A high specific surface area nanocellulose cotton pulp, its preparation method and application

Abstract

This invention discloses a high specific surface area nanocellulose cotton pulp, its preparation method, and its application, belonging to the field of nanocellulose technology. The preparation method includes the following steps: cotton cellulose nanofibers are ultrasonically dispersed in water to obtain a cellulose dispersion; POSSPEGNH2 is added and stirred evenly; aldehyde-based biomaterials are added, and stirring and dispersion are continued. The system is adjusted to a weakly acidic state to obtain a high specific surface area nanocellulose cotton pulp. During the preparation process, POSSPEGNH2 is introduced into the cotton pulp system through synergistic ultrasonic dispersion, and reacts with the aldehyde groups provided in the system to form a dynamic imine crosslinking network, laying the foundation for the good mechanical properties of the cellulose membrane. Nanocellulose membranes prepared using the above-mentioned high specific surface area nanocellulose cotton pulp not only possess good mechanical strength but also expand their application prospects in flexible optoelectronic device substrate materials.

Description

Technical Field

[0001] This invention belongs to the field of nanocellulose technology, specifically relating to a high specific surface area nanocellulose cotton pulp, its preparation method, and its application. Background Technology

[0002] Cellulose is the most abundant renewable resource on Earth, and cellulose nanofibers (CNFs) are one of its most important derivatives. Cellulose nanofibers are a green material with a series of advantages, including high specific surface area, high mechanical properties, and good thermal stability. They have a diameter of 10-40 nm and a length of a few micrometers, and are made from natural wood fibers through chemical and mechanical processing. Cellulose nanofibers possess high strength, stiffness, a large specific surface area, and an extremely low coefficient of thermal expansion. Cellulose nanofibers can be used to create thin films, also known as nanocellulose membranes, through a suction filtration process. Nanocellulose membranes possess a variety of unique properties, including optical transparency, thermal stability, flexibility, printability, high mechanical strength, and strong chemical modification capabilities. Transparent films prepared from nanocellulose materials have advantages such as low cost, biodegradability, lightweight, and foldability, making them a novel sustainable substrate material for flexible electronic devices.

[0003] Currently, cellulose nanofibers are mainly prepared using acid hydrolysis, oxidation, and mechanical homogenization. However, these methods suffer from drawbacks such as high pollution or high energy consumption. Oxidation and mechanical homogenization utilize the selective oxidation of the C6 primary hydroxyl group in cellulose to generate a carboxyl group, giving the cellulose surface a negative charge and creating electrostatic repulsion, thus promoting the separation of cellulose fibers. However, this method still has significant technical limitations: on the one hand, the hydroxyl radicals generated during the oxidation process lead to cellulose degradation, significantly reducing the degree of polymerization of oxidized cellulose; on the other hand, while mechanical homogenization can effectively reduce fiber size and increase membrane density, the resulting transparent cellulose membranes have low strength, far below the mechanical performance requirements for optoelectronic device substrates. More significantly, when these cellulose membranes are heat-treated to adapt to optoelectronic device fabrication processes, their mechanical properties deteriorate further, with a particularly significant decrease in strength at excessively high heat treatment temperatures, severely restricting the practical application of this type of material in the field of optoelectronic devices.

[0004] Therefore, how to significantly improve the mechanical strength of cellulose membranes while maintaining high light transmittance has become a technical challenge that urgently needs to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is, in a first aspect, to provide a method for preparing high specific surface area nanocellulose cotton pulp, laying the foundation for the good mechanical properties of cellulose membranes.

[0006] The second aspect is to provide a high specific surface area nanocellulose pulp, which significantly improves the mechanical strength of cellulose membranes.

[0007] The third aspect provides an application of high specific surface area nanocellulose pulp in the field of optoelectronic devices.

