by weight.

113. The composition of any one of claims 106-112, wherein the biopolymer comprises lignin, cellulose, hemicellulose, nanocellulose, silk fibroin, or any combination thereof.

114. The composition of any one of claims 106-113, wherein the composition is from about 0.01% to about 99% of the biopolymer by weight.

115. The composition of any one of claims 106-113, wherein the composition is from about 20% to about 50% of the biopolymer by weight.

116. The composition of any one of claims 106-113, wherein the composition is from about 60% to about 80% of the biopolymer by weight.

117. The composition of any one of claims 106-116, wherein the biopolymer materialcomprises algal biomass, wool fiber, lignocellulosic biomass, or a combination thereof.

118. The composition of any one of claims 106-117, wherein the composition is from about 0.1 % to about 90% of the biopolymer material by weight.

119. The composition of any one of claims 106-117, wherein the composition is from about 0.1 % to about 70% of the biopolymer material by weight.

120. The composition of any one of claims 106-117, wherein the composition is from about 0.1 % to about 50% of the biopolymer material by weight.

121. The composition of any one of claims 106-120, wherein the composition further comprises at least one additional material selected from a phase-changing material, silica, photocatalytic nanoparticles, a second biopolymer material, a flame retardant, and any combination thereof.

122. The composition of any one of claims 106-121 , wherein the composition comprises the biopolymer and the plasticizer; wherein the biopolymer comprises nanocellulose in the form of cellulose nanofibrils, cellulose nanocrystals, or a combination thereof and the plasticizer comprises the anionic cellulose derivative, the nonionic cellulose derivative, or a combination thereof.

123. The composition of claim 122, wherein the composition further comprises at least one phase-changing material at a weight ratio of phase-changing material to nanocellulose of about 1 :2 to about 4:5.

124. The composition of claim 123, wherein the at least one phase-changing material is selected from the group consisting of eutectics, salt hydrates, organic materials, and high- temperature salts.

125. The composition of claim 123, wherein the at least one phase-changing material is selected from the group consisting of sodium acetate, 1 ,2-benzisothiazol-3(2H)-one, and a combination thereof.

126. The composition of any one of claims 122-125, wherein the composition further comprises from about 1% to about 10% silica by weight.

127. The composition of any one of claims 106-122, wherein the composition comprises the biopolymer material and the plasticizer; wherein the biopolymer material comprises algal biomass and the plasticizer comprises the anionic cellulose derivative, the nonionic cellulose derivative, or a combination thereof.

128. The composition of claim 127, wherein the algal biomass is a cyanobacteria.

129. The composition of claim 127, wherein the algal biomass is a nostoc cyanobacteria.

130. The composition of any one of claims 127-129, wherein the composition is from about0.1% to about 70% of algal biomass by weight.

131. The composition of any one of claims 127-130, wherein the composition furthercomprises the biopolymer comprising silk fibroin.

132. The composition of claim 131 , wherein the composition is from about 10 wt% to about 99 wt% silk fibroin by weight.

133. The composition of any one of claims 106-120, wherein composition comprises the biopolymer and the crosslinking agent; wherein the biopolymer comprises nanocellulose in the form of cellulose nanofibrils, cellulose nanocrystals, or a combination thereof and the crosslinking agent comprises chitosan.

134. The composition of claim 133, wherein the composition further comprises the biopolymer material comprising wool fiber.

135. The composition of claim 134, wherein the composition is from about 0.1% to about 10% of wool fiber by weight.

136. The composition of claim 134 or claim 135, wherein the composition has a thermal resistance of greater than about 2 °C m2 / W.

137. The composition of claim 133, wherein the composition further comprises the plasticizer comprising glycerol.

138. The composition of claim 137, wherein the composition has a water absorption capacity of about 30 g of water / g of the composition to about 65 g of water / g of composition.

139. The composition of claim 133, wherein the composition further comprises photocatalytic nanoparticles.

140. The composition of claim 139, wherein the photocatalytic nanoparticles are titanium oxide nanoparticles.

141. The composition of claim 139 or claim 140, wherein the composition comprises the photocatalytic nanoparticles in a weight ratio of chitosan to photocatalytic nanoparticles of about 1 :4 to about 4:1.

