High-performance barrier or optical materials by programming entropy-driven nanosheet growth

Abstract

Nanocomposite materials comprising nanoparticles, small molecules, and block copolymer (BCP)-based supramolecules are provided. The nanoparticles, small molecules, and BCP-based supramolecules self-assemble into a plurality of nanosheets that form the multilayer nanocomposite material. The nanoparticle, small molecule, and BCP-based supramolecule can be ZrO2, 3-pentadecylphenol (PDP), polystyrene-block-poly(4-vinyl pyridine)(PDP)1, respectively. Methods for producing the nanocomposite materials by contacting the nanoparticles, small molecules, and BCP-based supramolecules with a solvent and drying to remove the solvent to allow self-assembly are also provided. The nanocomposite materials provided herein can be used as barrier materials against volatile organic compounds, water, oxygen, or electron, and can be used as coating and packaging materials on various substrates, or as optical materials.

Description

HIGH-PERFORMANCE BARRIER OR OPTICAL MATERIALS BY PROGRAMMING ENTROPY-DRIVEN NANOSHEET GROWTHInventors: Ting Xu, Emma Vargo, Le MaCROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Application No. 63 / 519,162, filed on August 11, 2023, the content of which is incorporated herein by reference in its entirety.STATEMENT OF GOVERNMENT SUPPORT

[0002] This invention was made with government support under Contract No. DE-AC02- 05CH11231 awarded by the U.S. Department of Energy. The government has certain rights in this invention.TECHNICAL FIELD

[0003] This disclosure relates generally to nanocomposites and barrier or optical materials.BACKGROUND

[0004] 2D nanosheets are common motifs in natural materials. Despite extensive efforts to design layered self-assemblies of nanosheets based on block copolymers (BCPs) and nanoparticles or liquid crystals, a mismatch remains between what is made and what is needed. Materials based on easily accessible nanosheets, a few to tens of nm in thickness, have generally performed poorly for instance to serve as viable components for optical, barrier and dielectric applications.

[0005] Engineering nanomaterials to satisfy requirements at the system level, including, but not limited to, feature size, chemistry, multifunctionality, processing, integration compatibility, scalability and life cycle is needed. However, requirements narrow the design options. While BCPs with nonlinear chain architectures, such as stars or bottlebrushes, can expand the range of accessible feature sizes and overcome the kinetic barrier associated with long-chain entanglements, their synthesis is demanding. Driven by optimizing intermolecular interactions, current designs are too rigid to plug in new chemical functionalities and cannot mitigate condition differences during integration. Despite extensive optimization of building blocks and treatments, accessing nanostructures with the required feature sizes and chemistries is difficult. Programming their growth across the nano-to-macro hierarchy also remains challenging. The rigidity of existing designs limits programmable nanomaterial growth.BRIEF SUMMARY

[0006] Provided herein are high performance barrier coatings and methods of fabricating such coatings by programming a micro-then-nano growth sequence in ternary nanocomposite blends. Thecoatings are composed of > 200 stacked nanosheets (about 125 nm in sheet thickness) with defect densities < 0.056 pm-2and -98% efficiency in controlling the defect type. High molecular-weight polymers (nearly 500 kDa) are used as the nanocomposite’s matrix. Contrary to common perception, polymer chain entanglements are advantageous to realize long-range order, accelerate the fabrication process (< 30 minutes), and satisfy specific requirements to advance multi-layered film technology. Specifically, the coatings exhibit high-performance barrier properties against volatile organic compounds, water, and oxygen for use as packaging. They can also be applied as electron barriers for use as dielectric capacitors. These composite coatings have built-in recyclability and provide solutions to recycling issues associated with existing metallized and multi-layered films. The long chains’ entanglement provides mechanical robustness such that chemical crosslinks are not needed. They are amenable to cycles of assembly, disassembly, and reassembly without compromising structure integrity, highlighting the advantages of bottom -up material synthesis.

[0007] In one aspect, provided herein is a nanocomposite material comprising nanoparticles, small molecules, and block copolymer (BCP)-based supramolecules, self-assembled into a plurality of nanosheets that form the nanocomposite material. The BCP -based supramolecules contain BCPs and small molecules.

[0008] In some embodiments, each of the BCP -based supramolecules comprises a BCP and small molecules bound to the BCP via non-covalent bonds. In some embodiments, the BCP comprises a molecular weight of about 130 kDa to about 600 kDa. In specific embodiments, the BCP is a high molecular weight polymer (e.g., having a molecular weight of about 500 kDa or greater).

[0009] In some embodiments, the small molecules are organic molecules. In embodiments, small molecules contain a molar mass of about 50 g / mol to about 1500 g / mol.

[0010] In some embodiments, the nanoparticles are inorganic molecules, such as metal oxide nanoparticles [e.g., zirconium oxide (ZrC )], noble metal nanoparticles (e.g., gold), or silica nanoparticles. In some embodiments, the nanoparticles is about 3 nm to about 50 nm in size, about 3 nm to about 9 nm in size, or about 6 nm in size.

[0011] In specific embodiments, the nanoparticles comprise ZrCE. In specific embodiments, the small molecules comprise 3 -pentadecylphenol (PDP). In specific embodiments, the BCP comprises polystyrene-Woc -poly(4-vinyl pyridine) (PS-6-P4VP). In specific embodiments, the BCP -based supramolecules comprise PS- / i-P4VP(PDP)i. which contains PDP bound to pyridine side chains of the PS- / 1-P4VP via hydrogen bonding.

[0012] In some embodiments, the nanoparticles comprise about 3-20% volume, the small molecules comprise about 10-25% volume, and BCP-based supramolecules comprise about 65-75% volume of the nanocomposite material. Example compositions of the nanocomposite material are set forth in Table 1.

[0013] In some embodiments, each nanosheet is about 50 nm to about 410 nm thick, such as about 50 nm to about 150 nm thick, or about 125 nm thick.

[0014] In some embodiments, the nanocomposite material comprises about 20 to about 100, about 20 to about 200, or about 200 or greater number of nanosheets.

[0015] In some embodiments, the nanocomposite material comprises about 0.06 pm-2or less defect density, and about 98% efficiency in controlling the defect type.

[0016] In some embodiments, the nanocomposite material provided herein comprises an improved barrier function against a volatile organic compound (VOC), water, oxygen, and / or electron relative to a control material. In some embodiments, the nanocomposite material has VOC removal efficiency of 40% or more, water vapor transmission rate (WVTR) of 8 g nr2day ’or less, dielectric breakdown strength of 500 MV / nr1or more, maximum discharged energy density of 3 J cm'3or more, and / or encapsulant lifetime of 3 min pm1or more.

[0017] In some embodiments, the nanocomposite material has the plurality of nanosheet with a gradient layer thickness, e.g., thinner layers toward the substrate-nanocomposite material interface and thicker layers away from the substrate. In some embodiments, the thickness of nanosheets in the nanocomposite material ranges from about 65 nm to about 135 nm (e.g., from about 72 nm to about 126 nm), from about 120 nm to about 280 nm (e.g., from about 151 nm to about 223 nm), from about 120 nm to about 250 nm (e.g., from about 127 nm to about 221 nm), or from about 120 nm to about 410 nm (e.g., from about 135 nm to about 370 nm).

[0018] In some embodiments, the nanocomposite material has alternating layers of a nanoparticlerich nanosheet and a nanoparticle -poor nanosheet.

[0019] In one aspect of the present disclosure, provided herein is a method of producing a nanocomposite material. The method includes contacting an initial blend of nanoparticles, small molecules, and block copolymer (BCP)-based supramolecules with a solvent to form a mixture, and drying the mixture to remove the solvent, forming via a self-assembly process the nanocomposite material comprising a plurality of nanosheets containing the nanoparticles, the small molecules, and the BCP -based supramolecules. The BCP-based supramolecules contains BCPs and small molecules.

[0020] In some embodiments, the solvent is chloroform or benzene.

[0021] In some embodiments, contacting includes contacting the initial blend of nanoparticles, small molecules, and BCP-based supramolecules with the solvent that is about 95% to about 100% volume, or about 97.5% volume of the mixture (i.e., the initial blend is about 5% or less, or about 2.5% volume of the mixture).

[0022] In some embodiments, drying includes removing the solvent to initiate the self-assembly process at a volume percent of solvent in the mixture of about 70% to about 80% or lower. The selfassembly process can occur when a volume percent of solvent in the mixture is about 70% to 80% or less.

[0023] In some embodiments, drying process takes from about 20 minutes to about 3 days.

[0024] In some embodiments, the method further includes adjusting the drying rate and / or solute / solvent ratio in the mixture to adjust thickness and / or color of the plurality of nanosheets. Aslower drying rate or a higher solute ratio in the mixture can generate a thicker and / or redder colored nanosheet.

[0025] In some embodiments, the mixture is drop-cast onto a substrate before drying the mixture. In some embodiments, the substrate is a solid, a lens, a membrane, a fdm, or a wafer made of Teflon, polyester, silicon, or glass.

[0026] In some embodiments, each of the BCP -based supramolecules comprises a BCP and small molecules bound to the BCP via non-covalent bonds.

[0027] In some embodiments, the BCP comprises a molecular weight of about 130 kDa to about 600 kDa.

[0028] In some embodiments, the small molecules are organic molecules comprising a molar mass of about 50 g / mol to about 1500 g / mol.

[0029] In some embodiments, the nanoparticles are inorganic molecules, such as metal oxide nanoparticles [e.g., zirconium oxide (ZrC )], noble metal nanoparticles (e.g., gold), or silica nanoparticles. In some embodiments, the nanoparticles is about 3 nm to about 50 nm in size, about 3 nm to about 9 nm in size, or about 6 nm in size.

[0030] In specific embodiments, the nanoparticles comprise ZrCE. In specific embodiments, the small molecules comprise 3 -pentadecylphenol (PDP). In specific embodiments, the BCP comprises polystyrene-Woc -poly(4-vinyl pyridine) (PS-6-P4VP). In specific embodiments, the BCP -based supramolecules comprise PS- / i-P4VP(PDP)i. which contains PDP bound to pyridine side chains of the PS- / 1-P4VP via hydrogen bonding.

[0031] In some embodiments, each nanosheet is about 50 nm to about 410 nm thick, such as about 50 nm to about 150 nm thick, or about 125 nm thick.

[0032] In some embodiments, the nanocomposite material comprises about 20 to about 100, about 20 to about 200, or about 200 or greater number of nanosheets.

[0033] In some embodiments, the nanocomposite material comprises about 0.06 pm2or less defect density, and about 98% efficiency in controlling the defect type.

[0034] In some embodiments, the nanoparticles comprise about 3-20% volume, the small molecules comprise about 10-25% volume, and BCP-based supramolecules comprise about 65-75% volume of the initial blend. Example compositions of the initial blend are set forth in Table 1.

[0035] In some embodiments, forming includes forming alternating layers of a nanoparticle-rich nanosheet and a nanoparticle-poor nanosheet.

[0036] In one aspect of the present disclosure, provided is a nanocomposite material produced by the method provided herein.

[0037] In one aspect of the present disclosure, provided is a product containing the nanocomposite material of provided herein, or the nanocomposite material produced by the method provided herein, wherein the product is a barrier product or an optical product.

[0038] In some embodiments, the product includes, and can be used as, a volatile organic compound barrier, a water barrier, an oxygen barrier, an electron barrier, a dielectric capacitator, a lens coating, and / or a packaging (e.g., food wrapper), a light filter, a flat lens, and a zone plate.

[0039] Details of one or more embodiments of the subject matter described in this specification are set forth in the accompanying drawings and the description below. Other features, aspects, and advantages will become apparent from the description, the drawings, and the claims. Note that the relative dimensions of the following figures may not be drawn to scale.BRIEF DESCRIPTION OF THE DRAWINGS

[0040] The patent or application file contains at least one drawing executed in color. Copies of this patent or patent application publication with color drawing(s) will be provided by the Office upon request and payment of the necessary fee.

[0041] FIG. 1A schematically depicts systems engineering of layered nanosheets as barrier materials. To transform stacked nanosheets into high-performance barrier coatings, the assemblies need to satisfy numerous requirements. FIG. IB depicts sequential nanosheet growth during film casting. Sequential growth follows a nano-to-micro-to-macro sequence and forms the smallest feature sizes when the system mobility is the highest. FIG. 1C depicts programmed nanosheet growth during film casting. Programmed growth matches the system mobility with the targeted feature size and organizes molecular aggregates into a microframework when the system mobility is high. The nanostructures will subsequently grow within the microframework by means of short-range diffusion when the system mobility is low.

[0042] FIGs. 2A-2I depict transmission electron microscopy (TEM) images of variations on the S2 / NP blend formulation. FIG. 2A depicts S2 supramolecules with 6 vol% 5 nm iron oxide nanoparticles. FIG. 2B depicts 330-b-125 kDa supramolecules formed using a different hydrogenbonding small molecule, I-PDP (inset). This is the blend used for energy-dispersive X-ray spectroscopy (EDS) analysis in FIG. 3. FIG. 2C depicts 330-b-125 kDa supramolecules formed using a blend of hydrogen-bonding small molecules (PDP) and non-hydrogen-bonding small molecules (DID) at molar ratios of 1 and 0.6, respectively. FIGs. 2D-2I depict S2 / NP blends self-assembled on a variety of substrates: a Teflon beaker (FIG. 2D), a porous Teflon membrane (FIG. 2E), a polyester fdm (FIG. 2F), a thick silicon wafer (FIG. 2G), a thin silicon wafer (FIG. 2H), and glass (FIG. 21).

[0043] FIG. 3 depicts the EDS analysis of the small molecule distribution in a S2 / NP blend with iodine-labelled PDP (I-PDP). The structural and chemical information is collected using a high-angle annular dark-field set-up, so the contrast is reversed compared with the other TEM images provided herein. The brightest pixels are those that scatter most strongly, so the nanoparticle-filled domains are lighter than the organic-only domains. The iodine map shows that I-PDP are distributed throughout all microdomains, despite the enthalpic driving force for them to segregate into the P4VP(PDP) domains. By comparison, the ZrCf nanoparticles are strictly partitioned into the P4VP(PDP) domains. Thisimaging technique does not differentiate between hydrogen-bonded and unbonded small molecules, so the P4VP(PDP) domains have an overall higher concentration of small molecules.