[0008] The objective of this invention can be achieved through the following technical solutions: The first aspect of this invention provides a method for preparing high specific surface area nanocellulose cotton pulp, comprising the following steps: Cotton cellulose nanofibers were ultrasonically dispersed in water to obtain a cellulose dispersion, which was then added to POSS. PEG NH2 was stirred until homogeneous; aldehyde-modified biomaterial was added, and stirring continued to disperse. The weakly acidic pH of the system was adjusted to 5.5-6.0 with 0.1 mol / L HCl to obtain high specific surface area nanocellulose cotton pulp. The weak acidity promotes imine bond formation, enabling POSS... PEG The amino group of NH2 reacts fully with the aldehyde group of aldehyde-modified biomaterials to form dynamic imine bonds, while it may also form hydrogen bonds or hemiacetal structures with the hydroxyl groups of cellulose. Ultrasonic treatment can further increase the specific surface area of ​​the fiber, making it more suitable for applications in optoelectronic devices.

[0009] In some possible implementations, the ultrasonic wave dispersion power is 200-300W, the working time is 2s / interval is 1s, and the total effective ultrasonic time is 15 min. Cotton cellulose nanofibers are obtained by selective oxidation of cotton fibers using TEMPO / NaBr / NaClO. The selective oxidation of cotton cellulose nanofibers using 2,2,6,6-tetramethylpiperidine-1-oxygen radical (TEMPO) / sodium bromide (NaBr) / sodium hypochlorite (NaClO) involves the following steps: Cotton fibers were dispersed in water, TEMPO and NaBr were added and stirred, sodium hydroxide was added to adjust the pH to 10-10.5, and NaClO was added. During the reaction, sodium hydroxide was added to maintain the pH of the system at 10-10.5 for 5-6 hours. After the reaction was completed, anhydrous ethanol was added to terminate the reaction. After washing with water and drying, cotton cellulose nanofibers were obtained.

[0010] The ratio of cotton fiber, TEMPO, NaBr, and NaClO is 5g:0.008g:0.5g:20-25mmol. NaClO is added in the form of a NaClO solution with a mass fraction of 8%-10%.

[0011] In some possible implementations, the cellulose dispersion has a mass fraction of 1%–2%; POSS PEG The amount of NH2 used is 5%–10% of the oven-dry weight of cotton cellulose nanofibers; The aldehyde-based biomaterial is aldehyde-based cellulose, and the amount of aldehyde-based biomaterial used is 5%-10% of the oven-dry weight of oxygen cotton cellulose nanofibers.

[0012] Aldehyde-modified cellulose is prepared by the following steps: Cotton fibers were dispersed in water and sodium periodate was added. The reaction was carried out in the dark. After the reaction was completed, ethylene glycol was added to terminate the reaction and aldehyde-modified cellulose was obtained. The aldehyde content of aldehyde-modified cellulose was about 10-12 mmol / g.

[0013] In some possible implementations, POSS-PEG-NH2 is prepared via the following steps: Mercapto-POSS, amino-polyethylene glycol-allyl, and 2,2-dimethoxy-2-phenylacetophenone were added to dichloromethane and reacted under 365 nm ultraviolet light for 5-6 h. After the reaction was completed, the dichloromethane was removed by concentration under reduced pressure, and the mixture was recrystallized with methyl tert-butyl ether to obtain POSS-PEG-NH2.

[0014] In some possible implementations, the ratio of mercapto-POSS, amino-polyethylene glycol-allyl, and 2,2-dimethoxy-2-phenylacetophenone is 4-5 g: 0.2-0.3 g: 0.05-0.06 g; and the ratio of amino-polyethylene glycol-allyl and dichloromethane is 1 g: 40-50 mL.

[0015] In some possible implementations, mercapto-POSS is prepared by the hydrolytic condensation of γ-mercaptopropyltrimethoxysilane: γ-Mercaptopropyltrimethoxysilane was added to anhydrous methanol, followed by hydrochloric acid solution. The mixture was heated to 85-90℃ and refluxed for 20-24 hours. After the reaction was completed, the mixture was allowed to stand at -20℃ for 16-24 hours. The supernatant was discarded, and the product was added to a mixture of dichloromethane and methanol. The mixture was allowed to stand at -20℃ for 16-24 hours, and the supernatant was discarded. This process was repeated three times to obtain mercapto-POSS. The mass fraction of the hydrochloric acid solution was 37%, and the ratio of γ-mercaptopropyltrimethoxysilane, anhydrous methanol, and hydrochloric acid solution was 11 g: 250-300 mL: 20 mL.