142. The composition of any one of claims 106-120, wherein composition comprises the biopolymer material and the crosslinking agent; wherein the biopolymer material comprises lignocellulosic biomass and the crosslinking agent comprises chitosan.

143. The composition of claim 142, wherein the lignocellulosic biomass comprises banana biomass.

144. The composition of claim 143, wherein the composition is from about 0.1% to about 10% of the banana biomass by weight.

145. The composition of any one of claims 142-144, wherein the composition further comprises the biopolymer comprising silk fibroin.

146. The composition of claim 145, wherein the composition is from about 10 wt% to about99 wt% silk fibroin by weight.

147. The composition of any one of claims 133-146, wherein the crosslinking agent further comprises phytic acid.

148. The composition of claim 147, wherein the composition is from about 0.1 % to about 10% of phytic acid by weight.

149. The composition of any one of claims 142-144, wherein the composition further comprises photocatalytic nanoparticles.

150. The composition of claim 149, wherein the photocatalytic nanoparticles are oxide nanoparticles.

151. The composition of claim 150, wherein the oxide nanoparticles are titanium oxide nanoparticles.

152. The composition of any one of claims 133-146, wherein the composition further comprises a flame retardant.

153. The composition of claim 152, wherein the flame retardant is selected from sodium bicarbonate, ammonium polyphosphate, melamine, zinc borate, hydrated magnesium hydroxide, aluminum trihydrate, a bio-based polyphosphate, a tannin, a silica aerogel, clay nanoparticles, borax, an intumescent composition, or a combination thereof154. The composition of claim 152 or claim 153, wherein the composition is from about 0.1% to about 20% of the flame retardant by weight.

155. The composition of claim 152 or claim 153, wherein the composition is from about 0.1% to about 10% of the flame retardant by weight.

156. The composition of any one of claims 106-155, wherein the composition has a porosity of greater than about 85%.

157. The composition of any one of claims 106-155, wherein the composition has a porosity of from about 85% to about 95%.

158. The composition of any one of claims 106-157, wherein the composition has a specific surface area of at least 200 m2 / g.

159. The composition of any one of claims 106-157, wherein the composition has a specific surface area of about 200 m2 / g to about 1500 m2 / g.

160. The composition of any one of claims 106-159, wherein the composition has an apparent density of about 0.003 g / cm3to about 0.5 g / cm3.

161. A composition, comprising: a biopolymer, a biopolymer material, or a combination thereof; and an additional agent selected from a plasticizer, a crosslinking agent, or a combination thereof;wherein the plasticizer comprises an anionic cellulose derivative, a nonionic cellulose derivative, or a combination thereof; and wherein the crosslinking agent comprises chitosan, phytic acid, citric acid, tannic acid, calcium chloride, glutaraldehyde, transglutaminase, sodium alginate, lignin, a polyphenol, genipin, or a combination thereof.

162. The composition of claim 161 , wherein the plasticizer comprises carboxymethyl cellulose, methyl cellulose, hydroxyethyl cellulose, hydroxypropylmethyl cellulose, and any combination thereof.

163. The composition of claim 161 or claim 162, wherein the composition is from about 0.1 % to about 20% plasticizer by weight.

164. The composition of claim 161 or claim 162, wherein the composition is from about 1 % to about 15% plasticizer by weight.

165. The composition of any one of claims 161-164, wherein the composition is from about 0.1% to about 10% crosslinking agent by weight.

166. The composition of any one of claims 161-164, wherein the composition is from about 0.1% to about 5% crosslinking agent by weight.

167. The composition of any one of claims 161-166, wherein the biopolymer comprises lignin, cellulose, hemicellulose, nanocellulose, silk fibroin, or any combination thereof.

168. The composition of any one of claims 161-167, wherein the composition is from about 0.01 % to about 99% of the biopolymer by weight.

169. The composition of any one of claims 161-167, wherein the composition is from about 20% to about 50% of the biopolymer by weight.

170. The composition of any one of claims 161-167, wherein the composition is from about 60% to about 80% of the biopolymer by weight.