[0044] FIGs. 4A-4C depict quantification of the nanosheet growth kinetic pathway. FIG. 4A depicts SANS profiles of 5 vol% and 10 vol% S2 / NP solutions in deuterated chloroform fitted with Guinier-Porod models. FIG. 4B depicts USANS profile of the 10 vol% S2 / NP solution. The inset shows a liquid-cell TEM image of ribbon-like aggregates. Scale bar, 500 nm. FIG. 4C depicts USAXS profiles of 10 vol% S2 / NP and S3 / NP solutions. At this concentration, the S3 / NP solution has formed microscale aggregates, indicated by the presence of low-q features. FIGs. 4D-4F depict results from an in situ SAXS-XPCS experiment used to quantify system mobility during nanosheet growth. Roman numerals i-v refer to the assembly stages during the solvent drying. FIG. 4D depicts SAXS profiles showing the structural evolution from a dilute solution to highly ordered lamellae. FIG. 4E depicts nanoparticle diffusion mode evolution during S2 / NP assembly process based on Kohlrausch exponent y values extracted using kinetics data from qs to ql. Each data point is labelled with a filled circle. Note that y could not be calculated for stages iii and v, owing to the presence of sharp scattering peaks. These stages are labelled chronologically with open circles. FIG. 4F depicts comparison of relaxation times rs (at qs = 0.3 nm ) and rl (at ql = 0.03 nm ' ) for each assembly stage during nanosheet growth. FIG. 4G depicts in situ GTSAXS of a Slcyl / NP solution under optimized drying conditions. At is used to label the elapsed time after aggregate formation (leftmost panel). FIG. 4H depicts cross-sectional TEM of S2 / NP films quenched at labelled solvent fractions. Scale bars, 1 pm. The bottom-right panel is a false-colored image of the film quenched at 28 vol%, for which color is used to label the length of each nanosheet extending past the image boundaries, a.u., arbitrary units.

[0045] FIG. 5A depicts an example automated sheet-length analysis and FIG. 5B depicts a semiautomated defect-density analysis, both performed on the S2 film frozen at 40 vol%. Junction and ends were identified automatically. U-turn defects were labelled manually.

[0046] FIGs. 6A-6F depict programmed nanosheet growth leading to long-range order and defect control. FIG. 6A depicts cross-sectional TEM image of a S2 / NP coating containing more than 200 stacked nanosheets. Within the approximately 2,660 pm2imaged area, there are only 149 defects: 146 paired ends (blue circles), two paired U-turns (pink square) and one junction (gold triangle). A photograph of a S2 / NP coating on a polyester film is shown in the inset. FIG. 6B depicts higher- magnification TEM images of the S2 / NP film showing high-aspect-ratio nanosheets containing densely packed nanoparticles. FIG. 6C depicts higher-magnification TEM images of each defect type. FIG. 6D depicts comparison of defect densities from cross-sectional TEM images of Sl / NP and S2 / NP with literature values from BCP thin films. FIG. 6E depicts cross-sectional TEM image of a S2 / NP blend that dried too quickly for microframework formation; disordered microdomains and nanoparticle aggregates are observed. FIG. 6F depicts cross-sectional TEM image of a S3 / NP film with 20 vol% nanoparticles and a microdomain periodicity of 174 nm. Scale bars, 100 nm.

[0047] FIGs. 7A-7H depict performance evaluation of nanocomposite coatings as barrier materials. FIGs. 7A-7D depict representative TEM images of S2 / NP (FIG. 7A), S2dls / NP (FIG. 7B), S2 (FIG.7C), and Sl / NP (FIG. 7D) used to establish chemistry-structure-barrier property relationships. Scale bars, 500 nm. FIG. 7E depicts VOC barrier performance for S2 / NP, S2dls / NP, S2, and Sl / NP coatings on porous Teflon membranes. The removal efficiencies for five VOC molecules are shown, n = 2 for each bar. FIG. 7F depicts WVTRs of PET films with S2 / NP, S2dls / NP, S2 and Sl / NP coatings. S2 / NP coatings have the lowest rate of water transmission, n = 3 for each bar. FIG. 7G depicts dielectric breakdown strength (solid bars) and maximum discharged energy density (open bars) for S2 / NP, S2dls / NP, S2, and Sl / NP coatings. Biaxially oriented polypropylene (BOPP) is shown as a reference, n = 10 for each bar. FIG. 7H depicts encapsulant lifetimes of S2 / NP and two commercial UV-cured epoxies measured using electrical calcium tests. The results are normalized by barrier layer thickness, n = 3 for each bar. In all panels, error bars denote ±1 standard deviation.

[0048] FIGs. 8A-8D depict 8 stability analysis of the nanocomposite coatings. FIG. 8A depicts that, when a film is dried, redissolved and then recast, it forms the same lamellar structure as before. FIG. 8B depicts nanoindentation results showing that S2 / NP films are mechanically stable despite the lack of chemical crosslinks between layers. FIG. 8C depicts cyclic buckling tests (n = 600) of S2 / NP on a PET film showing that the film remains intact without any delamination from the substrate. FIG. 8D depicts disordered nanocomposites (S2dls / NP) and lamellae without nanoparticles (S2) both had inferior properties to S2 / NP (FIG. 8B), although all tested films had the same thickness and were supported by the same PET film.

[0049] FIGs. 9A-9E depict formation of gradient layer thicknesses in a lamellar nanocomposite. FIG. 9A schematically depicts the supramolecular nanocomposite system, which is diluted in a nonselective solvent and drop-cast to produce ordered lamellar structures. The concentration gradients present in the film during drop-casting affects the gradient layer thickness in the nanocomposite. The parameter f, used to describe the local layer thickness, is visually defined in the rightmost panel. FIG. 9B depicts images of fully-dried lamellar nanocomposite films taken under normal laboratory lighting. The different structural colors indicate processing-dependent nanostructures. From left to right, the samples were given increasing time to self-assemble. Each sample is ~1.5 cm along its horizontal edge. FIGs. 9C-9E depict cross-sectional TEM images of selected nanocomposites. As suggested by their structural colors, the dried films have substantially different internal structures. Each film also exhibits a height-dependent f gradient. Images are oriented so that the substrate-film interface is at the bottom, and the film-air interface is the wavy top boundary. All scale-bars are 1 pm.

[0050] FIGs. 10A-10D depict scattering characterization of f gradient formation. FIG. 10A depicts in situ SAXS profiles of a slowly-dried supramolecular nanocomposite solution. Tan lines show the evolution from correlation hole to ordered lamellae. The gold line shows the first sign of f gradient formation. The brown lines show the evolution of stronger f gradients. FIG. 10B depicts combined SAXS and USAXS profiles of dried nanocomposite films with varying nanostructures, shifted vertically for clarity. Curves are colored by the structural color of the dried sample, shown in the bottom right panel. Peaks i and i* are from the USAXS results, and define the average f through the films’ thickness. Peak ii is from the 6 nm nanoparticles. FIG. 10C depicts WAXS profiles fromsolution measurements on a capillary with spatially-varied solvent concentration. Structural color was used to label the location on the capillary where each measurement was collected; the capillary is shown in the top right panel. Peak iii describes the amount of crystallized PDP present in the sample. Peaks iv and v are from the NP ligands, and their intensity is roughly proportional to the solute concentration. FIG. 10D depicts WAXS profdes of the same samples shown in FIG. 10B.

[0051] FIGs. 11A-11G depict gradient structures at the nanoscale, microscale, and macroscale. FIG. 11 A depicts cross-sectional TEM image of a film with a distinct periodicity gradient and no NPs. FIG. 11B depicts measured domain widths for the coil, comb, and total f across the same region shown above. FIG. 11C depicts the raw domain size data plotted as coil and comb fractions of the total microdomain volume. Dashed lines were calculated directly from the sample composition for comparison to the experimental data. From the film bottom to the top, most of the unbonded PDP from the coil domains to the comb domains. FIG. 11D depicts optical micrograph of the rough texture observed in f gradient films. FIG. HE depicts optical micrograph of the substrate edge (lower black boundary) of a dried film. As the film dried, it receded from the edge rather than staying pinned. This effect is pronounced in slowly-dried films, and may be a macroscopic side-effect of the laterally- shrinking top layers. FIG. HF depicts TEM image of the top surface of a gradient film. End defects are labeled with blue teardrops pointing along the continuous lamella. No paired end-to-end defects are observed. FIG. 11G depicts TEM image of the bottom interface of a gradient film. A mixture of paired end-to-end defects and isolated end defects are observed.

[0052] FIGs. 12A-12H depict optical micrographs of six composition control films, and descriptions of their surface texture. FIG. 12A depicts a film with no NPs, no excess PDP, rapid drying; smooth. FIG. 12B depicts a film with NPs, no excess PDP, rapid drying; smooth. FIG. 12C depicts a film with no NPs, excess PDP, rapid drying; subtle texture. FIG. 12D depicts a film with no NPs, no excess PDP, slow drying; subtle texture. FIG. 12E depicts a film with NPs, no excess PDP, slow drying; smooth. FIG. 12F depicts a film with no NPs, excess PDP, slow drying; significant texture. FIG. 12G depicts a cross-sectional TEM image of the film shown top-down in FIG. 12D; there is no obvious f gradient and the surface is locally smooth. FIG. 12H depicts a cross-sectional TEM image of lower-molecular-weight S2 supramolecules under slow drying conditions; an f gradient is clearly present. FIG. 121 depicts a cross-sectional TEM image of the lowest-molecular- weight S3 supramolecules under slow drying conditions; a morphological transition to cylindrical domains has occurred. FIG. 12 J depicts a cross-sectional TEM of SI supramolecules dried over three days; a high- ( conformation has been achieved through the full fdm thickness, so no gradient is present. FIG. 12K depicts a cross-sectional TEM of Sl / NP nanocomposite dried over 3 days; there is no visible gradient structure. In the inset, the extending comb domains leave some NPs behind at the coil-comb interface as they pack more tightly and eject the other NPs, forming a 3 -layered structure.

[0053] FIG. 13 depicts solvent fraction vs. time curves for gradient and non-gradient films. Solvent fraction values in drying films are based on Filmetrics F20 interferometry measurements. The top curve shows slow drying over a 60 minute interval, which would lead to gradient formation. Thebottom two curves show faster drying processes, and would not lead to gradient formation. The data are fit with exponential decay functions for interpolation.

[0054] FIG. 14A depicts reflectance spectra collected across thicker gradient films. Insets: the films are ~3 mm across and 30 pm thick. Spectra are colored with the structural color observed for each reflectance measurement. FIG. 14B depicts optical microscope images of the region where every reflectance spectrum was collected.DETAILED DESCRIPTION

[0055] Reference will now be made in detail to some specific examples of the invention including the best modes contemplated by the inventors for carrying out the invention. Examples of these specific embodiments are illustrated in the accompanying drawings. While the invention is described in conjunction with these specific embodiments, it will be understood that it is not intended to limit the invention to the described embodiments. On the contrary, it is intended to cover alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.

[0056] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present invention. Particular example embodiments of the present invention may be implemented without some or all of these specific details. In other instances, well known process operations have not been described in detail in order not to unnecessarily obscure the present invention.

[0057] Various techniques and mechanisms of the present invention will sometimes be described in singular form for clarity. However, it should be noted that some embodiments include multiple iterations of a technique or multiple instantiations of a mechanism unless noted otherwise.

[0058] The terms “about” or “approximate” and the like are synonymous and are used to indicate that the value modified by the term has an understood range associated with it, where the range can be ± 20%, ± 15%, ± 10%, ± 5%, or ± 1%. The terms “substantially” and the like are used to indicate that a value is close to a targeted value, where close can mean, for example, the value is within 80% of the targeted value, within 85% of the targeted value, within 90% of the targeted value, within 95% of the targeted value, or within 99% of the targeted value.

[0059] As used herein with respect to a parameter, the term “decreased” or “decreasing” or “decrease” or “reduced” or “reducing” or “reduce” or “lower” refers to a detectable (such as at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, 90%, 95%, 96%, 97%, 98%, 99%, or 100%) negative change in the parameter from a comparison control, such as an established normal or reference level of the parameter, or an established standard control. Accordingly, the terms “decreased,” “reduced,” and the like encompass both a partial reduction and a complete reduction compared to a control.

[0060] As used herein with respect to a parameter, the term “increased” or “increasing” or“increase” or “enhanced” or “enhancing” or “enhance” or “greater” refers to a detectable (such as at least about 5%, 10%, 15%, 20%, 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%.80%, 85%, 90%, 95%, 100%, 200%, 300%, 400%, 500%, 600%, 700%, 800%, 900%, or 1000%) positive change in the parameter from a comparison control, such as an established normal or reference level of the parameter, or an established standard control.A. Nanocomposite Materials

[0061] Provided herein is a nanocomposite material comprising nanoparticles, small molecules, and block copolymer (BCP)-based supramolecules, self-assembled into a plurality of nanosheets that form the nanocomposite material. The BCP -based supramolecules contain BCPs and small molecules. A “nanocomposite” material as used herein refers to a heterogeneous material in which the characteristic length scale of the fdler material is typically in the nanometer range, such as materials formed by a blend of nanoparticles, small molecules, and BCP-based supramolecules provided herein.

[0062] The new nanomaterial design provided herein offers an improvement over the previously available nanosheet technology by providing (1) the ability of entropy-driven assemblies to accommodate variations in reactant composition and pair interactions during processing and integration and (2) the system mobility matched with the necessary diffusion of the building blocks to form targeted structures. As shown in FIG. IB, the previously available technology of sequential growth follows a nano-to-micro growth process, in which the smallest structure features form when the system mobility is the highest and vice versa. In contrast, the growth pathway provided herein proceeds in a reversed, micro-first-nano-later sequence (FIG. 1C): microstructures are defined first when the system has the highest mobility, followed by nanostructure formation through local organization of building blocks. Entropy-driven phase behavior helps realize this large-to-small growth pathway. It allows the system to form microscopic aggregates in dilute solutions when the system is mobile enough to organize large-scale structures. Thermodynamically, the entropy-driven phase behaviors seen in high-entropy alloys offer formulation flexibility while maintaining structure fidelity. Thus, target nanostructures can form using many combinations of locally available components when the system mobility is low. The coatings exhibit high-performance barrier properties against volatile organic compounds, water and oxygen for use as packaging, as well as against electrons for use as dielectric capacitors.

[0063] The BCP can comprise a molecular weight of about 130 kDa to about 600 kDa, such as about 130 kDa, about 200 kDa, about 300 kDa, about 400 kDa, about 450 kDa, about 500 kDa, about 560 kDa, or about 600 kDa. As specific examples, the BCPs can have molecular weights of 134 kDa, 455 kDa, and 557 kDa, as listed in Table 1. In specific embodiments, the BCP is a high molecular weight polymer (e.g., having a molecular weight of about 100, 200, 300, 400, or 500 kDa or greater).

[0064] The long-polymer-chain entanglements provided by high molecular weight polymers serve several roles: they program the kinetic pathway to match the mobility of the system with its stages ofstructure evolution and modulate the local defect morphology. By using high-molecular-weight building blocks, the blend forms molecular aggregates in a more dilute solution. This provides sufficient system mobility to organize molecular aggregates into extended microframeworks for subsequent nanostructure formation. The long-chain entanglements increase the kinetic stability and integrity of the aggregates during subsequent growth and organization. Long-chain entanglement can slow down local reorganization at the defect sites and, thus, maintain end-to-end pair-defect morphology.