[0016] A second aspect of the present invention provides a high specific surface area nanocellulose cotton pulp, which is prepared by the above-described preparation method.

[0017] A third aspect of this invention provides an application of high specific surface area nanocellulose cotton pulp in the field of optoelectronic devices.

[0018] In some possible implementations, high specific surface area nanocellulose cotton pulp is diluted to a solid content of 0.5%–0.8%, cast into a film, and dried at a temperature of 25–40℃ and a humidity of 40%–50% to obtain a nascent membrane; an ionic liquid is brushed onto the surface of the nascent membrane, and then hot-pressed (hot-pressing temperature of 50–60℃, pressure of 3.5–4 MPa, and time of 6–10 min) to obtain a nanocellulose membrane.

[0019] In some possible implementations, the ionic liquid comprises 1-aminopropyl-3-methylimidazolium bromide and N-ethylimidazolium hydrogen phosphite. The molar ratio of 1-aminopropyl-3-methylimidazolium bromide to N-ethylimidazolium hydrogen phosphite is 1:1-2. The presence of an amino group in 1-aminopropyl-3-methylimidazolium bromide allows it to participate in imine bond formation, further enhancing its performance.

[0020] N-Ethylimidazolium hydrogen phosphite is obtained by reacting N-ethylimidazolium and dimethyl phosphite in a molar ratio of 1:1.1. N-Ethylimidazolium and dimethyl phosphite are added to tetrahydrofuran and refluxed at 66°C for 24-48 hours under nitrogen protection. After the reaction is completed, N-ethylimidazolium hydrogen phosphite is obtained by washing and drying.

[0021] The beneficial effects of this invention are: This invention provides a high specific surface area nanocellulose cotton pulp, in which aminated cage-type polysilsesquioxane-polyethylene glycol (POSS) is introduced into the cotton pulp system through synergistic ultrasonic dispersion during preparation. PEG NH2) reacts with the aldehyde groups provided in the system to form a dynamic imine crosslinking network, laying the foundation for the good mechanical properties of the cellulose membrane.

[0022] This invention uses the above-mentioned high specific surface area nanocellulose cotton pulp as raw material to prepare nanocellulose membranes. The prepared nanocellulose membranes not only have good mechanical strength, but also overcome the bottleneck of low strength of cellulose membranes in the prior art, thus expanding their application prospects in flexible optoelectronic device substrate materials.

[0023] POSS in this invention PEG In NH2, POSS nanocages serve as rigid nano-reinforcing points. Their inorganic core size is much smaller than the visible light wavelength, allowing for uniform dispersion at the molecular level, significantly improving the tensile strength of the film while avoiding light scattering loss and maintaining high transmittance (>90%). PEG flexible ether segments play a toughening and energy dissipation role; their conformational rearrangement improves elongation at break and bending resistance, enhances film uniformity, and reduces the negative impact of internal defects on optics. Imine dynamic bonds construct a stable three-dimensional cross-linked network, effectively enhancing the connection density between cellulose molecular chains. Furthermore, they endow the material with intelligent properties such as self-healing, thermoplasticity, and pH responsiveness, enabling microcracks to heal under heat treatment. Therefore, this invention achieves high transmittance while also possessing excellent mechanical properties, overcoming the bottleneck of low strength in existing cellulose films and expanding its application prospects in flexible optoelectronic device substrate materials. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] The following is a detailed description of a high specific surface area nanocellulose pulp, its preparation method, and its application, based on embodiments of this application.

[0026] The following is a detailed description with reference to specific examples.

