Temperature-sensitive nano-carrier based on biomass core and preparation method and application thereof

Abstract

This invention relates to a thermo-responsive nanocarrier based on a biomass core, its preparation method, and its applications. First, using hydroxyl-containing biomass materials such as cyclodextrin and cellulose nanocrystals as a core, a macromolecular initiator with ATRP initiating groups modified on its surface is prepared through an acylation reaction. Then, the macromolecular initiator is mixed with thermosensitive monomers such as N-isopropylacrylamide for ATRP polymerization to obtain a thermo-responsive nanocarrier. Next, the thermo-responsive nanocarrier is blended with functional reagents such as antibacterial agents to obtain a supported thermo-responsive nanocarrier. Finally, the supported thermo-responsive nanocarrier is mixed with a matrix material such as textile fibers to obtain a supported thermo-sensitive functional material. The preparation method of this invention has the advantages of simple process, green and controllable characteristics, and the obtained thermo-responsive nanocarrier can be widely used in the field of functional materials in light industries such as textiles, leather, and footwear, endowing related products with various intelligent properties.

Description

Technical Field

[0001] This invention relates to the fields of functional materials and biomass composite materials, specifically to a temperature-sensitive responsive nanocarrier based on a biomass core, its preparation method, and its application. Background Technology

[0002] The upgrading of consumption and the high-quality development of the light industry have placed higher demands on the functionality, comfort, and intelligence of end products such as textiles, leather products, and footwear materials. How to endow such flexible substrates with intelligent functions such as dynamic response, long-lasting antibacterial effect, and slow-release fragrance has become an important research direction in the fields of textiles, leather, and footwear.

[0003] Currently, in typical light industrial material processing systems such as leather finishing, antibacterial and aromatic functional additives are often directly physical blended with conventional coating matrix materials such as acrylic resin and polyurethane resin and then applied to the leather surface. This method easily leads to a series of problems such as uneven distribution of functional components, poor functional durability of products during use and storage, and uncontrolled volatilization of functional additives in non-working states. This not only significantly reduces the effective utilization rate of functional additives, but also easily causes premature decay of related functions, making it difficult to achieve stable and long-lasting intelligent functional expression, thus restricting the performance improvement and application expansion of high-end functional light industrial products.

[0004] Nanoparticle-based loading technology provides an effective solution for the efficient encapsulation, stable loading, and controlled release of functional reagents. However, traditional nanoparticles such as liposomes and polymer micelles generally suffer from drawbacks such as poor biocompatibility, insufficient environmental friendliness, complex preparation processes, limited environmental response mechanisms, and uncontrollable release behavior, making them unsuitable for the green and practical application requirements of light industrial materials. Furthermore, temperature, as the most direct physical signal of interaction between the human body and the external environment, is an ideal triggering factor for constructing smart responsive materials due to its sensitive response and ease of control. Although thermosensitive nanoparticles have been widely researched and applied in fields such as biomedicine, their large-scale application in light industrial sectors such as textiles and leather still faces significant bottlenecks due to complex synthesis processes, high raw material costs, and insufficient compatibility with light industrial substrates.

[0005] The light industry is currently accelerating its transformation towards green, low-carbon, and sustainable manufacturing. Various natural biomass materials (such as cyclodextrin, cellulose, and chitosan), with their advantages of wide availability, renewability, excellent biocompatibility, molecular structure rich in active sites like hydroxyl groups, and ease of chemical modification, are showing great application potential in the field of functional materials for the light industry. How to fully leverage the structural and environmentally friendly characteristics of green biomass materials, combined with the intelligent response behavior of temperature-sensitive polymers, to construct novel intelligent nanocarrier systems that are simple to prepare, cost-effective, have adjustable release behavior, and are adaptable to light industry application scenarios, achieving stable loading and on-demand controllable release of functional components, and solving common industry technical problems such as low utilization rate and poor functional durability of existing functional additives, has become a key issue urgently needing breakthroughs in the field of functional materials for the light industry. Summary of the Invention

[0006] The main objective of this invention is to overcome the aforementioned shortcomings of the existing technology and provide a nanocarrier with excellent temperature-sensitive responsiveness, its preparation method, and its applications. This nanocarrier uses natural biomass materials as its core, and forms a "core-shell" or "star-shaped" nanostructure through controlled polymerization grafting of temperature-sensitive polymer chains, enabling it to efficiently load and intelligently release functional reagents.

[0007] The preparation method of the thermo-responsive nanocarrier based on biomass core described in this invention mainly includes: mixing biomass material with an acylation reagent to carry out an acylation reaction to obtain a macromolecular initiator; mixing the macromolecular initiator with a thermo-sensitive vinyl monomer to carry out an atom transfer radical polymerization (ATRP) reaction to obtain the thermo-responsive nanocarrier.

[0008] In the above scheme, the biomass material is selected from biomass materials containing at least one hydroxyl group, including but not limited to α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, pentaerythritol, trimethylolpropane, xylitol, sorbitol, cellulose nanocrystals, partially deacetylated chitosan, etc.