[0065] The BCP -based supramolecules can each comprise a BCP and small molecules bound to the BCP via non-covalent bonds. For example, BCP-based supramolecules can be constructed by non- covalently attaching small molecules to polymer side chains. The presence of small molecules eliminates the need to modify either the nanoparticle ligand or polymer for nanoparticle incorporation and improve inter-particle ordering within BCP microdomains. 1-, 2- and 3-D nanoparticle arrays can be obtained in thin fdms of supramolecular nanocomposites via solvent annealing for a range of nanoparticles or nanoparticle mixtures. Kinetically, the presence of small molecules also provides opportunities to manipulate the energy landscape of the assembly process and to accelerate the assembly kinetics so that inherent properties of nanoparticles can be maintained and continuous thin film processing techniques can be implemented for device fabrication.

[0066] The small molecules can be organic molecules. Small molecules can contain a molar mass of about 50 g / mol to about 1500 g / mol. In specific embodiments, the small molecules comprise 3- pentadecylphenol (PDP).

[0067] For example, the BCP can be polystyrene-WocL-poly(4-vinyl pyridine) (PS-A-P4VP). The BCP-based supramolecules can be PS- / i-P4VP(PDP)i. which contains PDP bound to pyridine side chains of the PS-A-P4VP via hydrogen bonding. The PS-6-P4VP includes two random-coil blocks and forms spherical microdomains of P4VP surrounded by a matrix of PS. Without being bound to a particular theory, when the PDP hydrogen bonds to the pyridine rings, the P4VP block is stretched out to form a rigid comb-block. This structure occupies significantly more volume, and so the supramolecule forms lamellar, rather than spherical, microdomains. By binding to the pyridine rings, the PDP forms a periodic lamellar structure as well, resulting in a lamellae-within-lamellae hierarchical morphology.

[0068] The small molecule PDP adds mobility to the system by diluting BCP entanglements, and increases the volume of the P4VP blocks. PDP has a solubility parameter between that of the BCP blocks and the NP ligands, so free PDP can relax the unfavorable interface between blocks or around NPs, and stabilize morphologies with large surface areas. Free PDP can also redistribute over relatively large distances to accommodate constraints. The intermediate strength of the hydrogen bonds gives the PDP some freedom to rearrange. Much of the self-regulating behavior of the nanocomposite material system can be attributed to the small molecule.

[0069] The nanoparticles can be inorganic molecules, such as metal oxide nanoparticles [e.g., zirconium oxide (ZrC )], noble metal nanoparticles (e.g., gold), or silica nanoparticles. In some embodiments, the nanoparticles is about 3 nm to about 50 nm in size, about 3 nm to about 9 nm in size, or about 6 nm in size. In specific embodiments, the nanoparticles comprise ZrC which is about 6 nm in size.

[0070] Table 1 provides example formulations and compositions of nanocomposite materials provided herein. These nanocomposite materials include BCPs with molecular weights of 134 kDa, 455 kDa, and 557 kDa. They form lamellar or cylindrical microdomains with periodicities ranging from about 60 nm (Sl / NP) to about 170 nm (S3 / NP). The PDP molecules are dispersed in both the PS-rich and the P4VP(PDP)-rich microdomains; spatially resolved energy-dispersive X-ray spectroscopy (EDS) of S2 / NP with iodine-labelled small molecules (I-PDP) is shown in FIG. 3. The dispersed PDP molecules screen nonfavorable interactions between PS and P4VP(PDP) and are essential to realize entropy-driven phase behaviors such as formulation flexibility. S3 / NP blends based on 557-kDa PS-A-P4VP can accommodate up to 20 vol% of nanoparticles within parallel layers.

[0071] In the nanocomposite material provided herein, the nanoparticles can be about 3-20% volume (e.g., about 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20% volume), the small molecules can be about 10-25% volume (e.g., about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25% volume), and BCP-based supramolecules can be about 65-75% volume (e.g., about 65, 66, 67, 68, 69, 70, 71, 72, 83, 74, or 75% volume) of the nanocomposite material.

[0072] The nanoparticles, small molecules, and BCP-based supramolecules (collectively solutes) can be dissolved in a solvent and can self-assemble into multilayered nanosheets in the drying process. Solvent can be any solvent that dissolves the solute (i.e., small molecules and BCP-based supramolecules) and is suitable for producing the nanocomposite. For example, solvent can be chloroform, which dissolves PS and P4VP nearly equally well, and also dissolves PDP. Solvent can also be benzene, which has less X-ray absorption than chloroform. The solutes can be dissolved in the solvent to form a 1-20 volume % (e.g., 1-5, 5-10, 10-15, 15-20, or greater than 20 volume %) solution. The overlap concentration of a polymer solution scales as '1 8in good solvents and is estimated to be >20 volume % for solutes containing 134-kDa BCPs and about 2.7 volume % for solutes containing 455-kDa BCPs, respectively.

[0073] Each nanosheet of the nanocomposite material can be about 50 nm to about 410 nm thick, such as about 50-100, 50 -150, 50-200, 200-300, 300-410 nm thick, or about 150, 100, 125, 150, 200, 250, 300, 350, 400, or 410 nm thick.

[0074] The nanocomposite material can contain about 20 to about 100, about 20 to about 200, about 100 to about 200, or about 200 or greater number of nanosheets. A greater number of nanosheets can provide a greater functionality of the nanocomposite material, such as for use as a barrier material or an optical material.

[0075] The early microscopic structure determines the degree of long-range order (i.e., defect density) of the nanostructure. The step-like changes in the diffusion mode of the nanoparticles and in the system mobilities identify the processing window in which to program micro-first-nano-later growth. As shown in FIG. 4H, the long-range order is poor when solvent removal occurs at 23 vol% solute concentration, which is too dilute to drive the condensation of molecular aggregates despite high system mobility. With rapid solvent removal at 40 vol%, distinct nanosheets have formed, but the defect density is high and the aspect ratios of the nanosheets are less than 40. This suggests that nanostructure formation can compete with and disrupt microframework formation. The best long- range order is achieved by quenching the fdm at 28%, slightly below the concentration at which nanosheets have formed. The nanosheets are tens of micrometers in length with aspect ratios greater than 500. Thus, the long-range order, that is, the defect density, can be regulated by optimizing the organization of sheet-like aggregates before nanostructure formation.

[0076] Defect type also determines barrier performance because different defects have varied effects on transport pathways. The prevalence of different defect types is set by short-range diffusion during the last stages of assembly. Blends based on lower molecular weights, for example, SI, have more circular microdomains between nanosheets and sharply bent microdomains, which we have named ‘U-turn’ defects, are uncommon. These defect morphologies are results of local reorganization and show that the system is mobile enough to reorganize BCP-based supramolecules to release packing frustrations. However, for blends based on high-molecular-weight building blocks, for example, S2 / NP and S2, most defects are paired ends and U-turn types. Some nanosheets zigzag into several continuous U-turns (FIGs. 5A-5B). There is a substantial energy penalty associated with bending the nanosheets at such sharp angles. However, the entanglements of the long chains elevate the energy barrier for local reorganization and kinetically trap these defects after microframework formation. The U-turn defects can be annihilated by increasing the stiffness of the nanosheets, such as by adding nanoparticles or driving the system to lower solvent fractions, to further enhance the long- range order. Paired-end defects disconnect the transport pathway and are desirable for engineering barrier materials. Thus, the ability of the long -chain entanglements to decouple defect manipulation from nanostructure formation is advantageous for controlling the prevalence of different defect types.

[0077] The nanocomposite material provided herein can include 0.2 pm-2or less, 0. 1 pm-2or less, 0.09 pm-2or less, 0.08 pm-2or less, 0.07 pm-2or less, 0.06 pm-2or less, or 0.05 pm-2or less defect density. In specific embodiments, the nanocomposite material contains about 0.06 pm-2or less defect density, and about 98% efficiency in controlling the defect type.

[0078] The multilayered nanocomposite materials provided herein are competitive barrier materials with performance comparable — or superior — to current industry standards and offer notable advantages in their material chemistry and programmable life cycle. The nanocomposite materials provided herein have built-in recyclability and provide solutions to recycling issues associated with existing metallized and multilayered films. The long-chain entanglement provides mechanical robustness such that chemical crosslinks are not needed. They are amenable to cycles of assembly,disassembly and reassembly without compromising structure integrity, highlighting the advantages of bottom-up material synthesis (see embodiments in FIGs. 8A-8D).

[0079] The nanocomposite material provided herein can have an improved barrier function against a volatile organic compound (VOC), water, oxygen, and / or electron relative to a control material. In some embodiments, the nanocomposite material has VOC removal efficiency of 40% or more, water vapor transmission rate (WVTR) of 8 g nr2day' 'or less, dielectric breakdown strength of 500 MV / rn'1or more, maximum discharged energy density of 3 J cm'3or more, and / or encapsulant lifetime of 3 min pm1or more.

[0080] For example, when coated on porous Teflon membranes, 30-pm S2 / NP coatings reduce the permeation of common volatile organic compounds (VOCs) with a removal efficiency of 100 ± 0% for 2-butanone and hexaldehyde (kinetic diameter dk > 5.3 A), 96 ± 0% for acetaldehyde (dk = 5.0 A), 94 ± 9.2% for acetone (dk = 4.4 A) and 55 ± 4.2% for formaldehyde (dk = 3.7 A) (FIG. 7E). This performance is comparable with wet scrubbers based on electrochemical cells with a removal efficiency of 95% at a similar VOC concentration. A 30-pm S2 / NP coating on a 127-pm polyester film can substantially reduce its water-vapor transmission rate (WVTR) from 11.5 ± 5.7 g m2day1to 5.3 ± 0.6 g m2day '. with more consistent barrier performance over three weeks of testing (FIG. 7F).

[0081] With 98% efficiency in defect-type control, the nanocomposites with stacked nanosheets are also excellent barriers for electrons, making them high-performance dielectric materials for energy storage. S2 / NP films have an energy efficiency of 91.2% at 650 MV m1with a charge-discharge efficiency exceeding 90% and a discharged energy density of 6.2 J cm3(FIG. 7G). This performance is comparable with current industry benchmark dielectrics, including biaxially oriented polypropylene (BOPP) (FIG. 7G). The high dielectric breakdown strength of the nanocomposite film is another testament to the importance of their low defect density and high efficiency in defect-type control.

[0082] Organic electronics, including organic light-emitting diodes and photovoltaics, must be encapsulated to prevent degradation by oxygen and water vapor; irregular device topologies present a particular challenge. Calcium films rapidly oxidize under ambient conditions and their relative conductance is a convenient proxy for longer-term device degradation. Electrical calcium tests were used to compare the barrier properties of the S2 / NP nanocomposite with two standard ultraviolet (UV)-curable epoxies, DELO Katiobond LP655 and Ossila E132 (FIG. 7H). Despite substantial differences in the barrier thickness, their performances are comparable. A 50% relative conductance of the encapsulated calcium films was reached after 241 ± 27 min for DELO Katiobond LP655 (about 119 pm), 367 ± 53 min for Ossila E132 (about 218 pm) and 79 ± 11 min for S2 / NP (about 35 pm). When normalized by the film thickness, the S2 / NP barriers nearly double the time until a calcium film reaches 0% relative conductance. Thus, self-assembled nanosheets can lead to thinner and more flexible organic electronics and their built-in recyclability can contribute to better control over the life cycle of organic electronics.

[0083] The performance of a barrier material is set by its composition and structure: the layer composition and dimension, defect type and density, long-range order, mechanical properties and geometric conformability. Nanoparticles are instrumental to modulating defect types, achieving entropy-driven phase behaviors and improving barrier, dielectric and mechanical properties. Long- range order of the nanostructure and local defect control are essential to realize the benefits of functional nanomaterials. The ordering of nanocomposites also had a pronounced effect on their mechanical properties. Supramolecules formed by high-molecular-weight BCPs contributes to high performance of the nanocomposite materials provided herein. Contrary to the common belief that chain entanglements are detrimental to assembly kinetics, high-molecular-weight building blocks are advantageous and essential to realize programmable, rapid growth of nanosheets with long-range order and defect control. Excellent barrier performance relies on the thick nanosheets they assemble into.

[0084] The nanocomposite material can have hierarchically ordered structure. For example, the nanocomposite material can have alternating layers of conductive (or semiconductive) nanoparticlerich regions and nonconductive nanoparticle -poor regions. The nanocomposite material can have alternating layers of a nanosheet of nanoparticles (or a nanosheet rich in nanoparticles) and a nanosheet of BCP-based supramolecules (or a nanosheet rich in BCP -based supramolecules). Where nanosheets of (or nanosheets rich in) nanoparticles and nanosheets of (or nanosheets rich in) BCP- based supramolecules are present in the nanocomposite material, each nanosheet of nanoparticles can be about 50 nm to 410 run thick, or 50 nm to 150 run thick, and wherein each nanosheet of BCP-based supramolecules can be 50 nm to 410 nm thick, or about 50 nm to 150 nm thick. Each nanosheet of nanoparticles can be about as thick as each nanosheet of BCP-based supramolecules. Alternatively, each nanosheet of nanoparticles can be thicker than each nanosheet of BCP-based supramolecules. The nanocomposite material can also have regions rich in one of the two polymers of the BCP, and regions rich in the other polymer of the BCP, e.g., PS-rich regions and P4VP(PDP)-rich regions in the nanocomposite material comprising PPS-A-P4VP.

[0085] The nanocomposite materials provided herein have wide applicability as coating or barrier materials. For example, substrates (e.g., about 10 cm to 15 cm in length and width, or smaller or larger) can be coated by the nanocomposite materials provided herein. Surfaces of any texture (rough or smooth) can be coated by the nanocomposite materials provided herein. The coatings can be used as barriers against VOC, water vapor, and oxygen, and as electric insulators and dielectric capacitators. The coating compositions provided herein can readily be applied as a dielectric fdm, or as electronics packaging, and can be incorporated into consumer-facing packaging (e.g., food wrappers). Advantages of the coating compositions provided herein includes barrier function relative to its thickness due to its large number of layers, offering competitive barrier function relative to much thicker barrier layers made of fewer layers. Further, the coating compositions provided herein can have improved recyclability because the materials can be dissolved and recast as a single waste stream. The mechanical stability of the coating compositions provided herein is derived from physicalchain entanglements rather than chemical crosslinks. The coating compositions provided herein are fabricated via self-assembly process, without chemical transformations, and is completely reversible. The nanocomposite materials provided herein can also be used for purposes other than as coating or barrier materials, such as for optical materials, as further provided herein.B. Nanocomposite Materials with Gradient Structures

[0086] Spatial gradients are a valuable element in nanoscale design: they are frequently employed to improve the mechanical, optical, or stimulus response properties of biological nanostructures. Provided herein are nanocomposite materials with functional gradient motifs generated by selfassembly. Self-assembly is typically associated with uniform or periodic nanostructures, but here, a single BCP -based supramolecular nanocomposite can be used to produce a rich variety of ordered multilayer structures. Between drop-cast fdms of the same nanocomposite solution, different drying routines can be used to achieve layer thicknesses from 72 to 400 nm. The nanocomposite materials provided herein can have pronounced gradients within many of the individual fdms, with < 175% increases in layer thickness observed from the fdms’ bottom to top interfaces.