[0027] Preparation Example 1 This preparation example demonstrates the preparation of cotton cellulose nanofibers: Cotton fibers were dispersed in water, and TEMPO and NaBr were added with stirring. Sodium hydroxide was added to adjust the pH to 10, and then NaClO solution was added. Sodium hydroxide was added during the reaction to maintain the pH at 10 for 5 hours. After the reaction was complete, anhydrous ethanol was added to terminate the reaction. After washing with water and drying, cotton cellulose nanofibers were obtained. The molar ratio of cotton fiber, TEMPO, NaBr, and NaClO was 5 g: 0.008 g: 0.5 g: 25 mmol. The mass fraction of the NaClO solution was 10%.

[0028] Preparation Example 2 This preparation example prepares POSS-PEG-NH2: γ-Mercaptopropyltrimethoxysilane was added to anhydrous methanol, followed by hydrochloric acid solution. The mixture was heated to 85°C and refluxed for 20 h. After the reaction was completed, the mixture was allowed to stand at -20°C for 16 h. The supernatant was discarded, and the product was added to a mixture of dichloromethane and methanol. The mixture was allowed to stand at -20°C for 16 h, and the supernatant was discarded. This process was repeated three times to obtain mercapto-POSS. The mass fraction of the hydrochloric acid solution was 37%, and the ratio of γ-mercaptopropyltrimethoxysilane, anhydrous methanol, and hydrochloric acid solution was 11 g: 250 mL: 20 mL.

[0029] Mercapto-POSS, amino-polyethylene glycol-allyl, and 2,2-dimethoxy-2-phenylacetophenone were added to dichloromethane and reacted under 365 nm ultraviolet light for 6 h. After the reaction was completed, the dichloromethane was removed by concentration under reduced pressure, and the mixture was recrystallized with methyl tert-butyl ether to obtain POSS-PEG-NH2. The ratio of mercapto-POSS, amino-polyethylene glycol-allyl, and 2,2-dimethoxy-2-phenylacetophenone was 4 g:0.2 g:0.05 g; the ratio of amino-polyethylene glycol-allyl to dichloromethane was 1 g:50 mL.

[0030] Preparation Example 3 This preparation example prepares POSS-PEG-NH2: Thiol-POSS (same as in Preparation Example 2), amino-polyethylene glycol-allyl, and 2,2-dimethoxy-2-phenylacetophenone were added to dichloromethane and reacted under 365 nm ultraviolet light for 6 h. After the reaction was completed, the dichloromethane was removed by concentration under reduced pressure, and the mixture was recrystallized with methyl tert-butyl ether to obtain POSS-PEG-NH2. The ratio of thiol-POSS, amino-polyethylene glycol-allyl, and 2,2-dimethoxy-2-phenylacetophenone was 5 g: 0.3 g: 0.06 g; the ratio of amino-polyethylene glycol-allyl to dichloromethane was 1 g: 50 mL.

[0031] Preparation Example 4 This preparation example prepares aldehyde-modified cellulose: Weigh 10g of cotton fiber and disperse it in 1L of deionized water. Add sodium periodate, the amount of which is 60% of the oven-dry weight of the cellulose. React in the dark for 8 hours at 40℃. Terminate the reaction by adding 10 mL of ethylene glycol. Wash with deionized water until no iodide ions are detected (AgNO3 detection). Filter and dry to obtain aldehyde-modified cellulose. The aldehyde content of aldehyde-modified cellulose is approximately 10-12 mmol / g.

[0032] Example 1 This invention provides a method for preparing high specific surface area nanocellulose cotton pulp, comprising the following steps: The cotton cellulose nanofibers prepared in Preparation Example 1 were added to water and ultrasonically dispersed to obtain a cellulose dispersion with a mass fraction of 1%. The POSS prepared in Preparation Examples 2-3 was then added. PEG NH2 was stirred until homogeneous; aldehyde-modified cellulose prepared in Preparation Example 4 was added, and stirring was continued to disperse the mixture. The weakly acidic pH of the system was adjusted to 6.0 with 0.1 mol / L HCl to obtain high specific surface area nanocellulose cotton pulp. POSS PEG The amount of NH2 used was 8% of the oven-dry weight of cotton cellulose nanofibers; the amount of aldehyde-modified cellulose used was 8% of the oven-dry weight of oxygenated cotton cellulose nanofibers. The ultrasonic dispersion power was 200W, with a working time of 2s and an interval of 1s, for a total effective ultrasonic time of 15 minutes.