[0009] In the above scheme, the biomass material needs to be pretreated before the reaction, and the pretreatment includes drying and dehydration.

[0010] In the above scheme, the acyl bromide reagent is specifically a bromine-substituted organic compound, including but not limited to 2-bromoisobutyryl bromide, 2-bromopropionyl bromide, α-bromophenylacetyl bromide, 2-bromoisobutyric anhydride, 2-bromopropionic anhydride, etc.

[0011] In the above scheme, the specific process of the acylation reaction is as follows: Under an inert atmosphere, biomass materials, solvent A, and acid-binding agent are mixed evenly. The resulting mixture is placed in an ice-water bath, and the acylation reagent is added dropwise. After the addition is complete, the mixture is stirred in the ice-water bath for 0.5-3 hours. Then, the temperature is increased to carry out the acylation reaction. After the reaction is complete, the product is separated and purified by extraction, rotary evaporation, or recrystallization to obtain a macromolecular initiator (B-Br). The surface of this macromolecular initiator is modified with an atom transfer radical polymerization (ATRP) initiating group, which can initiate the ATRP polymerization reaction of thermosensitive vinyl monomers.

[0012] In the above scheme, the molar ratio of biomass material, acylation reagent, and acid-binding agent required for the acylation reaction is 1:10-15:10-15.

[0013] In the above scheme, the inert atmosphere is specifically a nitrogen or argon atmosphere.

[0014] In the above scheme, solvent A is selected from at least one of N,N-dimethylformamide (DMF), dimethyl sulfoxide (DMSO), and tetrahydrofuran (THF).

[0015] In the above scheme, the acid-binding agent is selected from at least one of triethylamine, pyridine, and potassium carbonate.

[0016] In the above scheme, the acylation reaction temperature is 15-25℃ and the reaction time is more than 24 hours.

[0017] In the above scheme, the specific process of the ATRP reaction is as follows: a macromolecular initiator and a thermosensitive vinyl monomer are added to solvent B. The resulting mixture is first subjected to freeze-thaw cycle deoxygenation treatment, then a catalyst and ligand are added and mixed evenly. The mixture is then heated in an inert atmosphere to carry out the ATRP reaction, and the reaction is terminated by liquid nitrogen freezing. The product is purified by dialysis and freeze-dried to obtain a thermosensitive responsive nanocarrier. Throughout the reaction process, the length of the grafted polymer chain can be precisely controlled by adjusting factors such as the ratio of monomer to initiation sites and the reaction time.

[0018] In the above scheme, the thermosensitive vinyl monomer is selected from at least one of N-isopropylacrylamide (NIPAM), N-ethylacrylamide (NEAM), N,N-diethylacrylamide (DEAA), N-vinylcaprolactam (NVCL), and 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA).

[0019] In the above scheme, solvent B is selected from at least one of tetrahydrofuran (THF), dimethyl sulfoxide (DMSO), N-methylpyrrolidone (NMP), and toluene (TOL).

[0020] In the above scheme, the catalyst is selected from at least one of cuprous bromide, cuprous chloride, and triphenylphosphine.

[0021] In the above scheme, the ligand is selected from at least one of N,N,N,N,N-pentamethyldiethylenetriamine (PMDETA), tris(2-pyridylmethyl)amine (TPMA), tris(2-aminoethyl)amine (TREN), and diethylenetriamine (DETA).

[0022] In the above scheme, the specific process of the freeze-thaw cycle deoxygenation treatment includes: freezing the mixture at a low temperature of -50℃ to -80℃ for about 5-20 minutes, then thawing it by introducing nitrogen gas, and repeating the freeze-thaw cycle multiple times (e.g., 2-5 times).

[0023] In the above scheme, the molar ratio of the macromolecular initiator to the temperature-sensitive vinyl monomer required for the ATRP reaction is 1:10-40. The ATRP reaction temperature is 60-80℃, and the reaction time is 4-8 hours.

[0024] The above scheme further includes: mixing the prepared thermo-responsive nanocarrier with a functional reagent to obtain a supported thermo-responsive nanocarrier; and mixing the supported thermo-responsive nanocarrier with a matrix material to obtain a thermo-responsive composite functional material.

[0025] The specific process for preparing the supported thermo-responsive nanocarrier in the above scheme includes: adding the thermo-responsive nanocarrier to deionized water at 0-20℃ (below the low critical dissolution temperature LCST of the thermo-responsive nanocarrier), stirring to fully dissolve it, and obtaining a carrier solution with a mass fraction of 10%-20%; adding the functional reagent to the carrier solution and stirring for 6-12 hours, followed by dialysis separation and freeze drying to obtain the supported thermo-responsive nanocarrier.

[0026] In the above scheme, the mass ratio of the thermo-responsive nanocarrier to the functional reagent is 1:0.2-2.

[0027] In the above scheme, the functional reagent is selected from at least one of antibacterial agents (such as silver nanoparticles, benzalkonium chloride, polyhexamethylene biguanide), fragrances (such as tea tree oil, cinnamaldehyde, menthol, santalol, etc.), phase change materials, dyes, or waterproofing agents.