[0087] Layered nanocomposites with gradient periodicity can be fabricated by modulating processing conditions and compositions, such as small molecule (e.g., PDP) concentration, unbonded and hydrogen-bonded small molecule ratios, BCP (e.g., PS-A-P4VP) molecular weight, and drying rate and conditions. Generally, slower drying rate and / or higher solute ratio in the solute / solvent mixture provides nanosheets that are thicker and appear redder in color. Further, small molecule mobility (chemical or cross-linking) can be modulated to obtain nanocomposite materials of morphology of interest. The nanocomposite materials provided herein, particularly nanocomposite materials with gradient layer thickness and property, have unique optical properties and can be used as optical materials such as light fdters, flat lenses, and zone plates.

[0088] The nanocomposite material can have the plurality of nanosheet with a gradient layer thickness, e.g., thinner layers toward the substrate-nanocomposite material interface and thicker layers away from the substrate. In some embodiments, the thickness of nanosheets in the nanocomposite material ranges from about 65 nm to about 135 nm (e.g., from about 72 nm to about 126 nm), from about 120 nm to about 280 nm (e.g., from about 151 nm to about 223 nm), from about 120 nm to about 250 nm (e.g., from about 127 nm to about 221 nm), or from about 120 nm to about 410 nm (e.g., from about 135 nm to about 370 nm).

[0089] For example, within a drying drop-cast film, the solute concentration is a function of both time and depth (FIG. 9A). Thus, at every time point until the film is fully dry, the solute and solvent fractions form a smooth gradient through the thickness of the film. Using a high-molecular-weight supramolecular nanocomposite blend, the characteristic layer width, f is varied by varying the film’s drying rate and duration. Nanocomposite films that were dried quickly have relatively small domain thicknesses, while slowly-dried films exhibit significantly larger f values (FIGs. 9B-9E). In addition to substantial differences between samples, pronounced f gradients are present within individualsamples. When dried over 3 days, nanosheets as thick as 280-340 nm can form (FIG. 12K). Every sample shown in FIGs. 9B-9E has the same composition, film thickness, and initial concentration. The underlying mechanism of gradient multilayers involves a combination of entropic, enthalpic, and kinetic factors.C. Methods of Producing the Nanocomposite Materials

[0090] A method of producing a nanocomposite material provided herein can include contacting an initial blend of nanoparticles, small molecules, and block copolymer (BCP)-based supramolecules with a solvent to form a mixture, and drying the mixture to remove the solvent, forming via a selfassembly process the nanocomposite material comprising a plurality of nanosheets containing the nanoparticles, the small molecules, and the BCP-based supramolecules. The BCP-based supramolecules contains BCPs and small molecules.

[0091] The nanoparticles, small molecules, and BCP-based supramolecules (collectively solutes) can be dissolved in a solvent and can self-assemble into multilayered nanosheets in the drying process. Solvent can be any solvent that dissolves the solute (i.e., small molecules and BCP-based supramolecules) and is suitable for producing the nanocomposite. For example, solvent can be chloroform, which dissolves PS and P4VP nearly equally well, and also dissolves PDP. Solvent can also be benzene, which dissolves the solutes and has less X-ray absorption than chloroform, and thus is suitable for SAXS and XPCS studies. The solutes can be dissolved in the solvent to form a 1-20 volume % (e.g., 1-5, 5-10, 10-15, 15-20, or greater than 20 volume %) solution. The overlap concentration of a polymer solution scales as '1 8in good solvents and is estimated to be >20 volume % for solutes containing 134-kDa BCPs and about 2.7 volume % for solutes containing 455-kDa BCPs, respectively.

[0092] Contacting the initial blend of nanoparticles, small molecules, and block copolymer (BCP)- based supramolecules with the solvent can include contacting the initial blend of nanoparticles, small molecules, and BCP-based supramolecules with the solvent that is about 95% to about 100% volume, or about 97.5% volume of the mixture (i.e., the initial blend is about 5% or less, or about 2.5% volume of the mixture).

[0093] The drying process can include removing the solvent to initiate the self-assembly process. The solute can start aggregating in about 3-10 (such as 5) volume % solutions (i.e., the solvent is 90- 97 volume %, such as 95 volume %). The self-assembly process can occur when a volume percent of solvent in the mixture decreases, and the solute volume % increases. For example, the self-assembly can occur when the solvent volume % is about 70% to about 80% or less (i.e., the solute volume % is about 20% to about 30% or more). For example, as shown in FIG. 4H, at 23 volume %, 28 volume % and 40 volume % of solutes, nanostructures can form. However, the long-range order is poor when solvent removal occurs at 23 vol%. The solute concentration is too dilute to drive the condensation of molecular aggregates despite high system mobility. With rapid solvent removal at 40 vol%, distinct nanosheets have formed, but the defect density is high and the aspect ratios of the nanosheets are lessthan 40. This suggests that nanostructure formation can compete with and disrupt microframework formation. The best long-range order can be achieved by quenching the fdm at 28%, slightly below the concentration at which nanosheets have formed.

[0094] The drying process can take from about 20 minutes to about 3 days (e.g., 20 minutes, 30 minutes, 60 minutes, 90 minutes, 2 hours, 4 hours, 6 hours, 8 hours, 10 hours, 12 hours, 1 day, 2 days, 3 days), and can be adjusted based on the speed of process and nanocomposite materials desired. When the nanocomposite materials are dried too quickly, microdomains may be disordered and microframework may not form (e.g., FIG. 6E).

[0095] The method can further include adjusting the drying rate, mixture depth, and / or solute / solvent ratio in the mixture to adjust thickness and / or color of the plurality of nanosheets. Generally, slower drying rate or a higher solute ratio in the mixture can generate a thicker and / or redder colored nanosheet. The methods provided herein can produce nanocomposite materials with gradient multilayers by adjusting the parameters and using the self-assembly mechanism.

[0096] The mixture can be drop-cast onto a substrate before drying the mixture. The substrate can be any material with any surface condition, including a solid, a lens, a membrane, a fdm, or a wafer made of Teflon, polyester, silicon, or glass.

[0097] The BCP -based supramolecules used in the method comprise a BCP and small molecules bound to the BCP via non-co valent bonds.

[0098] The BCP can comprise a molecular weight of about 130 kDa to about 600 kDa, such as about 130 kDa, about 200 kDa, about 300 kDa, about 400 kDa, about 450 kDa, about 500 kDa, about 560 kDa, or about 600 kDa. As specific examples, the BCPs can have molecular weights of 134 kDa, 455 kDa, and 557 kDa, as listed in Table 1. In specific embodiments, the BCP is a high molecular weight polymer (e.g., having a molecular weight of about 100, 200, 300, 400, or 500 kDa or greater).

[0099] The BCP -based supramolecules can each comprise a BCP and small molecules bound to the BCP via non-covalent bonds. For example, BCP-based supramolecules can be constructed by non- covalently attaching small molecules to polymer side chains.

[0100] The small molecules can be organic molecules. Small molecules can contain a molar mass of about 50 g / mol to about 1500 g / mol. In specific embodiments, the small molecules comprise 3- pentadecylphenol (PDP).

[0101] For example, the BCP can be polystyrene-Woc -poly(4-vinyl pyridine) (PS-A-P4VP). The BCP-based supramolecules can be PS- / i-P4VP(PDP)i. which contains PDP bound to pyridine side chains of the PS-6-P4VP via hydrogen bonding. The PS-6-P4VP includes two random-coil blocks and forms spherical microdomains of P4VP surrounded by a matrix of PS. Without being bound to a particular theory, when the PDP hydrogen bonds to the pyridine rings, the P4VP block is stretched out to form a rigid comb-block. This structure occupies significantly more volume, and so the supramolecule forms lamellar, rather than spherical, microdomains. By binding to the pyridine rings,the PDP forms a periodic lamellar structure as well, resulting in a lamellae-within-lamellae hierarchical morphology.

[0102] The nanoparticles can be inorganic molecules, such as metal oxide nanoparticles [e.g., zirconium oxide (ZrC )], noble metal nanoparticles (e.g., gold), or silica nanoparticles. In some embodiments, the nanoparticles is about 3 nm to about 50 nm in size, about 3 nm to about 9 run in size, or about 6 nm in size. In specific embodiments, the nanoparticles comprise ZrCE. which is about 6 nm in size.

[0103] Table 1 provides example formulations and compositions of the initial blend provided herein. The PDP molecules are dispersed in both the PS-rich and the P4VP(PDP)-rich microdomains. The dispersed PDP molecules screen nonfavorable interactions between PS and P4VP(PDP) realize entropy-driven phase behaviors such as formulation flexibility. S3 / NP blends based on 557-kDa PS-A- P4VP can accommodate up to 20 vol% of nanoparticles within parallel layers.

[0104] In the methods provided herein, the nanoparticles can be about 3-20% volume (e.g., about 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, or 20% volume), the small molecules can be about 10-25% volume (e.g., about 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, or 25% volume), and BCP-based supramolecules can be about 65-75% volume (e.g., about 65, 66, 67, 68, 69, 70, 71, 72, 83, 74, or 75% volume) of the initial blend of the nanoparticles, small molecules, and BCP-based supramolecules.

[0105] The methods can involve drying the mixture to remove the solvent, forming via a selfassembly process a material comprising alternating layers of conductive (or semiconductive) nanoparticle -rich regions and nonconductive nanoparticle-poor regions. The methods can produce a nanocomposite material having alternating layers of a nanosheet of nanoparticles (or a nanosheet rich in nanoparticles) and a nanosheet of BCP-based supramolecules (or a nanosheet rich in BCP-based supramolecules). Where nanosheets of (or nanosheets rich in) nanoparticles and nanosheets of (or nanosheets rich in) BCP-based supramolecules are present in the nanocomposite material, each nanosheet of nanoparticles can be about 50 nm to 410 nm thick, or 50 nm to 150 nm thick, and wherein each nanosheet of BCP-based supramolecules can be 50 nm to 410 nm thick, or about 50 nm to 150 nm thick. Each nanosheet of nanoparticles can be about as thick as each nanosheet of BCP- based supramolecules. Alternatively, each nanosheet of nanoparticles can be thicker than each nanosheet of BCP-based supramolecules. The methods can also produce a nanocomposite material having regions rich in one of the two polymers of the BCP, and regions rich in the other polymer of the BCP, e.g., PS-rich regions and P4VP(PDP)-rich regions in the nanocomposite material comprising PPS-6-P4VP.

[0106] Also provided is a nanocomposite material produced by the method provided herein. The nanocomposite material can have about 20 to about 100, about 20 to about 200, or about 200 or greater number of nanosheets, with each nanosheet about 50 nm to about 410 nm thick, such as about 50-100, 50 -150, 50-200, 200-300, 300-410 nm thick, or about 150, 100, 125, 150, 200, 250, 300, 350,400, or 410 nm thick. The nanocomposite material can have about 0.06 pm-2or less defect density, and about 98% efficiency in controlling the defect type. The nanocomposite material can have improved barrier function against a volatile organic compound (VOC), water, oxygen, and / or electron relative to a control material, and / or any other characteristics provided herein.

[0107] Also provided herein is a barrier material containing the nanocomposite material produced by the method provided herein. The nanocomposite materials produced by the methods provided herein can be used as barrier materials, optic materials, or coating materials in a variety of applications, including but not limited to, as a volatile organic compound barrier, a water barrier, an oxygen barrier, an electron barrier, a dielectric capacitator, an optical material (e.g., light filters, flat lens, zone plates), and / or a packaging for consumer products (e.g., as a food wrapper).EXAMPLESExample 1: Functional composites by programming entropy-driven nanosheet growth

[0108] The current challenges in fabricating 2D nanosheets were addressed by introducing a new nanomaterial design with two elements: (1) the ability of entropy-driven assemblies is used to accommodate variations in reactant composition and pair interactions during processing and integration and (2) the system mobility is matched with the necessary diffusion of the building blocks to form targeted structures. As shown in FIG. IB, sequential growth follows a nano-to-micro growth process, in which the smallest structure features form when the system mobility is the highest and vice versa. The growth pathway provided herein proceeds in a reversed, micro-first-nano-later sequence (FIG. 1C): microstructures are defined first when the system has the highest mobility, followed by nanostructure formation through local organization of building blocks. Entropy-driven phase behavior helps realize this large-to-small growth pathway. It allows the system to form microscopic aggregates in dilute solutions when the system is mobile enough to organize large-scale structures.Thermodynamically, the entropy-driven phase behaviors seen in high-entropy alloys offer formulation flexibility while maintaining structure fidelity. Thus, target nanostructures can form using many combinations of locally available components when the system mobility is low. Guided by this new design, coatings composed of more than 200 stacked nanosheets (125 nm in sheet thickness) with a defect density below 0.056 pm2and approximately 98% efficiency in defect control were fabricated. The coatings exhibit high-performance barrier properties against volatile organic compounds, water and oxygen for use as packaging, as well as against electrons for use as dielectric capacitors.System selection

[0109] The entropy-driven assembly approach was tested using complex blends that exhibit entropy-driven self-assembly. The specific blends are composed of 6-nm zirconium oxide (ZrO?) nanoparticles, 3 -pentadecylphenol (PDP) small molecules, and BCP -based supramolecules (abbreviated PS- / ?-P4VP(PDP)i) that are constructed by hydrogen-bonding PDP to the pyridine side chains of polystyrene-Woc -poly(vinyl pyridine) (PS-6-P4VP). As shown in FIGs. 2A-2I, theseblends are self-assembling with formulation flexibility and structure fidelity similar to what is observed in high-entropy alloys. They form nanostructures when the effective interactions between PS-rich and P4VP(PDP)-rich microdomains are close to or equal to zero. Thus, components can readily diffuse across interfaces, even when the system mobility is low. The P4VP chemistry is beneficial to optimizing the substrate adhesion of the coating.