[0033] Example 2 This invention provides a method for preparing high specific surface area nanocellulose cotton pulp, comprising the following steps: The cotton cellulose nanofibers prepared in Preparation Example 1 were added to water and ultrasonically dispersed to obtain a cellulose dispersion with a mass fraction of 1%. The POSS prepared in Preparation Examples 2-3 was then added. PEG NH2 was stirred until homogeneous; aldehyde-modified cellulose prepared in Preparation Example 4 was added, and stirring was continued to disperse the mixture. The weakly acidic pH of the system was adjusted to 6.0 with 0.1 mol / L HCl to obtain high specific surface area nanocellulose cotton pulp. POSS PEG The amount of NH2 used is 5% of the oven-dry weight of cotton cellulose nanofibers; the amount of aldehyde-modified cellulose used is 5% of the oven-dry weight of oxygenated cotton cellulose nanofibers. The ultrasonic dispersion power is 200W, with a working time of 2s and an interval of 1s, for a total effective ultrasonic time of 15 minutes.

[0034] Example 3 This invention provides a method for preparing high specific surface area nanocellulose cotton pulp, comprising the following steps: The cotton cellulose nanofibers prepared in Preparation Example 1 were added to water and ultrasonically dispersed to obtain a cellulose dispersion with a mass fraction of 1%. The POSS prepared in Preparation Example 2 was then added to the dispersion. PEG NH2 was stirred until homogeneous; aldehyde-modified cellulose prepared in Preparation Example 4 was added, and stirring was continued to disperse the mixture. The weakly acidic pH of the system was adjusted to 6.0 with 0.1 mol / L HCl to obtain high specific surface area nanocellulose cotton pulp. POSS PEG The amount of NH2 used was 10% of the oven-dry weight of cotton cellulose nanofibers; the amount of aldehyde-modified cellulose used was 10% of the oven-dry weight of oxygenated cotton cellulose nanofibers. The ultrasonic dispersion power was 200W, with a working time of 2s and an interval of 1s, for a total effective ultrasonic time of 15 minutes.

[0035] Example 4 This invention provides a method for preparing high specific surface area nanocellulose cotton pulp, comprising the following steps: The cotton cellulose nanofibers prepared in Preparation Example 1 were added to water and ultrasonically dispersed to obtain a cellulose dispersion with a mass fraction of 1%. The POSS prepared in Preparation Example 3 was then added to the dispersion. PEG NH2 was stirred until homogeneous; aldehyde-modified cellulose prepared in Preparation Example 4 was added, and stirring was continued to disperse the mixture. The weakly acidic pH of the system was adjusted to 6.0 with 0.1 mol / L HCl to obtain high specific surface area nanocellulose cotton pulp. POSS PEG The amount of NH2 used was 8% of the oven-dry weight of cotton cellulose nanofibers; the amount of aldehyde-modified cellulose used was 8% of the oven-dry weight of oxygenated cotton cellulose nanofibers. The ultrasonic dispersion power was 200W, with a working time of 2s and an interval of 1s, for a total effective ultrasonic time of 15 minutes.

[0036] Comparative Example 1 The difference between this comparative example and Example 1 is that ultrasonic dispersion is not used; only conventional stirring dispersion is used. The other raw materials and preparation process remain the same as in Example 1.

[0037] Comparative Example 2 The difference between this comparative example and Example 1 is that POSS is not added. PEG NH2, and the remaining raw materials and preparation process are the same as in Example 1.

[0038] Comparative Example 3 The difference between this comparative example and Example 1 is that POSS is used. PEG NH2 was replaced with octaaminopropyl cage-like polysilsesquioxane, and the remaining raw materials and preparation process remained the same as in Example 1.