[0028] The specific process for preparing thermo-responsive composite functional materials in the above scheme includes: introducing and uniformly dispersing a supported thermo-responsive nanocarrier into a matrix material using methods such as liquid-liquid mixing (e.g., liquid-liquid blending), liquid-solid mixing (e.g., impregnation, coating), and solid-solid mixing (e.g., solid-solid blending), to obtain the thermo-responsive composite functional material. This process mainly relies on hydrophobic interactions, host-guest inclusion (targeting the cyclodextrin core), or physical adsorption to achieve the loading of functional reagents.

[0029] In the above scheme, the mass ratio of the loaded temperature-sensitive nanocarrier to the matrix material is 1:1-20.

[0030] In the above scheme, the matrix material is selected from at least one of light industrial materials such as textile fibers, leather, and shoe polymer materials.

[0031] A second objective of this invention is to provide a thermo-responsive nanocarrier, a supported thermo-responsive nanocarrier, or a thermo-responsive composite functional material. The thermo-responsive nanocarrier or supported thermo-responsive nanocarrier has a core-shell structure, wherein the core is a modified biomass material, and the shell is a thermo-sensitive polymer obtained through ATRP polymerization or a thermo-sensitive polymer loaded with a functional reagent. The thermo-responsive composite functional material includes a supported thermo-responsive nanocarrier and a matrix material, wherein the supported thermo-responsive nanocarrier is uniformly dispersed in the matrix material.

[0032] The third objective of this invention is to provide applications of the above-mentioned thermo-responsive nanocarriers or loaded thermo-responsive nanocarriers or thermo-responsive composite functional materials in the preparation of smart textiles, smart leather products, smart footwear materials, etc.

[0033] This invention utilizes the acylation reaction between biomass materials and an acylation reagent to obtain a macromolecular initiator with ATRP initiating groups modified on its surface. This initiator then undergoes ATRP polymerization with thermosensitive monomers such as N-isopropylacrylamide, thereby producing a thermosensitive responsive nanocarrier and a final thermosensitive responsive composite functional material. The acylation reaction involves a nucleophilic addition-elimination reaction between a hydroxyl group and an acylation bromide, generating an ester and simultaneously releasing hydrogen bromide. The ATRP reaction is a controlled / living radical polymerization reaction, achieving polymer synthesis with controllable molecular weight and low dispersity through a reversible redox reaction that dynamically balances dormant species and active radicals. The principles of the two reactions are as follows:

[0034]

[0035] Compared with existing similar products or technologies, the innovations and beneficial effects of this invention are mainly reflected in the following aspects: (1) Green core design: Biomass materials containing multiple hydroxyl groups are selected as the core framework of the nanosystem, which not only improves the biodegradability and environmental compatibility of the carrier, but also provides a platform for subsequent initiator fixation and high-density polymer grafting, avoiding the defects of traditional petroleum-based core materials.

[0036] (2) Controllable synthesis strategy: Through precise acylation reaction, the hydroxyl groups of the biomass core are converted into ATRP initiation sites. Utilizing the high efficiency and controllability of ATRP technology, temperature-sensitive polymer chains are grown in situ on the surface of the biomass core, thereby precisely controlling the polymer chain length, density and nanoparticle size.

[0037] (3) Multifunctional integration: The prepared temperature-sensitive nanocarrier has a clear "hydrophilic-hydrophobic" transition characteristic. At low temperatures (such as below LCST temperature), the polymer chains extend hydrophilically, the carrier is well dispersed, and it is easy to load functional reagents. When the temperature rises (such as above LCST temperature), the polymer chains dehydrate and shrink, driving the carrier structure to change, thereby realizing the rapid and intelligent release of functional reagents such as antibacterial agents, fragrances, and phase change materials.

[0038] (4) Wide range of light industry applications: This nanocarrier system can be widely used in the finishing of fiber textiles, modification of leather top coating agents and preparation of shoe composite materials (such as insoles and linings) through conventional processes such as impregnation, coating and blending, providing core material support for the development of next-generation light industrial products with intelligent temperature regulation, long-lasting freshness and odor management. Attached Figure Description

[0039] Figure 1 The image shows the dynamic mechanical light scattering analysis results of the pentaerythritol-based thermosensitive nanocarrier prepared in Example 2.

[0040] Figure 2 This is a TEM image of the pentaerythritol-based thermosensitive nanocarrier prepared in Example 2.

[0041] Figure 3 The image shows the dynamic mechanical light scattering analysis results of the menthol-loaded thermosensitive nanocarrier prepared in Example 2.

[0042] Figure 4 This is a TEM image of the menthol-loaded thermosensitive nanocarrier prepared in Example 2.

[0043] Figure 5 This is the control group leather coating prepared in Example 2.

[0044] Figure 6 The leather coating with temperature-sensitive fragrance release function prepared in Example 2. Detailed Implementation

[0045] To enable those skilled in the art to fully understand the technical solution and beneficial effects of the present invention, further detailed description is provided below in conjunction with specific embodiments and accompanying drawings. It should be emphasized that the embodiments listed below are merely preferred embodiments of the present invention and do not constitute a limitation thereof. Any simple improvements made based on these embodiments will fall within the protection scope of the present invention.