[0110] With an ultimate goal of engineering technologically relevant coating materials, high- molecular-weight BCP-based supramolecules were chosen to access the thick nanosheets needed for mechanical robustness and good barrier resistance. The formulations of complex blends, based on BCPs with molecular weights of 134 kDa, 455 kDa, and 557 kDa, are listed in Table 1. They form lamellar or cylindrical microdomains with periodicities ranging from about 60 nm (Sl / NP) to about 170 nm (S3 / NP). The PDP molecules are dispersed in both the PS-rich and the P4VP(PDP)-rich microdomains; spatially resolved energy-dispersive X-ray spectroscopy (EDS) of S2 / NP with iodine- labelled small molecules (I-PDP) is shown in FIG. 3. The dispersed PDP molecules screen nonfavorable interactions between PS and P4VP(PDP) and are essential to realize entropy-driven phase behaviors such as formulation flexibility. The proprietary ligand chemistry of the ZrO2 nanoparticles is unknown, yet S3 / NP blends based on 557-kDa PS-6-P4VP can accommodate up to 20 vol% of nanoparticles within parallel layers.

[0111] The long-polymer-chain entanglements serve several roles: they program the kinetic pathway to match the mobility of the system with its stages of structure evolution and modulate the local defect morphology. The critical overlap concentration of a polymer solution scales as W1 8in good solvents and is estimated to be >20 vol% for SI and about 2.7 vol% for S2 based on 134-kDa and 455-kDa BCPs, respectively. By using high-molecular-weight building blocks, the blend forms molecular aggregates in a more dilute solution. This provides sufficient system mobility to organize molecular aggregates into extended microframeworks for subsequent nanostructure formation. The long-chain entanglements increase the kinetic stability and integrity of the aggregates during subsequent growth and organization. Long-chain entanglement can slow down local reorganization at the defect sites and, thus, maintain end-to-end pair-defect morphology.Table 1. Formulation and compositions of the blends studiedThe supramolecule notation includes the molecular weight of the PS and P4VP blocks. PDP molecules are expected to hydrogen-bond to 4VP monomers at a 1: 1 ratio, denoted P4VP(1).Nanocomposite formation: kinetic pathway

[0112] To program nanosheet growth, Sl / NP, S2 / NP and S3 / NP blends were studied to identify the solution concentrations that form molecular aggregates and lamellar microdomains / nanosheets and quantified the system mobility at nano and micro scales. Using small-angle neutron scattering (SANS) and small-angle X-ray scattering (SAXS), it was found that S2 / NP forms molecular aggregates with specific nanoparticle partitions in the P4VP(PDP)-rich region forming at approximately 10 vol% and well-defined lamellae at a solute concentration of 30 vol%. FIG. 4A shows the SANS profiles of S2 / NP at solute concentrations of 5 vol% and 10 vol%. Guinier-Porod analysis shows that, at 5 vol%, S2 / NP forms fuzzy molecular aggregates, about 100 nm in size and without a preferential partition of nanoparticles. At 10 vol%, the molecular aggregates become better defined, with sharper aggregate / solvent interfaces, and nanoparticles preferentially reside in the P4VP(PDP)-rich regions. However, lamellar microdomains have not yet assembled. Ultra-small-angle neutron scattering (USANS) suggests the presence of larger assemblies with an Rg of 453 nm, estimated from a slope transition at q = 3.8 x I O3nm1(FIG. 4B). Randomly arranged aggregates were also seen in liquid-cell transmission electron microscopy (TEM) studies (FIG. 4B, inset).

[0113] The inhomogeneous distribution of nanoparticles in 10 vol% S2 / NP was confirmed using SAXS, which shows a broad correlation hole with a characteristic size of about 114 nm (q = 0.055 nm-1). This is consistent with its ultra-small -angle X-ray scattering (USAXS) profile in FIG. 4C. The S3 / NP blend is based on 557-kDa BCPs and form molecular aggregates at a much lower solute concentration than S2 / NP. This is indeed the case: the USAXS profile of S3 / NP at a 10 vol% solute concentration shows large-scale assemblies evidenced from strong scattering in the low-q region and emerging nanostructures described by a scattering peak at q = 0.043 nm-1 (FIG. 4C). In situ SAXS studies showed that well-ordered lamellar microdomains with a periodicity of 126 nm and a Scherrer grain size of about 1.73 pm form almost immediately as the S2 / NP solution concentration approaches roughly 30 vol% (FIG. 4D). Aggregates can rapidly transform into nanosheets. Thus, microscopically arranged molecular aggregates can template nanosheet growth and modulate the long-range order of the nanocomposite. For them to do so, however, requires substantial system mobility.

[0114] The S2 / NP system mobility was quantified using X-ray photon correlation spectroscopy (XPCS) to examine the spatial distribution of the ZrO? nanoparticles throughout an in situ drying process (FIG. 4E). On the basis of fitting the Kohlrausch exponent y, nanoparticle diffusion changes from subdiffusive (y ~ 3.5) to diffusive (y ~ 2) motion as the solute concentration increases from 10 vol%. This is consistent with the SANS results and suggests that nanoparticles leave the meshes of entangled PS to selectively enrich the P4VP(PDP)-rich region. The nanoparticle diffusivity was further quantified at the nano and micro scales by determining the relaxation times at two length scales: rsat q = 0.3 nm1and n at q = 0.03 nm1(FIG. 4F). When the molecular aggregates form around 10 vol%, the blend has good mobility for both nanoscopic and microscopic diffusion, with rsapproximately 100 times faster ( 10 s) than n ( I O3s). However, when nanosheets form (roughly 30 vol%), the relaxation times increase sharply (n ~ 1,000 s and rs~ 100 s) and are proportional to thediffusion length scales they describe. The system mobility is too limited to alter the templated microstructures. The subsequent nanostructure formation must rely on short-range diffusion to locally organize different building blocks.

[0115] The generality of this assembly process was assessed using the S lcy1 / NP blend, which forms cylindrical microdomains with a periodicity of approximately 80 nm. The drying condition to process Slcyl / NP fdms was modulated to vary the incubation time (At) between the formation of molecular aggregates and the nanostructure formation. In situ grazing transmission small-angle X-ray scattering (GTSAXS) was used to characterize the structure evolution throughout the full solution / fdm thickness over an estimated beam-path length of about 1.5 mm. When the At was sufficiently long (about 11 min for this blend), several orders of diffraction peaks appeared rapidly, confirming that mobility-based nanostructure growth can lead to a high degree of long-range ordering in morphologies other than lamellae (FIG. 4G).Long-range order and defect optimization

[0116] The early microscopic structure determines the degree of long-range order of the nanostructure. The step-like changes in the diffusion mode of the nanoparticles and in the system mobilities identify the processing window in which to program micro-first-nano-later growth. The microscopic structure determines the degree of long-range order achieved by the nanostructure. Rapid solvent removal was used to kinetically trap the nanocomposite films at specific solute concentrations selected from the scattering results. Representative cross-sectional TEM images of S2 / NP films quenched at 23 vol%, 28 vol% and 40 vol% are shown in FIG. 4H. For all samples, nanostructures have clearly formed, despite the rapid solvent removal. This again confirms that nanostructure formation is not the rate-limiting step to hierarchically grow nanosheets. The long-range order is poor when solvent removal occurs at 23 vol%. The solute concentration is too dilute to drive the condensation of molecular aggregates despite high system mobility. With rapid solvent removal at 40 vol%, distinct nanosheets have formed, but the defect density is high and the aspect ratios of the nanosheets are less than 40. This suggests that nanostructure formation can compete with and disrupt microframework formation. The best long-range order is achieved by quenching the film at 28%, slightly below the concentration at which nanosheets have formed. The nanosheets are tens of micrometers in length with aspect ratios greater than 500. Thus, the long-range order, that is, the defect density, can be regulated by optimizing the organization of sheet-like aggregates before nanostructure formation.

[0117] Defect type also determines barrier performance because different defects have varied effects on transport pathways. The prevalence of different defect types is set by short-range diffusion during the last stages of assembly. Full defect densities are provided in Table 2. Blends based on lower molecular weights, for example, SI, have more circular microdomains between nanosheets and sharply bent microdomains, which we have named ‘U-turn’ defects, are uncommon. These defect morphologies are results of local reorganization and show that the system is mobile enough toreorganize BCP-based supramolecules to release packing frustrations. However, for blends based on high-molecular-weight building blocks, for example, S2 / NP and S2, most defects are paired ends and U-turn types. Some nanosheets zigzag into several continuous U-turns (FIGs. 5A-5B). There is a substantial energy penalty associated with bending the nanosheets at such sharp angles. However, the entanglements of the long chains elevate the energy barrier for local reorganization and kinetically trap these defects after microframework formation. The U-turn defects can be annihilated by increasing the stiffness of the nanosheets, such as by adding nanoparticles or driving the system to lower solvent fractions, to further enhance the long-range order. Paired-end defects disconnect the transport pathway and are desirable for engineering barrier materials. Thus, the ability of the long- chain entanglements to decouple defect manipulation from nanostructure formation is advantageous for controlling the prevalence of different defect types.Table 2. Full defect analysis output for thick and thin filmsComposite images were divided into 5 sub-images of approximately equal size. The defect densities of each subimage were calculated separately, and the standard deviation of the densities were calculated.Programmed composite coating fabrication

[0118] Macroscopic nanocomposite coatings were fabricated on commercial membranes by tuning the evaporation of S2 / NP solutions to maximize the time spent between 23 vol% and 28 vol%, with rapid drying afterwards. FIGs. 6A-6B shows a cross-sectional TEM image of a S2 / NP film of around 35 pm in thickness. The film includes more than 200 parallel lamellae with a periodicity of 127 nm. Most nanosheets are continuous within and beyond the 90-pm field of view. A similar degree of long- range order extends in other regions of the film. Within the roughly 2,660 pm 2 imaged area, there were only 149 defects (FIG. 6C). Owing to a lack of reported defect densities for stacked nanosheets, the defect densities of the 60-nm-thick cross-sections were compared with those of BCP thin films (FIG. 6D). The S2 / NP defect density of 0.056 pm2is a fraction of densities obtained after multistep annealing treatments (3.5 pm2) or topography-directed self-assembly (0.267 pm2).

[0119] Nearly all the defects are paired ends (N = 146 out of 149, about 98%); the remaining defects are paired U-turns (N= 2) and a single junction (N= 1). Nanoparticles affect the long-range order and defect densities that, in turn, contribute to the properties of the coatings. Nanoparticle incorporation substantially increases the stiffness and bending modulus of the layers. They lead to straight nanosheets with high aspect ratios, low defect density and bias the defect-type distribution away from U-turns and junctions. Kinetic control can more than compensate for the increased entanglement of higher-molecular-weight supramolecules. When the incubation time At was reduced, only poorly ordered Sl / NP and S2 / NP films were observed; sufficiently long At led to highly ordered S3 / NP films with a periodicity of 174 nm and nanoparticle loading of 20 vol% (FIGs. 6E-6F).

[0120] When engineered at the system level, these nanocomposite films indeed satisfy numerous requirements as functional barrier coatings. With their long-range order and high-molecular-weight building blocks, S2 / NP films are flexible and mechanically robust; vibrant structural color is an added bonus of their relatively large feature sizes. They have an elastic modulus of 512 ± 122 MPa and a hardness of 13.6 ± 3.3 MPa, measured using nanoindentation. Owing to their entropy-driven phase behavior, stacked nanosheets form on different substrates despite variations in substrate chemistries (silicon, glass, polyester and Teflon) and roughness and shape irregularity (FIGs. 2A-2I). Cyclic stretching and buckling tests (N= 600) were performed on S2 / NP-coated polyester substrates (127 pm thickness, McMaster-Carr) and the coatings retained their integrity with no delamination or crack formation.High-performance nanocomposite barriers

[0121] Essential to product preservation and longevity, barrier materials are a central pillar of sustainability. The multilayered nanocomposite coatings are competitive barrier materials with performance comparable — or superior — to current industry standards and offer notable advantages in their material chemistry and programmable life cycle. Within each nanosheet of a S2 / NP film, the nanoparticle -rich region is about 70 nm thick and contains 10-15 layers of densely packed ZrCf nanoparticles, reminiscent of a miniaturized metallized film (FIG. 7A). However, these compositecoatings have built-in recyclability and provide solutions to recycling issues associated with existing metallized and multilayered films. The long-chain entanglement provides mechanical robustness such that chemical crosslinks are not needed. They are amenable to cycles of assembly, disassembly and reassembly without compromising structure integrity, highlighting the advantages of bottom -up material synthesis (FIGs. 8A-8D).

[0122] When coated on porous Teflon membranes, 30-pm S2 / NP coatings reduce the permeation of common volatile organic compounds (VOCs) with a removal efficiency of 100 ± 0% for 2-butanone and hexaldehyde (kinetic diameter dt> 5.3 A), 96 ± 0% for acetaldehyde (dt= 5.0 A), 94 ± 9.2% for acetone (dt= 4.4 A) and 55 ± 4.2% for formaldehyde (dt= 3.1 A) (FIG. 7E). This performance is comparable with wet scrubbers based on electrochemical cells with a removal efficiency of 95% at a similar VOC concentration. The barrier performance of the composite coating was tested for watervapor transmission as a substitute for multilayered packaging films. A 30-pm S2 / NP coating on a 127-pm polyester film can substantially reduce its water-vapor transmission rate (WVTR) from 11.5 ± 5.7 g m2day1to 5.3 ± 0.6 g m2day with more consistent barrier performance over three weeks of testing (FIG. 7F).

[0123] With 98% efficiency in defect-type control, the nanocomposites with stacked nanosheets are also excellent barriers for electrons, making them high-performance dielectric materials for energy storage. S2 / NP films have an energy efficiency of 91.2% at 650 MV m1with a charge-discharge efficiency exceeding 90% and a discharged energy density of 6.2 J cm3(FIG. 7G). This performance is comparable with current industry benchmark dielectrics, including biaxially oriented polypropylene (BOPP) (FIG. 7G). The high dielectric breakdown strength of the nanocomposite film is another testament to the importance of their low defect density and high efficiency in defect-type control.

[0124] Organic electronics, including organic light-emitting diodes and photovoltaics, must be encapsulated to prevent degradation by oxygen and water vapor; irregular device topologies present a particular challenge. Calcium films rapidly oxidize under ambient conditions and their relative conductance is a convenient proxy for longer-term device degradation. Electrical calcium tests were used to compare the barrier properties of the S2 / NP nanocomposite with two standard ultraviolet (UV)-curable epoxies, DELO Katiobond LP655 and Ossila E132 (FIG. 7H). Despite substantial differences in the barrier thickness, their performances are comparable. A 50% relative conductance of the encapsulated calcium films was reached after 241 ± 27 min for DELO Katiobond LP655 (about 119 pm), 367 ± 53 min for Ossila E132 (about 218 pm) and 79 ± 11 min for S2 / NP (about 35 pm). When normalized by the film thickness, the S2 / NP barriers nearly double the time until a calcium film reaches 0% relative conductance. Thus, self-assembled nanosheets can lead to thinner and more flexible organic electronics and their built-in recyclability can contribute to better control over the life cycle of organic electronics.