171. The composition of any one of claims 161-170, wherein the biopolymer material comprises algal biomass, lignocellulosic biomass, or a combination thereof.

172. The composition of any one of claims 161-171 , wherein the composition is from about 0.1% to about 90% of the biopolymer material by weight.

173. The composition of any one of claims 161-171 , wherein the composition is from about 0.1% to about 70% of the biopolymer material by weight.

174. The composition of any one of claims 161-171 , wherein the composition is from about 0.1% to about 50% of the biopolymer material by weight.

175. The composition of any one of claims 161-174, wherein the composition further comprises at least one additional material selected from a phase-changing material, silica, photocatalytic nanoparticles, a second biopolymer material, and any combination thereof.

176. The composition of any one of claims 161-175, wherein the composition comprises the biopolymer and the plasticizer; wherein the biopolymer comprises nanocellulose in the form of cellulose nanofibrils, cellulose nanocrystals, or a combination thereof and the plasticizer comprises the anionic cellulose derivative, the nonionic cellulose derivative, or a combination thereof.

177. The composition of claim 176, wherein the composition further comprises at least one phase-changing material at a weight ratio of phase-changing material to nanocellulose of about 1 :2 to about 4:5.

178. The composition of claim 177, wherein the at least one phase-changing material is selected from the group consisting of eutectics, salt hydrates, organic materials, and high- temperature salts.

179. The composition of claim 177, wherein the at least one phase-changing material is selected from the group consisting of sodium acetate, 1 ,2-benzisothiazol-3(2H)-one, and a combination thereof.

180. The composition of any one of claims 176-179, wherein the composition further comprises from about 1% to about 10% silica by weight.

181. The composition of any one of claims 161-176, wherein the composition comprises the biopolymer material and the plasticizer; wherein the biopolymer material comprises algal biomass and the plasticizer comprises the anionic cellulose derivative, the nonionic cellulose derivative, or a combination thereof.

182. The composition of claim 181 , wherein the algal biomass is a cyanobacteria.

183. The composition of claim 181 , wherein the algal biomass is a nostoc cyanobacteria.

184. The composition of any one of claims 181-183, wherein the composition is from about0.1% to about 70% of algal biomass by weight.

185. The composition of any one of claims 181-184, wherein the composition further comprises the biopolymer comprising silk fibroin.

186. The composition of claim 185, wherein the composition is from about 10 wt% to about 99 wt% silk fibroin by weight.

187. The composition of any one of claims 161-174, wherein composition comprises the biopolymer material and the crosslinking agent; wherein the biopolymer material comprises lignocellulosic biomass and the crosslinking agent comprises chitosan.

188. The composition of claim 187, wherein the lignocellulosic biomass comprises banana biomass.

189. The composition of claim 188, wherein the composition is from about 0.1 % to about 10% of the banana biomass by weight.

190. The composition of any one of claims 187-189, wherein the composition furthercomprises the biopolymer comprising silk fibroin.

191. The composition of claim 190, wherein the composition is from about 10 wt% to about 99 wt% silk fibroin by weight.

192. The composition of any one of claims 187-189, wherein the composition further comprises photocatalytic nanoparticles.

193. The composition of claim 192, wherein the photocatalytic nanoparticles are oxide nanoparticles.

194. The composition of claim 193, wherein the oxide nanoparticles are titanium oxide nanoparticles.

195. The composition of any one of claims 161-194, wherein the composition has a porosity of greater than about 85%.

196. The composition of any one of claims 161-194, wherein the composition has a porosity of from about 85% to about 95%.

197. The composition of any one of claims 161-196, wherein the composition has a specific surface area of at least 200 m2 / g.

198. The composition of any one of claims 161-196, wherein the composition has a specific surface area of about 200 m2 / g to about 1500 m2 / g.

199. The composition of any one of claims 161-198, wherein the composition has an apparent density of about 0.003 g / cm3 to about 0.5 g / cm3.

200. The composition of any one of claims 161-199, wherein the composition has an intrinsic thermal resistance of about 0.001 °C m2 / Wto about 0.02 °C m2 / W.

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