[0046] To avoid obscuring the invention with unnecessary details, the following embodiments only illustrate raw materials, methods, and steps closely related to the technical solutions of the present invention, while omitting other conventional details. The term "comprising / including" in this invention indicates the presence of a feature, element, step, or component, but does not exclude the presence or addition of one or more other features, elements, steps. Unless otherwise specified, all raw materials mentioned in this invention are commercially available, and all units of measurement are SI units.

[0047] Example 1 This embodiment yields a cyclodextrin-g-PNIPAM (CD-PN) nanocarrier loaded with cinnamaldehyde (CA) (abbreviated as CD-PN@CA), which can be used for intelligent antibacterial finishing of cotton fabrics. The preparation method of this nanocarrier includes carrier synthesis, loading with antibacterial agents, and fabric finishing, as detailed below: (1) Carrier synthesis.

[0048] Under nitrogen protection, pre-dried and dehydrated β-cyclodextrin (1 mmol, 1.13 g), anhydrous DMF (100 mL), and triethylamine (12 mmol, 1.21 g) were added to a 500 mL three-necked flask. The mixture was magnetically stirred for 30 min to ensure complete dissolution and homogeneity of the β-cyclodextrin. The flask was then placed in an ice-water bath to cool to below 5 °C, and while maintaining stirring, 2-bromoisobutyryl bromide (12 mmol, 2.32 g) was added dropwise through a constant-pressure dropping funnel. After the addition was complete, stirring was continued in the ice-water bath for approximately 1 h, followed by heating to 20 °C and maintaining the temperature for approximately 24 h. After the acylation reaction was complete, the reaction solution was poured into 200 mL of ice water, stirred, and a white precipitate was formed. After standing for 12 h, the precipitate was filtered, collected, and washed three times (50 mL each time) with deionized water, followed by two washes (30 mL each time) with anhydrous ethanol to remove unreacted acylation reagents and acid-binding agents. The washed precipitate was placed in a rotary evaporator and the residual solvent was removed by rotary evaporation at 60°C and 0.08 MPa. The solid product was then transferred to a recrystallization apparatus, and anhydrous ethanol was added for recrystallization. After cooling and crystallization, the product was filtered, and the resulting solid was vacuum dried at 80°C for approximately 24 hours to obtain a white powdery macromolecular initiator, β-cyclodextrin-Br. Calculations show that the yield of β-cyclodextrin-Br is approximately 82%.

[0049] The macromolecular initiator β-cyclodextrin-Br (1 mmol, 0.14 g), NIPAM (25 mmol, 2.85 g), and anhydrous THF (80 mL) were added to a 250 mL three-necked flask and magnetically stirred for 15 min to completely dissolve the reactants, obtaining a mixture. The mixture in the three-necked flask was subjected to freeze-thaw cycles for deoxygenation to completely remove oxygen from the system. Specifically, the mixture was first frozen at a low temperature (e.g., -50°C to -80°C) for approximately 5–20 min, followed by thawing with nitrogen gas. This freeze-thaw cycle was repeated multiple times (e.g., 3 times). After deoxygenation, the catalyst CuBr (0.25 mmol, 0.036 g) and the ligand PMDETA (0.25 mmol, 0.044 g) were rapidly added to the three-necked flask, and the mixture was magnetically stirred for approximately 5 min to ensure complete complexation. Maintaining a nitrogen atmosphere, the three-necked flask was heated to 70°C and stirred at this temperature for 6 hours. The ATRP polymerization reaction was then terminated by rapidly immersing the flask in liquid nitrogen for 5 minutes. The reaction solution was transferred to a dialysis bag and dialyzed with deionized water for 72 hours, changing the deionized water every 12 hours. Unreacted monomers, catalysts, and ligands were removed from the product through dialysis. After dialysis, the dialysate was freeze-dried at -50°C and 0.01 MPa for 24 hours to obtain a white, fluffy cyclodextrin-based thermosensitive nanocarrier.

[0050] The test results show that the particle size of the cyclodextrin-based thermosensitive nanocarrier is about 100-200 nm, the low critical solution temperature (LCST) is 32 °C, and the yield is about 78%.

[0051] (2) Loaded with antibacterial agent.

[0052] 2g of cyclodextrin-based thermosensitive nanocarrier was added to 10mL of deionized water at 10℃ (32℃ lower than its LCST temperature) and magnetically stirred for 2h to fully dissolve it, resulting in a carrier solution with a mass fraction of 20%.

[0053] 10g of silver nanoparticle aqueous dispersion (containing 1g of silver nanoparticles) was slowly added dropwise to the above carrier solution. After the addition was completed, the mixture was stirred at 10℃ for 9 hours to allow the silver nanoparticles to be fully loaded onto the nanocarrier through host-guest inclusion interaction (i.e., the hydrophobic cavity of β-cyclodextrin is combined with the hydrophobic surface of the silver nanoparticles).