[0125] Systematic control studies confirm the importance of holistic nanomaterial design to achieve technologically relevant nanomaterials (FIGs. 7E-7H). The performance of a barrier material is set by its composition and every aspect of its structure: the layer composition and dimension, defect type anddensity, long-range order, mechanical properties and geometric conformability. Nanoparticles are instrumental to modulating defect types, achieving entropy-driven phase behaviors and improving barrier, dielectric and mechanical properties. Long-range order of the nanostructure and local defect control are essential to realize the benefits of functional nanomaterials. Poorly ordered S2 / NP composites, denoted S2dls / NP, exhibited a greater than 30% reduction in discharged energy density, from 6.2 to 4.3 J cm-3, and cannot serve as effective water-barrier coatings. The ordering of nanocomposites also had a pronounced effect on their mechanical properties. Poorly ordered S2dls / NP composites had an elastic modulus of 303 ± 129 MPa, 60% of the ordered value, and a hardness of 1.4 ± 1.4 MPa, only about 10% of the ordered value. Supramolecules formed by high-molecular-weight BCPs are crucial for high performance across every application tested in this study. Contrary to the common belief that chain entanglements are detrimental to assembly kinetics, high-molecular-weight building blocks are advantageous and essential to realize programmable, rapid growth of nanosheets with long-range order and defect control. Excellent barrier performance relies on the thick nanosheets they assemble into. When the nanosheets are only 60 nm in thickness, the barrier efficiency of Sl / NP dropped to 20-36% for all VOCs and to <10% for water, and the dielectric breakdown strength dropped from 637 to 469 MV m1with a >50% reduction in the maximum discharged energy density.Summary

[0126] The successful transformation of nanosheets into high-performance barrier materials highlights the importance and necessity of engineering nanomaterials at the system level. The results provided herein confirm the feasibility of converting the limitations in previous designs into unique advantages, creating nanomaterials that satisfy multifaceted requirements. This Example demonstrates that properly engineered nanomaterials are inherently multifunctional and, if designed thoughtfully, will ultimately harness the power of nanoscience to advance technologies.Materials and methods

[0127] Materials. Poly(styrcnc)- / i-poly(4-vinyl pyridine) was purchased from Polymer Source, Inc. (polydispersity index = 1. 1-1.2). 3-w-Pcntadccylphcnol (90-95% purity) was purchased from Acros Organics. Chloroform was purchased from Fisher Scientific and no HC1 was detected using NMR. Deuterated chloroform was purchased from Cambridge Isotope Laboratories. Zirconium dioxide nanoparticles dispersed in toluene (6 ± 2 nm) were purchased from Pixelligent. All materials were used as received, without further purification. In the following methods, the block copolymer is abbreviated PS-6-P4VP and the small molecule is abbreviated PDP. The supramolecule is abbreviated PS- / i-P4VP(PDP) to denote hydrogen bonding between the PDP and 4VP monomers. PDP is added in excess of the possible bonding sites, such that there is more than one PDP molecule for every 4VP monomer. Ratios for each blends are provided in Table 1.

[0128] Sample solution preparation. PS-6-P4VP and PDP powders were dissolved in chloroform to form a 25-mg-ml i (2.5 vol%) supramolecule solution. The solution was stirred overnight. Forsamples that include particles, a separately prepared nanoparticle suspension (25 mg ml ZrCE nanoparticles in chloroform) was added to the supramolecule solution and mixed by means of pipette pumping. For the SANS and USANS studies, the same preparation was performed with deuterated chloroform. For the SAXS and XPCS studies, the same preparation was performed with benzene owing to the high X-ray absorption of chloroform. Cross-sectional TEM imaging confirmed that the self-assembly pathway was consistent in benzene and in chloroform.

[0129] Drop-cast film sample preparation. For each drop-cast film, a 50-pl droplet of the 2.5- vol% solution was deposited on a l.S-crmsquare-shaped silicon substrate. To slow the drying process, the substrate was sealed within a capped 125 -ml glass jar, along with a 70-pl reservoir of pure solvent. The solution was left to dry for a predetermined amount of time (20, 30, 60 or 90 min). At the end of the drying time, the jar was opened and the substrate was quickly removed from the jar. Any remaining solvent evaporated within approximately 3 s, effectively ‘freezing’ the microstructure of the nanocomposite.

[0130] A white-light interferometer (Filmetrics F20) was used to measure the thickness of the film as a function of its drying time. At the beginning of the drying process, the thickness of the film is outside the measurement range of the interferometer. These thickness values were estimated by interpolating between the known initial film thickness (calculated from the solvent volume and substrate area) and an exponential decay fit of the later drying data. Thickness values were converted into solvent or solute fractions to compare results across different experiments.

[0131] Bulk sample preparation. To prepare the bulk samples, 1 ml of the 2.5-vol% polymer solution was dried in a 1-ml Teflon beaker at room temperature. The beaker was not sealed or covered, so solvent was allowed to evaporate freely. Because of the larger volume of solvent, the sample was left to dry overnight. Once dried, the nanocomposite was peeled from the Teflon beaker using tweezers. To prepare intentionally disordered samples, a jet of N2 was directed across the opening of the beaker. This sped the drying process to about 30 min.

[0132] Static solution SANS and USANS experiments. The EQ-SANS instrument of the Spallation Neutron Source of Oak Ridge National Laboratory was used for the SANS experiments47. The temperatures of the samples, which were contained in cylindrical quartz cuvettes, were maintained at 25 ± 0.1 °C. Each sample was measured using three settings of the sample-to-detector distance and minimum wavelength: 9 m / 15 A, 4 m / 10 A and 2.5 m / 2.5 A. Collectively, these three configurations span a range of momentum transfers, q, of 0.002 A1< q < 0.7 A1. The data from the samples and the solvent were corrected for wavelength-dependent transmission, incident flux, detector sensitivity, geometric effects and the signal from the empty quartz cell before being azimuthally averaged and binned into ID I(q) versus q using the standard procedures implemented in the drtsans software48. During data reduction, the data were scaled into absolute intensities of 1 cm1using a calibrated porous silica standard49. Then, the data from the three instrument configurations were merged into a single dataset. The merged datasets were used for the data analysis. USANS measurement was conducted on the BL-1A USANS instrument at the Spallation Neutron Sourcecollectively using three wavelengths of 1.2, 1.8 and 3.6 A to cover the wavevector q range from 5 x I O3to 3 x | 03A ' . The samples were loaded into 2 -mm Hellma cells. The data were reduced with empty-cell background correction and presented in absolute intensity units.

[0133] Guinier-Porod model information and fitting approach. The Guinier-Porod fits follow the approach first described by Hammouda, 2010 J. Appl Crystallography 43, 716-719, doi: 10. 1107 / S0021889810015773. This method was selected because it can accommodate coexistence of poorly-defined and / or non-spherical structures, and because the fitting parameters have reasonably physical interpretations. The Guinier-Porod Model is entirely empirical. The details of the Guinier- Porod model information and fitting approach are further described in Vargo et al. 2023 Nature 623:724-731, https: / / doi.org / 10.1038 / s41586-023-06660-x, Supplementary Information Section 1.

[0134] Static solution USAXS. Absolutely calibrated USAXS and SAXS experiments were performed at beamline 9-ID at the Advanced Photon Source, Argonne National Laboratory. The combined q range is between 1 x 104A1and 1.3 A ': here q = 4ji / Xsin(0), in which X is the wavelength and 0 is half of the scattering angle. The X-ray energy was 21 keV (X = 0.5895 A). X-ray photon flux was approximately equal to 5 x 1012mm2s ' through a beam size of 0.5 x 0.5 mm. Data were reduced using USAXS instrument data reduction software and were desmeared from slit- smeared collimation of the Bonse-Hart USAXS system.

[0135] In situ SA-XPCS. In situ small-angle X-ray scattering and X-ray photon correlation spectroscopy (SA-XPCS) experiments were performed at beamline 8-ID-I at the Advanced Photon Source, Argonne National Laboratory. The X-ray energy is 10.9 keV; the horizontal beam size is 15 pm, as defined by the upstream guard slits, and the vertical beam size is 10 pm. To perform the drying experiments, 10-vol% Sl / NP solutions were loaded into quartz capillaries (2 mm outer diameter, Charles Supper). The capillaries were unsealed so that the solvent could freely evaporate. Owing to the small surface area of the capillary, the drying process took approximately 12 h. Scattering data were collected every 15 min. The diffusion of the liquid within 15 min was sufficient to avoid visible beam damage. Other than the known starting concentration, the local solution concentration could not be measured during the drying process. The 2D scattering intensity was collected using a Rigaku XSPA-500k detector. The fast dynamics (early stages of drying) were captured at a 50-kHz frame rate with a total acquisition time up to 2 s. The slow dynamics (later stages of drying) were captured at a 100-Hz frame rate with an adjustable total acquisition matching the timescales of the sample (50 s in this study). The SA-XPCS analysis was performed on high-performance Clusters using the APS Data Management System workflow. Both the SAXS and XPCS results were visualized, fitted and plotted using the graphic modules and the function libraries provided by pyXPCSviewer.

[0136] GTSAXS. GTSAXS measurements were performed at beamline 8-ID-E at the Advanced Photon Source, Argonne National Laboratory. The X-ray wavelength was 1.687 A and the scattering intensity distribution was captured by a Pilatus IM detector. A 2 x 2-cm silicon substrate was placed in a chamber designed for in situ measurements and aligned with the beam. A chloroform reservoir of a selected volume (here 350 or 500 pl) was injected into the chamber to slow the drying process andthen 100 j l of sample solution was drop-cast onto the substrate. GTSAXS measurements were taken at an incident angle of 0.8°.

[0137] TEM sample preparation and imaging. Bulk samples were embedded in resin (Araldite 502, Electron Microscopy Sciences) and cured at 60 °C overnight. Film samples were coated with resin and cured at 60 °C overnight. The silicon substrates were removed by submerging the resin- coated fdms in liquid nitrogen; owing to mismatched thermal expansivities, the nanocomposite fdm peeled away from the silicon and remained attached to the resin. Sections about 60 nm in thickness were microtomed using an RMC MT-X ultramicrotome (Boeckeler Instruments), floated on top of water and picked up on copper TEM grids. For samples without nanoparticles, iodine vapor was used to selectively stain the P4VP region. The thin sections were imaged using a FEI Tecnai 12 at an accelerating voltage of 120 kV. To produce high-resolution composite images (FIG. 6A), overlapping TEM images were collected and manually aligned in Photoshop using lower-magnification reference images.

[0138] Automatic nanosheet length and defect analysis. Image analysis code was performed in Python, using approaches translated from ADAblock, an Image J plugin developed by Murphy et al. In brief, greyscale TEM images were binarized using a local Otsu thresholding technique. The binarized images were used to draw 1 -pixel-thick skeletons that described the connectivity of the cross-section of each layer. The eight nearest neighbors of each skeleton pixel were used to label defects. A skeleton pixel with two nearest neighbors was considered defect-free, a skeleton pixel with only one nearest neighbor was labelled an end and a skeleton pixel with three or more nearest neighbors was labelled a junction. Connected junctions were combined to avoid double -counting. Because U-turn defects do not affect connectivity, they were not counted in this automated image -analysis routine. Each end defect was examined manually and U-turn defects were labelled as applicable.

[0139] To perform the sheet-length analysis, all junction pixels were deleted from the skeleton, leaving a set of isolated ID sheets. The length of each sheet was tallied in pixels and then converted to micrometers using the magnification of each image.

[0140] VOC removal efficiency tests. Films of S2 / NP, S2dls / NP, S2 and Sl / NP were prepared on circular 47-mm -diameter polytetrafluoroethylene air-sampling membranes (Pall, part number R2PJ047). In each test, the rim of the specimen was tightly held between the two flanges of a Teflon filter holder, which were fitted with 1 / 4" Teflon tubing. On one side, the filter holder was connected to a Teflon bag pre-filled with air that was enriched with a mixture of formaldehyde (70-230 ppb), acetaldehyde (10-90 ppb), acetone (1.9-4.3 ppm), 2-butanone (35-90 ppb) and hexaldehyde (40-95 ppb). Water vapor was added to the bag to achieve a relative humidity of 5-50%. Experiments were performed at room temperature (20-23 °C). Temperature and relative humidity were measured with an in-line digital T / RH sensor (HIH6100 series, Honeywell). On the other side of the filter holder, air was drawn from the bag through the specimen using a peristaltic pump that operated at a flow of 80- 90 ml min1. Once air flow through the specimen reached a steady-state regime, samples were collected simultaneously upstream and downstream of the specimen, by pulling air through 2,4-dinitrophenylhydrazine (DNPH)-impregnated silica gel cartridges (Waters Corp., part number WAT047205), over periods of 15-50 min. DNPH cartridges were subsequently extracted with 2 ml of carbonylfree acetonitrile (Honeywell) and the extracts were analyzed by high-performance liquid chromatography with UV detection (Agilent 1200), following the TO-11 method of the United States Environmental Protection Agency 53. The VOCs were identified on the basis of the retention times of authentic standards corresponding to their dinitrophenylhydrazine derivatives (Sigma- Aldrich). These standards were used to develop calibration curves for quantification. Reported values are the average of duplicate determinations obtained sequentially. The retention efficiency E of each compound i was determined asare the simultaneously measured upstream and downstream concentrations of compound z, respectively.

[0141] WVTR tests. The WVTR test set-up was informed by ASTM E96-00: ‘Standard Test Methods for Water Vapor Transmission of Materials’54. For each test, an aluminum jar (80 mm diameter, Joywee) was filled with 4 g of desiccant pellets (DampRid Moisture Absorber). A polyester sheet (127 pm thickness, McMaster-Carr) was heat-sealed around the mouth of the jar, forming a circular dish with a 5 -mm rim. Once cooled, the circular dish was removed from the jar and filled with 2.5 ml of 2.5-vol% sample solution. After the film dried, the polyester dish was turned upside down and glued with 5 Minute Epoxy (Devcon) to the desiccant-filled jar, creating a seal. Control samples were prepared following the same procedure, with 2.5 ml of pure chloroform substituted for the sample solution.

[0142] The initial weight of the sample was taken directly after the commercial epoxy bonded the sample to the dish cured. Samples were then placed on a perforated plastic platform above salt- saturated water, all within a sealed plastic container at ambient temperature and pressure to generate a 75% relative humidity environment. Weight measurements were taken once every 24-48 h to measure desiccant water mass gain through the test film, for three weeks after the initial weight was measured. The WVTR values were calculated by finding the least-squares fit of the sample mass versus collection time data. The slope of the fit was converted into a WVTR by dividing by the film area, A = 40TT mm2, for the jars used here. The standard deviation of the WVTR was calculated in the same way.