[0039] Example 5 This embodiment provides a nanofiber cellulose membrane, which is prepared by the following steps: The high specific surface area nanocellulose cotton pulp from Example 1 was diluted to a solid content of 0.5%, cast into a film, and dried at 25°C and 40% humidity to obtain a nascent film; an ionic liquid solution (2 g / m³) was then sprayed onto the surface of the nascent film. 2The nanocellulose membrane was obtained by hot pressing (at a temperature of 50°C, a pressure of 3.5 MPa, and a time of 10 min) and then repeatedly washing it in anhydrous ethanol.

[0040] The ionic liquid solution comprises an ionic liquid and ethanol, with a mass fraction of 50%. The ionic liquid consists of 1-aminopropyl-3-methylimidazolium bromide and N-ethylimidazolium hydrogen phosphite. The molar ratio of 1-aminopropyl-3-methylimidazolium bromide to N-ethylimidazolium hydrogen phosphite is 1:2.

[0041] N-Ethylimidazolium hydrogen phosphite was obtained by reacting N-ethylimidazolium and dimethyl phosphite in a molar ratio of 1:1.1. N-Ethylimidazolium and dimethyl phosphite were added to tetrahydrofuran and refluxed at 66°C for 24 hours under nitrogen protection. After the reaction was completed, N-ethylimidazolium hydrogen phosphite was obtained by washing and drying.

[0042] Example 6 The difference between this embodiment and Example 5 is that the high specific surface area nanocellulose cotton pulp is replaced with the high specific surface area nanocellulose cotton pulp prepared in Example 2, while the other raw materials and preparation process remain the same as in Example 5.

[0043] Example 7 The difference between this embodiment and Example 5 is that the high specific surface area nanocellulose cotton pulp is replaced with the high specific surface area nanocellulose cotton pulp prepared in Example 3, while the other raw materials and preparation process remain the same as in Example 5.

[0044] Example 8 The difference between this embodiment and Example 5 is that the high specific surface area nanocellulose pulp is replaced with the high specific surface area nanocellulose pulp prepared in Example 4, while the other raw materials and preparation process remain the same as in Example 5.

[0045] Example 9 The difference between this embodiment and Embodiment 5 is that the primary membrane is obtained by drying at a temperature of 40°C and a humidity of 50%; and an ionic liquid solution (2g / m³) is sprayed onto the surface of the primary membrane. 2 The nanofiber membrane was obtained by hot pressing (60℃, 4MPa, 6min) followed by repeated washing in anhydrous ethanol. Example 10 The difference between this embodiment and Embodiment 5 is that the ionic liquid solution includes an ionic liquid and ethanol, with a mass fraction of 50%. The ionic liquid includes 1-aminopropyl-3-methylimidazolium bromide and N-ethylimidazolium hydrogen phosphite. The molar ratio of 1-aminopropyl-3-methylimidazolium bromide to N-ethylimidazolium hydrogen phosphite is 1:1.

[0046] Comparative Example 4 Compared with Example 5, this comparative example replaces the high specific surface area nanocellulose cotton pulp with the high specific surface area nanocellulose cotton pulp in Comparative Example 1, while the other raw materials and preparation process remain the same as in Example 5.

[0047] Comparative Example 5 Compared with Example 5, this comparative example replaces the high specific surface area nanocellulose cotton pulp in Comparative Example 2 with the high specific surface area nanocellulose cotton pulp, while the other raw materials and preparation process remain the same as in Example 5.

[0048] Comparative Example 6 Compared with Example 5, this comparative example replaces the high specific surface area nanocellulose cotton pulp with the high specific surface area nanocellulose cotton pulp in Comparative Example 3, while the other raw materials and preparation process remain the same as in Example 5.

[0049] Comparative Example 7 Compared with Example 5, this comparative example did not involve spraying an ionic liquid solution, but the remaining raw materials and preparation process remained the same as in Example 5.

[0050] Test case The sample thickness was 50 μm ± 2 μm.

[0051] The transmittance was measured using a spectrophotometer in accordance with GB / T2410-2008, with a wavelength range of 400~800 nm.