[0054] The mixture was transferred to a dialysis bag and dialyzed for 24 hours using deionized water as the dialysis medium to remove unloaded free silver nanoparticles. After dialysis, the dialysate was freeze-dried for 24 hours to obtain a gray powder-like thermosensitive responsive nanocarrier loaded with antibacterial agent (silver nanoparticles).

[0055] Calculations show that the loading rate of the nanocarrier is approximately 16.7% (loading rate = mass of loaded silver nanoparticles / total mass of nanocarrier), and the mass ratio of the cyclodextrin-based thermosensitive nanocarrier to the antibacterial agent is approximately 5:1.

[0056] (3) Fabric finishing.

[0057] A thermosensitive nanocarrier loaded with an antibacterial agent was introduced into the fabric matrix using an impregnation method. The specific process is as follows: 0.5 g of the antibacterial agent-loaded nanocarrier was added to 50 mL of deionized water and ultrasonically dispersed for 30 min to obtain a uniform dispersion. A 10 cm × 10 cm sample was cut from a prepared pure cotton woven fabric and immersed in the dispersion. The bath ratio was controlled at 1:50 (fabric mass g: dispersion volume mL), the impregnation temperature was 25℃, and the impregnation time was 2 h. The mixture was stirred every 30 min to ensure uniform adsorption of the nanocarrier onto the fabric surface. After impregnation, the fabric was removed, and the unadsorbed nanocarriers on the surface were gently rinsed with deionized water. It was then dried in a 60℃ oven for 30 minutes, followed by curing in a 100℃ oven for 1 hour. After natural cooling to room temperature, a thermo-responsive antibacterial fabric loaded with cyclodextrin was obtained. The mass ratio of the loaded thermo-responsive nanocarriers to the fabric matrix was approximately 1:10.

[0058] This antibacterial fabric exhibits excellent temperature-sensitive response. When the ambient temperature is above 32°C (near human body temperature), the nanocarrier slowly releases silver nanoparticles to exert its antibacterial effect. When the temperature is below 32°C, the release rate of silver nanoparticles decreases significantly, thereby achieving intelligent controlled release of the antibacterial agent.

[0059] The antibacterial properties of the antibacterial fabric and the original pure cotton fabric (control group) were tested according to the standard. The results showed that the antibacterial fabric had almost no antibacterial function compared to the original pure cotton fabric. The antibacterial fabric had an inhibition rate of ≥99% against Escherichia coli and Staphylococcus aureus. After 10 washes, the inhibition rate was still ≥95%. Moreover, the breathability and softness of the fabric were basically the same as those of the original pure cotton fabric. There was no obvious hardening or discoloration, which met the requirements for fabric use.

[0060] Example 2 This embodiment yields a pentaerythritol nanocarrier loaded with menthol fragrance, which can be used for leather finishing and imparts thermosensitive fragrance release function. The preparation method of this nanocarrier includes carrier synthesis, fragrance loading, and leather finishing, as detailed below: (1) Carrier synthesis.

[0061] Under argon protection, pre-dried and dehydrated pentaerythritol (1 mmol, 0.14 g), anhydrous DMSO (25 mL), and pyridine (10 mmol, 0.79 g) were added to a 50 mL three-necked flask. The mixture was magnetically stirred for 20 min until the pentaerythritol was completely dissolved. The flask was then placed in an ice-water bath to cool to approximately 0 °C. While maintaining stirring, 2-bromopropionyl bromide (10 mmol, 2.16 g) was added dropwise through a constant-pressure dropping funnel. After the addition was complete, stirring in the ice-water bath continued for about 30 min, followed by heating to 15 °C and reacting at this temperature for about 30 h. After the acylation reaction was complete, the reaction solution was poured into 150 mL of ice water, stirred, and a pale yellow precipitate was formed. The precipitate was collected by filtration and washed four times with deionized water (40 mL each time), followed by two washes with ethyl acetate (20 mL each time). The washed precipitate was placed in a rotary evaporator and the residual solvent was removed by rotary evaporation at 70 °C and 0.08 MPa. The solid product was then transferred to an 80°C oven and vacuum dried for 12 hours to obtain a pale yellow powdery macromolecular initiator, pentaerythritol-Br. Calculations showed that the yield of pentaerythritol-Br was approximately 79%.

[0062] The macromolecular initiator pentaerythritol-Br (1 mmol, 0.16 g), NVCL (15 mmol, 2.09 g), and anhydrous NMP (60 mL) were added to a 250 mL three-necked flask. The mixture was magnetically stirred for 10 min to completely dissolve the reactants, resulting in a mixture. Following the method described in Example 1, the mixture in the three-necked flask was subjected to a freeze-thaw cycle for deoxygenation. Then, the catalyst CuCl (0.15 mmol, 0.015 g) and the ligand TPMA (0.15 mmol, 0.042 g) were rapidly added, and the mixture was stirred for 5 min to form a homogeneous complex system. Under a nitrogen atmosphere, the three-necked flask was heated to 65 °C and stirred at this temperature for 4 h. The ATRP polymerization reaction was then terminated by rapidly immersing the three-necked flask in liquid nitrogen for approximately 5 min. The reaction mixture was transferred to a dialysis bag and dialyzed with deionized water for 48 h, with the deionized water replaced every 8 h, to remove unreacted monomers and catalyst. After dialysis, the dialysate was placed in a freeze dryer and freeze-dried at -50℃ and 0.01MPa for 24 hours to obtain a white powdery pentaerythritol-based thermosensitive nanocarrier.