[0143] Calcium conductivity tests. Electrical calcium tests were used to compare the barrier properties of the nanocomposite with commercially available UV -curable epoxies. Each sample was prepared on a 125-pm polyethylene terephthalate (PET) substrate through a series of thermalevaporation steps. A pair of silver traces (100 nm thick, 2 x 15 mm2in size, 4 mm spacing) was thermally evaporated on the PET substrate. Calcium (100 nm thickness, 8 x 8 mm2in area) was thermally evaporated (pressure of 2-5 x 10 " Torr, deposition rate <0.8 A s ') on top of the silver,electrically connecting the two traces and resulting in an initial conductance of <0.1 S. Each sample was then prepared with the designated encapsulant and covered with a 125-pm PET cap. The decreasing conductance of the calcium sample is a result of oxidation in the presence of oxygen and moisture:

[0144] The commercial epoxies tested were DELO Katiobond LP655 and Ossila E132 epoxy. After application of the epoxy and PET cap, each sample was exposed to a UV lamp until fully cured before measurement. For nanocomposite samples, about 20 pl of S2 / NP solution was drop-casted, covered with the PET cap and left to assemble for about 1 h before measurement. Conductance of the encapsulated samples were measured over time (Keysight DAQ970A) in an enclosed environmental chamber (Associated Environmental Systems BHS-503, Acton) maintained at 20% relative humidity and 20 °C. The approximate barrier thickness for the commercial encapsulants were calculated on the basis of the repeated weight measurements of applied drops and the volumetric densities reported by the manufacturers.

[0145] Dielectric tests. Device fabrication. Indium tin oxide (ITO)-coated glass substrates (2-3 sq-i, Thin Film Devices, Inc.) were pre-cleaned using soapy water, deionized (DI) water, acetone and isopropanol, sequentially. The substrates were then heated at 100 °C for at least 4 h, followed by UV / Ch treatment for 20 min before use. Nanocomposite films were drop-cast on the ITO substrates as described above. After the films dried fully, they were placed in a vacuum chamber overnight to remove any residual solvent or moisture. The typical film thickness was about 2 pm.

[0146] Gold electrodes (1.13 num area with approximately 20 nm thickness) were deposited on the top surface of the film samples using athermal evaporator (MBRAUN). The ITO conductive coating was electrically connected to the ground using conductive silver paint (Ted Pella, Inc.). For comparison, benchmark BOPP (capacitor grade, about 3-4 pm) was obtained from PolyK Technologies, LLC. Gold electrodes (1.13 mrmarea with approximately 20 nm thickness) were deposited on both sides of the BOPP films using the same thermal evaporator (MBRAUN).

[0147] Device breakdown strength. Dielectric breakdown strengths were measured using a Trek 610D instrument amplifier as the voltage source based on an electrostatic pull-down method, in which a DC voltage ramp of 200 V s-1 was applied to the film samples until dielectric failure. The experimental dielectric breakdown measurements were analyzed with a two-parameter Weibull statistic, which can be described asP(£) = 1 - ex (-£ / « in which P(E) is the cumulative probability of dielectric failure, E is the measured dielectric breakdown field, the scale parameter a is the characteristic breakdown strength (that is, Weibull breakdown strength), which corresponds to a failure probability of 63.2% and the shape parameter ft isassociated with the distribution of data. A higher ft value refers to a narrower data spread. At least ten measurements were performed for each Weibull fitting.

[0148] Dielectric energy storage properties. Electric displacement-electric field (D-E) loops were collected under varied applied electric fields using a modified Sawyer-Tower circuit, which is integrated with a PK-CPE1801 high-voltage test system from PolyK Technologies, LLC. The voltages with a unipolar triangular waveform were applied to the film samples at a frequency of 100 Hz. Dielectric energy storage properties including discharged energy density and charge-discharge efficiency were derived from D-E loops.

[0149] Mechanical tests. Nanoindentation. Nanoindentation was performed to measure the reduced modulus and hardness of the nanocomposite coatings. We used a Hysitron TI-950 Triboindenter with a Berkovich tip (TI-0039-1, 50 nm tip radius). The coatings were attached to a silicon wafer using crystal bonds and placed at ambient conditions overnight for indentation. Twenty- five indentations were performed per sample with a maximum load of 1,000 pN and a loading rate of 20 pN s-i. The films were subjected to quasistatic indentation with a hold time of 30 s before unloading. The applied tip-area function was fitted using the reference material, polycarbonate, provided by Hysitron.

[0150] The Oliver and Pharr method was used to determine the reduced modulus and hardness56. The reduced modulus is defined asin which the modulus of elasticity, Eindenter, is 1,140 GPa, and the Poisson’s ratio of the indenter, vindenter is 0.07. The Poisson’s ratio of the sample was assumed as 0.34 to convert from the measured reduced modulus to the elastic modulus.

[0151] Cyclic buckling test. The cyclic buckling tests were performed on the nanocomposite coatings at room temperature using an MTS Tytron 250 testing machine (MTS Systems Corp.). The films were bent and stretched with a range of ±0.75 mm, at a frequency of 1 Hz, for a total of 600 cycles.

[0152] Recycling test. A bulk nanocomposite sample was prepared as described above. After drying, a portion of the sample was removed using a razor blade and prepared for TEM imaging. The remainder of the bulk sample was weighed and placed in a 20-ml glass vial. Chloroform was used to dissolve the dried sample; the volume of chloroform was selected to produce a 2.5-vol% solution. The bulk sample seemed to dissolve immediately and the solution was stirred overnight to ensure complete dissolution. The following day, another bulk sample was prepared as described above. TEM imaging confirmed that the recycled sample had the same lamellar structure as the original sample (FIGs. 8A-8D)

[0153] STEM tomography. Projection images for 3D electron tomography were collected using a FEI TitanX 60-300 microscope with a 10-mrad probe semi-convergence angle operated at 200 kV at the National Center for Electron Microscopy (NCEM) facility of the Molecular Foundry. Ahummingbird heavy tomography holder was used to acquire a series of TEM images at tilt angles in the range ±70° at an angular interval of 1°. The tilt series were aligned and reconstructed using the eTomo software of the IMOD tomography package. Reconstruction was done using the weighted- back-5 projection method. 3D visualization was performed using Tomviz 1.3.1.

[0154] Materials, methods, and results provided in this Example are further described in Vargo et al. 2023 Nature 623:724-731, https: / / doi.org / 10.1038 / s41586-023-06660-x, including extended data figures and tables and supplementary information. The entire contents of the foregoing materials are incorporated herein by reference.Example 2: Gradient structures in a self-assembling multilayer nanocomposite

[0155] The spontaneous formation of layer thickness gradients was explored in a self-assembling nanocomposite system. As provided in Example 1, the self-assembling nanocomposite system provided herein has produced a rich map of its self-assembly process, from dilute solution to dried composites. Among other unique behaviors, it is well-documented that the final ordered nanostructure is determined by the processing conditions — i.e., the drying rate — in addition to the system’s composition. This processing dependence is particularly striking at high molecular weights, likely due to the larger number of possible polymer configurations and the stabilizing effect of chain entanglements. Cross-sectional transmission electron microscopy (TEM) imaging has shown that, under varying drying conditions, one high-molecular-weight lamellar nanocomposite can form features anywhere from 72 nm to over 300 nm, compared to a “bulk” periodicity of 127 nm. Within a single nanocomposite film, the layer thicknesses can also vary spatially, smoothly increasing from the film-substrate interface to the upper film -air interface.

[0156] The nanocomposite blend consists of 6 nm ZrO? nanoparticles, 3 -pentadecylphenol (PDP) small molecules, and coil-comb supramolecules constructed from PDP and polystyrene -block- poly(vinyl pyridine) (PS-b-P4VP) block copolymers. The supramolecules’ comb blocks spontaneously form when PDP molecules hydrogen-bond to 4VP units in the BCP. Unbonded PDP and hydrogen-bonded PDP were distinguished because the two populations play distinct roles in the self-assembly process, and essentially act as two different components. Chloroform was selected as a solvent as it is a good solvent for the PS coil blocks, leading to a loose chain conformation at low concentrations. The small molecule PDP adds mobility to the system by diluting BCP entanglements, and increases the volume of the P4VP blocks. PDP has a solubility parameter between that of the BCP blocks and the NP ligands, so free PDP can relax the unfavorable interface between blocks or around NPs, and stabilize morphologies with large surface areas. Free PDP can also redistribute over relatively large distances to accommodate constraints. The intermediate strength of the hydrogen bonds gives the PDP some freedom to rearrange, and exchange between 4VP -bound states and free states is an open topic of research61. Much of the self-regulating behavior of this complex system can be attributed to the small molecule.

[0157] Within a drying drop-cast film, the solute concentration is a function of both time and depth (FIG. 9A). Thus, at every time point until the film is fully dry, the solute and solvent fractions form a smooth gradient through the thickness of the film. Using a high-molecular-weight supramolecular nanocomposite blend, the characteristic layer width, f is varied by varying the film’s drying rate and duration. Nanocomposite films that were dried quickly have relatively small domain thicknesses, while slowly-dried films exhibit significantly larger f values (FIGs. 9B-9E). In addition to substantial differences between samples, we also observe pronounced f gradients within individual samples. The system can be kinetically-trapped in lower-f states via microdomain collapse upon rapid solvent removal. However, the presence of higher-f states cannot be explained by the same mechanism. Every sample shown in FIGs. 9B-9E has the same composition, film thickness, and initial concentration. The underlying mechanism involves a combination of entropic, enthalpic, and kinetic factors.Structural characterization with X-Ray scattering

[0158] The gradient structures’ strong dependence on processing history implies that they are kinetically-trapped states rather than thermodynamic equilibria. However, in-situ small-angle x-ray scattering (SAXS) suggests additional factors to the mechanism. The nanocomposite’s assembly process was observed from a starting concentration of 10 vol%, mapping the full structural evolution (FIG. 10A). If the solution is given time to slowly dry after the appearance of sharp lamellar structure factor peaks, the peaks will eventually broaden and shift toward lower q values. The q shift is easily interpreted: the volume-averaged feature size is growing larger. The structure peak broadening is more unusual. It often corresponds to the formation of small grains, as described by the Scherrer equation. Technically, however, it means only that the structure of the nanocomposite is deviating from perfectly periodic lamellae. Cross-sectional imaging of dried samples confirm that they maintain the nearly-perfect domain orientation (i.e., grain sizes larger than the x-ray probe) that emerges around a solute concentration of -30%. Thus, the structure factor peak broadening was used to identify the emergence of the gradient structure. Notably, gradients only emerge after the formation of highly-ordered, large grains of oriented lamellae with a uniform microdomain periodicity. This implies that either the gradient structure is energetically preferable to the periodic lamellar structure, or that the system's energetics change after the formation of the periodic lamellae.

[0159] In addition to the in-situ study, static USAXS, SAXS, and WAXS measurements of fully- dried films — with gradient structures and without — were collected to probe features with length scales from Angstrom to microns (FIGs. 10B-10D) The USAXS-SAXS scattering profiles, while simple, offered satisfactory answers to a few outlying questions. First, they confirm that we are indeed seeing a net increase in the lamellar thickness; the increase at the top of the film is not compensated by a decrease elsewhere. They also confirmed that the varying periodicities observed in the cross-sectional TEM images are representative, because USAXS probes a much larger sample volume. The scattering results verify that the gradients are not an optical illusion produced by tilted lamellae.

[0160] The WAXS peaks describe the Angstrom -level small molecule behavior, corresponding to PDP and NP ligand organization. In addition to the static WAXS performed on dry samples, solution WAXS data were collected using a solution-fdled capillary (FIG. 10C). Due to its long aspect ratio, the capillary included a range of solvent concentrations, clearly distinguishable by their structural color. The static sample could therefore be used to approximate an in-situ study of the small molecule behavior throughout the drying process. Peak Hi in FIGs. 10C & 10D is consistent with the WAXS signature of crystallized PDP at 4.17 A (M. C. Luyten et al. 1999 Macromolecules 32, 13, 4404- 4410). Peaks iv and v were matched to the NP ligands using an NP-only control sample. The volumetric NP concentration is expected to be proportional to the solute concentration, because the NPs do not aggregate in slowly-dried samples. Therefore, the relative height of peak Hi compared to peaks iv and v describe the amount of PDP crystallization relative to a fixed amount of solute.

[0161] As the solution dries, the crystallized PDP peak intensity overtakes the NP peak intensities in the WAXS data, suggesting that increasing lengths of the P4VP backbone become fully saturated with hydrogen-bonded small molecules. The relative amount of PDP is fairly consistent between the driest solution sample and three of the four fully-dried samples. Based on their structural color, and cross-sectional TEM imaging, these three samples have average domain spacings less than or equal to the previously-reported “bulk” periodicity. However, the fourth dried sample, whose red color suggests much a larger f at the top surface of the film, has substantially less crystallized PDP. The WAXS results suggest that the gradient formation is linked to a net decrease in the amount of crystallized PDP.Structural characterization with image analysis

[0162] The direction of the PDP redistribution could be identified by simply reexamining the existing library of cross-sectional TEM images. Assuming the lamellar cross-sections are representative samples, the 2D slices can be expanded into a 3D structure. From the 3D structures, the distribution of every component can be calculated by making three assumptions: that each component is incompressible and its density remains constant, that PS and P4VP are fully separated across the microdomain boundaries, and that there is no long-range (multi-domain) PDP redistribution. In crosssections with no gradients, given the near-equal domain widths of ~64 nm, nearly all of the unbonded PDP was found to be inside of the PS domains, not co-crystallized within the combs. This is consistent with the conclusion that the high-molecular-weight self-assembly is entropy-driven. As discussed in Example 1, the small molecules lower the enthalpic driving force, because they are miscible in both blocks, and increase the system’s potential mixing entropy. As the solvent evaporates, enthalpy becomes more important: the small molecules prefer to be in the comb domains, where the alkyl molecules can stack via favorable van der Waals interactions. The supramolecular nanocomposite explored here and previously, 330-6-125 kDa with a 1.6 molar ratio of PDP small molecules, is expected to form PS cylinders if all of the small molecules are sequestered in the combdomains. The lamellae themselves, not just their excellent order, are the result of entropy-driven selfassembly.

[0163] When the same analysis is performed on a sample with a distinct I gradient, increasing fractions of the unbonded PDP were found to be self-segregating to the comb domains (FIGs. 11A- 11C). The microdomains were both larger and increasingly asymmetric: 108 nm coil domains were paired with 225 nm comb domains, for example. At the largest 1 values, all PDP was estimated to be within the comb domains. This behavior can be qualitatively understood as a variation on the Dilution Approximation used for BCP solutions. To calculate the effective / of a BCP partially mediated by nonselective solvent molecules, one can simply multiply the of the BCP melt by the solute fraction. As the solvent fraction approaches 100%, the effective approaches 0- unfavorable interactions are entirely shielded by solvent molecules. In the nanocomposite system, PDP also acts like a solvent, albeit a more selective one. Based on this understanding of enthalpy in a BCP solution, we expect the PDP redistribution experiences a “positive feedback loop”. Decreasing solvent fraction creates an increasing enthalpic preference for small molecules to distribute within the comb domains only. As the small molecules begin to segregate to the comb domains, the supramolecules shift position on the BCP phase diagram along both axes. The N increases, because the PDP molecules no longer act like solvent. The f also changes, because one block is losing volume (small molecules) while the other is gaining volume (FIG. 11C). Because the solvent concentration within the drying film varies spatially — lower on top, higher on the bottom — the extent of PDP redistribution follows a corresponding gradient through the thickness of the film.

[0164] Importantly, this explanation of the PDP behavior does not directly point to the formation of I gradients: it instead implies that the system will undergo a morphological transition from lamellae to cylinders. Here, finally, we hypothesize that we are seeing the kinetic effects of the supramolecules’ high molecular weight. A lamellae-to-cylinders morphological transformation requires large-scale rearrangement of the BCPs themselves. At almost 500 kDa, the high molecular weight BCPs are effectively pinned along the domain boundaries by coil-coil entanglements. In response to the increasing cross-sectional mismatch between the smaller coil and larger comb domains, the supramolecules are not able to form curved interfaces. Instead, we predict, the comb domains extend away from the coil-comb interfaces. The high small molecule content within the domain means that this rearrangement can be performed without too much unfavorable chain stretching; the small molecules can fill in volume as needed.

[0165] This mechanism, explains all of the scattering data, and the asymmetry of the large- ( microdomains. It also explains a seemingly-unrelated observation: drop-cast films with pronounced gradient structures have rough, scaly surface textures (FIGs. 11D-11E). Cross-sectional TEM images show an unusually high number of isolated end defects toward the top surface of the gradient films (FIGs. 11F-11G) The paired end defects that dominate in non-gradient structures could act like “sliding doors” to relieve the stress of the top layers’ shape change. As many individual defects pull away from each other, the smooth film surface is broken into irregular terraces.Control studies with related systems

[0166] The presence of surface texture is a convenient proxy for the presence of gradient structure along a film’s cross-section. We performed a series of control experiments to test the proposed mechanism of PDP redistribution. Six control samples were studied to determine whether excess PDP and / or NPs were essential for the formation of gradient structures (FIGs. 11A-11F). As expected, the samples without excess PDP exhibited significantly less surface roughness; the NPs did not have a significant effect on the formation of gradient structures. Cross-sectional TEM of the low-PDP samples showed ordered, uniform lamellae (FIG. 11G). The system without excess PDP, as defined by the stoichiometric 1: 1 4VP:PDP ratio, likely still had unbonded PDP to aid its assembly. As discussed above, longer polymers are not able to accommodate as many small molecules as short polymers with the same monomer chemistry, due to their reduced free volume. The amount of unbonded PDP, however, was too small to cause a sizable morphological transition.

[0167] Next, analogous systems were used at lower molecular weights to probe the role of kinetics. For simplicity, no NPs were used, because the previous control studies suggested they did not play a large role in gradient formation. Supramolecules constructed with 104-6-30 and 50-6-17 kDa BCPs had similar coil-comb ratios, as summarized in Table 3. S2 and S3 were self-assembled under the slow-drying conditions. The cross-sectional structures showed evidence of the same PDP redistribution process observed in SI (FIGs. 12H-12I). The S2 blend formed layers with pronounced ( gradient, with f values ranging from 48 nm at the bottom of the film to 102 at the top — a 113% increase. The S3 blend, on the other hand, had large grains of cylindrical microdomains. At this lower molecular weight, the system is partially able to achieve its thermodynamically-determined structure, and does not need to form an f gradient.Table 3. Compositions of the blends studiedThe supramolecule notation includes the molecular weight of the PS and P4VP blocks. PDP molecules are expected to hydrogen-bond to 4VP monomers at a 1-to-l ratio, denoted P4VP(1).

[0168] Finally, the effect of slow, multiple-day drying processes was studied. Drop-cast films dried over a span of 3 days exhibited constant and high f values of 251-311 nm through their entire thickness (FIGs. 12J-12K). There was no significant surface texture at the film-air interface. In the cross-sections, regions of pinched-off lamellae suggest that the system had nearly enough mobility to undergo a full morphological transition to cylindrical domains. As a comparison, the films shown in FIGs. 9C-9E were slowly dried for one day in a solvent-rich environment, then quickly transferred to solvent-free conditions. Though the top of the samples appeared to be dry after one day, the differentstructure of the three-day film confirms that there was still solvent left in the lower layers of the film. Based on simultaneous structural color and film thickness measurements, gradient formation is estimated to begin when the film has, on average, 20-30% solvent by volume (FIG. 13). However, as discussed, the film’s concentration varies spatially throughout the entire drying process, so the precise transition point is difficult to pinpoint.Gradient films as photonic crystals

[0169] The films’ layer thicknesses are comparable to wavelengths of visible light, and their vibrant structural color confirms that they cause constructive and destructive interference of specific wavelengths. A periodic lamellar nanocomposite, with a single consistent f, is an example of a ID photonic crystal. Slightly aperiodic structures, like the f gradient films, are optically more complicated. Given a nearly-continuous transition between layer thicknesses, they can exhibit interference across a range of wavelengths rather than a single wavelength. In the optics community, this geometry is referred to as a chirped photonic crystal, and their optical properties are not completely understood. However, they appear to be useful as broadband filters, because they can interact with a range of wavelengths at once.

[0170] Reflectance measurements were performed on nanocomposite films with periodicity gradients (FIG. 14A-14B). To prevent thin-film interference peaks in the reflectance spectra, the films were thicker than usual: ~30 pm. Due to the increased thickness, the drying rate was not easily controlled, so the dried films exhibited f gradients in the plane of the substrate in addition to the usual f gradients perpendicular to the substrate (FIG. 14A, inset). Most regions of the gradient films could filter bands of wavelengths around 50-100 nm wide. Notably, the regions with the most significant gradients, identified by their red structural color, had nearly-uniform reflectance in the visible range. It is possible that they deviate too far from a periodic structure to fulfill Bragg conditions, and no longer act as photonic crystals. Or, their rough surfaces cause light to scatter, reducing the reflection intensity. In addition to serving as light filters, f gradient films may have other useful optical properties. For example, flat lenses and zone plates focus light using concentric rings with gradient widths.Summary

[0171] The relative free energies of the nanocomposite’s various morphologies can be estimated. The relative free energies are a function of the solute concentration, because of the changing PDP distribution. Due to the supramolecules’ high molecular weights, the polymers begin to interact at solute concentrations below 10 vol%. At such high solvent concentrations, the PDP has no enthalpic preference between blocks, and is distributed almost uniformly across the domains. The nanocomposite’s effective block ratio, fcon, is around 0.48, so lamellae are the preferred morphology. The lamellae are stabilized by chain entanglements, and order rapidly. If the sample undergoes rapid drying in this regime, the result is macroscopically -oriented, uniform lamellae. Despite being highly- ordered and uniform, uniform lamellae are energetically-unfavorable once the solvent has evaporated.As the solvent continues to evaporate, the effective between the coil and comb domains increases, and the PDP molecules begin to segregate to the comb domains. Their redistribution further increases the x value and shifts the effective block ratio to fCOii= 0.29. Cylinders are the lowest-energy structure, but require global rearrangement across microdomain boundaries. Asymmetric, stretched lamellae are a compromise: less favorable than cylinders, but possible via short-range rearrangement.

[0172] Layered nanocomposites with gradient periodicity can be fabricated by modulating processing conditions and compositions, such as small molecule (e.g., PDP) concentration, unbonded and hydrogen-bonded small molecule ratios, BCP (e.g., PS-A-P4VP) molecular weight, and drying rate and conditions. Generally, slower drying rate and / or higher solute ratio in the solute / solvent mixture provides nanosheets that are thicker and redder (less blue) in color. Further, small molecule mobility (chemical or cross-linking) can be modulated to obtain nanocomposite materials of morphology of interest. The nanocomposite materials provided herein, particularly nanocomposite materials with gradient layer thickness and property, have unique optical properties and can be used as optical materials such as light filters, flat lenses, and zone plates.

[0173] In the foregoing specification, the invention has been described with reference to specific embodiments. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of invention.

Claims

CLAIMSWhat is claimed is:

1. A nanocomposite material comprising nanoparticles, small molecules, and block copolymer (BCP)-based supramolecules, the BCP-based supramolecules comprising BCPs and small molecules, and the nanoparticles, the small molecules, and the BCP-based supramolecules self-assembled into a plurality of nanosheets that form the nanocomposite material.

2. The nanocomposite material of claim 1, wherein each of the BCP-based supramolecules comprises a BCP and small molecules bound to the BCP via non-covalent bonds; or wherein the BCP comprises a molecular weight of about 130 kDa to about 600 kDa.

3. The nanocomposite material of claim 1, wherein the small molecules are organic molecules comprising a molar mass of about 50 g / mol to about 1500 g / mol.

4. The nanocomposite material of claim 1, wherein the nanoparticles are inorganic molecules comprising about 3 nm to about 50 nm in size, about 3 nm to about 9 nm in size, or about 6 nm in size; or wherein the nanoparticles comprise nanoparticles of metal oxide, zirconium oxide (ZrO?). noble metal, gold, or silica.

5. The nanocomposite material of claim 1, wherein the nanoparticles comprise ZrCT: wherein the small molecules comprise 3 -pentadecylphenol (PDP); wherein the BCP comprises polystyrene-Woc -poly(4-vinyl pyridine) (PS-6-P4VP); and wherein the BCP-based supramolecules comprise PS-6-P4VP(PDP)i, comprising PDP bound to pyridine side chains of the PS-A-P4VP via hydrogen bonding.

6. The nanocomposite material of claim 1, wherein the nanoparticles comprise about 3-20% volume, the small molecules comprise about 10-25% volume, and BCP-based supramolecules comprise about 65-75% volume of the nanocomposite material.

7. The nanocomposite material of claim 1, wherein each nanosheet is about 50 nm to about 410 nm thick; wherein the nanocomposite material comprises about 200 or greater number of nanosheets;and wherein the nanocomposite material comprises about 0.06 pm-2or less defect density.

8. The nanocomposite material of claim 1, comprising an improved barrier function against a volatile organic compound (VOC), water, oxygen, or electron relative to a control material.

9. The nanocomposite material of claim 8, comprising VOC removal efficiency of 40% or more, water vapor transmission rate (WVTR) of 8 g nr2day' 'or less, dielectric breakdown strength of 500 MV / nr1or more, maximum discharged energy density of 3 J cm'3or more, or encapsulant lifetime of 3 min pm1or more.

10. The nanocomposite material of claim 1, comprising the plurality of nanosheet with a gradient layer thickness.

11. The nanocomposite material of claim 10, wherein the thickness of nanosheets in the nanocomposite material ranges from about 65 nm to about 135 nm, from about 120 nm to about 280 nm, from about 120 nm to about 250 nm, or from about 120 nm to about 410 nm.

12. The nanocomposite material of claim 1, comprising alternating layers of a nanoparticle -rich nanosheet and a nanoparticle-poor nanosheet.

13. A method of producing a nanocomposite material, the method comprising: contacting an initial blend of nanoparticles, small molecules, and block copolymer (BCP)- based supramolecules with a solvent to form a mixture, the BCP -based supramolecules comprising BCPs and small molecules; and drying the mixture to remove the solvent, forming via a self-assembly process the nanocomposite material comprising a plurality of nanosheets comprising the nanoparticles, the small molecules, and the BCP-based supramolecules.

14. The method of claim 13, wherein the solvent is chloroform or benzene.

15. The method of claim 13, wherein contacting comprises contacting the initial blend with the solvent that is about 95% to about 100% volume, or about 97.5% volume of the mixture.

16. The method of claim 13, wherein drying comprises removing the solvent to initiate the self-assembly process at a volume percent of solvent in the mixture of about 70% to about 80% or lower; andwherein drying comprises from about 20 minutes to about 3 days.

17. The method of claim 13, wherein the method further comprises adjusting the drying rate or solute / solvent ratio in the mixture to adjust thickness or color of the plurality of nanosheets, wherein a slower drying rate or a higher solute ratio in the mixture generates a thicker or redder colored nanosheet.

18. The method of claim 13, wherein the mixture is drop-cast onto a substrate before drying the mixture.

19. The method of claim 18, wherein the substrate is a solid, a lens, a membrane, a fdm, or a wafer made of Teflon, polyester, silicon, or glass.

20. The method of claim 13, wherein the BCP-based supramolecules each comprise a BCP and small molecules bound to the BCP via non-covalent bonds; wherein the BCP comprises a molecular weight of about 130 kDa to about 600 kDa; or wherein the small molecules are organic molecules comprising a molar mass of about 50 g / mol to about 1500 g / mol.

21. The method of claim 13, wherein the nanoparticles are inorganic molecules comprising about 3 nm to about 50 nm in size, about 3 nm to about 9 nm in size, or about 6 nm in size; or wherein the nanoparticles comprise nanoparticles of metal oxide, zirconium oxide (Zr(T). noble metal, gold, or silica.

22. The method of claim 13, wherein the nanoparticles comprise ZrCT: wherein the small molecules comprise 3 -pentadecylphenol (PDP); wherein the BCP comprises polystyrene-Woc -poly(4-vinyl pyridine) (PS-6-P4VP); and wherein the BCP-based supramolecules comprise PS-6-P4VP(PDP)i, comprising PDP bound to pyridine side chains of the PS-A-P4VP via hydrogen bonding.

23. The method of claim 13, wherein each nanosheet is about 50 nm to about 410 nm thick; wherein the nanocomposite material comprises about 200 or greater number of nanosheets; andwherein the nanocomposite material comprises about 0.06 pm-2or less defect density.

24. The method of claim 13, wherein the nanoparticles comprise about 3-20% volume, the small molecules comprise about 10-25% volume, and BCP-based supramolecules comprise about 65-75% volume of the initial blend.

25. The method of claim 13, wherein forming comprises forming alternating layers of a nanoparticle -rich nanosheet and a nanoparticle -poor nanosheet.

26. A nanocomposite material produced by the method of 13.

27. A product comprising the nanocomposite material of 1, wherein the product is a barrier product or an optical product.

28. The product of claim 27, comprising a volatile organic compound barrier, a water barrier, an oxygen barrier, an electron barrier, a dielectric capacitator, a lens coating, a packaging, a light filter, a flat lens, and a zone plate.

29. A product comprising the nanocomposite material of 26, wherein the product is a barrier product or an optical product.

30. The product of claim 29, comprising a volatile organic compound barrier, a water barrier, an oxygen barrier, an electron barrier, a dielectric capacitator, a lens coating, a packaging, a light filter, a flat lens, and a zone plate.

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