[0063] The dynamic mechanical light scattering analysis results of the above pentaerythritol-based thermosensitive nanocarriers are as follows: Figure 1 As shown in the figure, the particle size of this pentaerythritol-based thermosensitive nanocarrier is approximately 20-100 nm.

[0064] Transmission electron microscopy (TEM) images of the above pentaerythritol-based thermosensitive nanocarriers are shown below. Figure 2As shown in the figure, the morphology of this pentaerythritol-based thermosensitive nanocarrier is that of nanospheres. Other test results indicate that the LCST temperature of this nanocarrier is 35 °C, and the yield is approximately 76%.

[0065] (2) Loaded with fragrance.

[0066] 1 g of pentaerythritol-based thermosensitive nanocarrier was added to 10 mL of deionized water at 5 °C (35 °C below the LCST temperature) and magnetically stirred for 1.5 h to dissolve it completely, resulting in a carrier solution with a mass fraction of 10%.

[0067] 0.25 g of menthol was dissolved in 2 mL of anhydrous ethanol, and the resulting menthol solution was slowly added dropwise to the above-mentioned carrier solution. After the addition was complete, the mixture was stirred at 5 °C for 6 h to allow the menthol to be fully loaded into the hydrophobic region of the nanocarrier through hydrophobic interactions.

[0068] The mixture was transferred to a dialysis bag and dialyzed for 18 hours using deionized water as the dialysis medium to remove unloaded free menthol and ethanol solvent. After dialysis, the dialysate was freeze-dried for 24 hours to obtain a white powdery thermosensitive menthol-loaded nanocarrier.

[0069] Calculations show that the loading rate of the nanocarrier is about 20%, and the mass ratio of the pentaerythritol-based thermosensitive nanocarrier to menthol is about 4:1.

[0070] The above-mentioned dynamic mechanical light scattering analysis results of the thermosensitive nanocarrier loaded with menthol are as follows: Figure 3 As shown in the figure, the particle size of the pentaerythritol-based thermosensitive nanocarrier loaded with menthol is approximately 100-500 nm, which is a significant increase compared to the particle size before loading, indicating that menthol was successfully loaded.

[0071] TEM images of the above-mentioned thermo-responsive nanocarriers loaded with menthol are shown below. Figure 4 As shown in the figure, its morphology is observed to be nanospheres.

[0072] (3) Preparation of leather coating.

[0073] A coating method was used to introduce menthol-loaded nanocarriers into leather coatings. The specific process is as follows: 100g of waterborne polyurethane resin, 5g of menthol-loaded thermo-responsive nanocarriers, 10g of beige color paste, 1g of dispersant (sodium hexametaphosphate), 0.5g of defoamer (silicone defoamer), and 20g of deionized water were mixed and stirred at high speed for 30min, followed by ultrasonic dispersion for 20min to obtain a uniform coating slurry. A coating slurry without nanocarriers but with only menthol added (i.e., using an equal amount of menthol to replace the menthol-loaded thermo-responsive nanocarrier) was prepared as a blank control group for coating. The prepared cow leather was laid flat on the coating table, and the coating slurry was uniformly coated onto the leather surface using a spray gun, with the coating thickness controlled between 30-50μm. After coating, the cow leather was transferred to an oven and pre-baked at 120℃ for 1-2min, followed by natural cooling to room temperature to obtain the desired result. Figure 5-6 The leather coating shown has a temperature-sensitive fragrance release function.

[0074] The leather coating based on a thermo-responsive nanocarrier loaded with menthol exhibits excellent thermo-responsive aroma release performance. When the ambient temperature is above 35℃, the structure of the nanocarrier changes, rapidly releasing menthol to produce a fresh and cool aroma, with a release duration of ≥8 hours. When the temperature is below 35℃, the aroma release amount decreases significantly, thus achieving intelligent controlled release of the aroma. In contrast, the control group leather coating does not have thermo-responsive aroma release function, only releasing aroma continuously for a short period of time, and is basically unaffected by temperature.

[0075] The leather with temperature-sensitive fragrance release function was tested in accordance with standards such as GB / T 13312-2009. The results showed that the coating was firmly bonded to the leather substrate, with an adhesion level of 1; the coating had good abrasion resistance, with no obvious color fading or peeling after 500 dry rubbing cycles; and the coating had good flexibility and did not affect the feel and breathability of the leather.

[0076] Example 3 This embodiment yields a cellulose nanocrystal nanocarrier loaded with PEG-4000, which can be used for temperature regulation in insole materials. The preparation method of this nanocarrier includes carrier synthesis, loading with phase change materials, and insole fabrication, as detailed below: (1) Carrier synthesis.

[0077] Under nitrogen protection, pre-dried and dehydrated cellulose nanocrystals (1 mmol, 0.162 g), anhydrous THF-DMF mixed solvent (120 mL), and potassium carbonate (12 mmol, 1.66 g) were added to a 500 mL three-necked flask. The mixture was magnetically stirred for 40 min to ensure uniform dispersion of the cellulose nanocrystals in the solvent. The flask was then placed in an ice-water bath to cool to 0–5 °C. α-Bromophenylacetyl bromide (12 mmol, 3.34 g) was added dropwise with stirring. After the addition was complete, stirring in the ice-water bath continued for 1 h. Subsequently, the mixture was heated to 25 °C and reacted at this temperature for 28 h. After the acylation reaction was completed, the reaction solution was poured into 250 mL of ice water, stirred, and a white precipitate was formed. After standing for 8 h, the precipitate was filtered, collected, and washed three times with deionized water (60 mL each time), followed by two washes with acetone (40 mL each time) to remove unreacted reagents. The washed precipitate was placed in a rotary evaporator and the residual solvent was removed by rotary evaporation at 60°C and 0.08 MPa. Then, it was vacuum dried at 80°C for 24 h to obtain the white, flocculent macromolecular initiator CNC-Br. Calculations show that the yield of CNC-Br is approximately 80%.

[0078] The macromolecular initiator CNC-Br (1 mmol, 0.15 g), MEO2MA (40 mmol, 8.88 g), and anhydrous toluene (70 mL) were added to a 250 mL three-necked flask and magnetically stirred for 20 min to ensure uniform dispersion and dissolution of the reactants. Following the method described in Example 1, the mixture in the three-necked flask was subjected to freeze-thaw cycles for deoxygenation. Then, the catalyst PPh3 (0.4 mmol, 0.105 g) and the ligand TREN (0.4 mmol, 0.043 g) were rapidly added and stirred for 10 min to form a stable catalytic system. Maintaining a nitrogen atmosphere, the three-necked flask was heated to 80 °C and stirred at this temperature for 8 h. The ATRP polymerization reaction was then terminated by rapidly immersing the three-necked flask in liquid nitrogen for 5 min. The reaction solution was transferred to a dialysis bag and dialyzed with deionized water for 72 h, with the deionized water replaced every 12 h to remove unreacted monomers, catalysts, and ligands. After dialysis, the cells were freeze-dried for 24 hours to obtain a white powdery cellulose nanocrystal-based thermosensitive nanocarrier.

[0079] The test results show that the particle size of the nanocarrier is about 120-250 nm, the LCST temperature is 38 °C, and the yield is about 77%.

[0080] (2) Loading phase change material.

[0081] 2g of cellulose nanocrystal-based thermosensitive nanocarrier was added to 10mL of deionized water at 0℃ (38℃ below LCST), ultrasonically dispersed for 30min, and then magnetically stirred for 2h to obtain a carrier dispersion with a mass fraction of 16.7%.

[0082] 4g of PEG-4000 (preheated to 50℃ to melt it into a liquid) was slowly added dropwise to the above carrier dispersion. After the addition was completed, the mixture was stirred at 0℃ for 12h to allow it to be loaded onto the surface of the nanocarrier through physical adsorption.

[0083] The mixture was transferred to a dialysis bag and dialyzed for 24 hours using deionized water as the dialysis medium to remove unloaded free PEG-4000. After dialysis, the dialysate was freeze-dried for 24 hours to obtain a white, blocky thermosensitive nanocarrier loaded with phase change material, which was then pulverized to obtain a powdered product.

[0084] Calculations show that the loading rate of the nanocarrier is about 66.7%, and the mass ratio of the cellulose nanocrystal-based thermosensitive responsive nanocarrier to the phase change material is about 1:2.

[0085] (3) Insole preparation.

[0086] 7.14 g of a temperature-sensitive responsive nanocarrier loaded with phase change material was added to 100 g of EVA foam material. The resulting mixture was then fed into a high-speed mixer and blended at 100 °C and 300 r / min for 30 min to ensure uniform dispersion of the nanocarrier within the EVA matrix. The blend was then transferred to a mold and hot-pressed at 150 °C and 10 MPa for 15 min. After cooling to room temperature, the material was demolded to obtain a temperature-sensitive, temperature-regulating shoe material sample supported on cellulose nanocrystals.

[0087] Test results show that the nanocarriers are uniformly dispersed in the EVA matrix without obvious agglomeration. The compressive strength of this shoe material is ≥1.5MPa, and the resilience is ≥40%, meeting the requirements for use in shoe midsoles.

[0088] The temperature regulation range of this shoe material is 35-45℃, which perfectly matches the comfortable temperature requirements of human feet. When the ambient temperature is above 38℃, the nanocarrier releases the loaded PEG-4000, which absorbs heat and melts to achieve cooling; when the temperature is below 38℃, the PEG-4000 releases heat and solidifies to achieve heating. These results demonstrate that the shoe material has excellent temperature-sensitive regulation performance.

Claims

1. A method for preparing a thermo-responsive nanocarrier based on a biomass core, characterized in that... The method includes: mixing biomass material with an acylation reagent to carry out an acylation reaction to obtain a macromolecular initiator; mixing the macromolecular initiator with a thermosensitive vinyl monomer to carry out an ATRP reaction to obtain a thermosensitive responsive nanocarrier; wherein the biomass material contains at least one hydroxyl group, and the acylation reagent is a bromine-substituted organic compound.

2. The method as described in claim 1, characterized in that: The biomass material is selected from at least one of α-cyclodextrin, β-cyclodextrin, γ-cyclodextrin, pentaerythritol, trimethylolpropane, xylitol, sorbitol, cellulose nanocrystals, and partially deacetylated chitosan; the acyl bromide is selected from at least one of 2-bromoisobutyryl bromide, 2-bromopropionyl bromide, α-bromophenylacetyl bromide, 2-bromoisobutyric anhydride, and 2-bromopropionic anhydride; and the thermosensitive vinyl monomer is selected from at least one of N-isopropylacrylamide, N-ethylacrylamide, N,N-diethylacrylamide, N-vinylcaprolactam, and 2-(2-methoxyethoxy)ethyl methacrylate.

3. The method as described in claim 1, characterized in that... The specific process of the acylation reaction includes: mixing biomass materials, solvent A, and acid-binding agent evenly under an inert atmosphere; placing the mixture in an ice-water bath and adding the acylation reagent dropwise; continuing to stir in the ice-water bath after the addition is complete; heating the resulting mixture to carry out the acylation reaction; and separating and purifying the product by means of extraction, rotary evaporation, and recrystallization after the reaction to obtain a macromolecular initiator.

4. The method as described in claim 3, characterized in that: The molar ratio of biomass material, acylation reagent, and acid-binding agent required for the acylation reaction is 1:10-15:10-15, the acylation reaction temperature is 15-25℃, and the reaction time is more than 24 hours; the solvent A is selected from at least one of N,N-dimethylformamide, dimethyl sulfoxide, and tetrahydrofuran, and the acid-binding agent is selected from at least one of triethylamine, pyridine, and potassium carbonate.

5. The method as described in claim 1, characterized in that... The specific process of the ATRP reaction includes: adding a macromolecular initiator and a thermosensitive vinyl monomer to solvent B; after the resulting mixture is subjected to freeze-thaw cycle deoxygenation treatment, adding a catalyst and ligand and mixing them evenly; heating in an inert atmosphere to carry out the ATRP reaction; terminating the reaction by freezing; and purifying the product by dialysis and freeze-drying to obtain a thermosensitive responsive nanocarrier.

6. The method as described in claim 5, characterized in that... The specific process of the freeze-thaw cycle deoxygenation treatment includes: freezing the mixture at a low temperature of -50℃ to -80℃ for 5-20 minutes, thawing it by introducing nitrogen gas, and repeating the freeze-thaw cycle multiple times; the molar ratio of the macromolecular initiator and the thermosensitive vinyl monomer required for the ATRP reaction is 1:10-40, the ATRP reaction temperature is 60-80℃, and the inert atmosphere required for the ATRP reaction is specifically nitrogen or argon atmosphere; the solvent B is selected from at least one of tetrahydrofuran, dimethyl sulfoxide, N-methylpyrrolidone, and toluene; the catalyst is selected from at least one of cuprous bromide, cuprous chloride, and triphenylphosphine; and the ligand is selected from at least one of N,N,N,N,N-pentamethyldiethylenetriamine, tris(2-pyridylmethyl)amine, tris(2-aminoethyl)amine, and diethylenetriamine.

7. The method as described in claim 1, characterized in that... The method further includes: adding a thermo-responsive nanocarrier to a solvent below its LCST temperature to obtain a carrier solution; adding a functional reagent to the carrier solution; separating the resulting mixture by dialysis and freeze-drying to obtain a supported thermo-responsive nanocarrier; and using a mixing method including liquid-liquid mixing, liquid-solid mixing, and solid-solid mixing to introduce the supported thermo-responsive nanocarrier into a matrix material and disperse it uniformly to obtain a thermo-responsive composite functional material.

8. The method as described in claim 7, characterized in that: The mass ratio of thermo-responsive nanocarrier to functional reagent is 1:0.2-2, and the mass ratio of loaded thermo-responsive nanocarrier to matrix material is 1:1-20. The functional reagent is selected from at least one of antibacterial agents, fragrances, phase change materials, dyes, and waterproofing agents, and the matrix material is selected from at least one of textile fibers, leather, and footwear polymer materials.

9. A thermo-responsive nanocarrier, a supported thermo-responsive nanocarrier, or a thermo-responsive composite functional material, characterized in that: The nanocarrier or composite functional material is prepared according to any one of claims 1-8.

10. The application of the thermo-responsive nanocarrier or loaded thermo-responsive nanocarrier or thermo-responsive composite functional material as described in claim 9 in the preparation of smart textiles, smart leather products, and smart footwear materials.

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