[0052] Tensile strength test: Five different sampling points on the sample membrane were randomly selected for measurement. The mechanical properties of the cellulose membrane were determined using a universal testing machine. The tensile speed was 1 mm / min and the load was 100 N. Each sample was tested three times and the average value was taken.

[0053] Performance tests were conducted on Examples 5-10 and Comparative Examples 4-6, and the results are shown in Table 1. Table 1

[0054] As can be seen from Table 1, Examples 5-10 all employed ultrasonic dispersion and POSS. PEG Dynamic crosslinking of NH2 with aldehyde-modified cellulose. Compared with the comparative example, the light transmittance of each embodiment remained at a high level with minimal differences between them, indicating that this technical solution has no significant negative impact on optical performance. Simultaneously, the tensile strength of the embodiments was significantly higher than that of the comparative example, demonstrating the effectiveness of the dynamic imine crosslinking network and POSS. PEG The introduction of NH2 can effectively improve the mechanical properties of cellulose membranes.

[0055] When adding POSS PEG When the amount of NH2 and aldehyde-modified cellulose is adjusted (as in Example 7), the tensile strength shows a further increasing trend, while the light transmittance remains stable, indicating that appropriately increasing the crosslinking density is beneficial for enhancing the effect without impairing optical properties. POSS of different preparation examples PEG The effects of NH2 (Preparation Example 2 and Preparation Example 3) on the final properties are similar, indicating that the synthesis method has good reproducibility.

[0056] The film-forming drying conditions (Example 9) and the ionic liquid ratio (Example 10) have a slight effect on the light transmittance, but the latter has a certain regulating effect on the tensile strength and can be optimized according to actual needs.

[0057] Comparative Example 4 did not use ultrasonic dispersion, resulting in larger cellulose fiber size, looser membrane structure, and decreased light transmittance and tensile strength, indicating that ultrasonic treatment is the basis for achieving high optical and mechanical properties.

[0058] Comparative Example 5 without POSS PEG NH2, relying only on partial crosslinking of aldehyde-modified cellulose, resulted in a limited increase in tensile strength, verifying the POSS. PEG The key role of NH2 in constructing dynamic cross-linked networks.

[0059] Comparative Example 6 will use POSS PEG When NH2 was replaced with rigid octaaminopropyl POSS (without flexible PEG segments), its light transmittance decreased slightly. Although its tensile strength was higher than that of Comparative Example 5, it was still lower than that of Example 5, indicating that the introduction of flexible PEG segments has a positive effect on maintaining excellent optical performance and enhancing mechanical properties.

[0060] In Comparative Example 7, the performance decreased without ionic liquid spraying. This is because ionic liquid spraying combined with hot pressing not only eliminates pores through a dissolution-filling mechanism and promotes the formation of a denser hydrogen bond network between fibers, but also, without this treatment step, the bonding between fibers mainly relies on the original hydrogen bonds and a small amount of imine crosslinking. Insufficient interfacial bonding strength leads to a decrease in overall strength.

[0061] The tensile strength retention rates of the samples prepared in Example 5 and Comparative Examples 4-7 were tested and recorded after aging in air at 100°C for 24 h. The results are shown in Table 2 below: Table 2

[0062] As can be seen from the comparison, the sample prepared by the present invention can still maintain good mechanical properties at this temperature and has good thermal stability.

[0063] It should be noted that, in this document, relational terms such as "first" and "second" are used only to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such process, method, article, or apparatus.

[0064] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for preparing a high specific surface area nanocellulose fluff pulp, characterized by, Includes the following steps: Cotton cellulose nanofibers were added to water and ultrasonically dispersed to obtain a cellulose dispersion. POSS was then added. PEG NH2 was stirred until homogeneous; aldehyde-modified biomaterials were added, and stirring was continued to disperse the mixture. The system was adjusted to be weakly acidic to obtain high specific surface area nanocellulose cotton pulp.

2. The method for preparing high specific surface area nanocellulose cotton pulp according to claim 1, characterized in that, The ultrasonic dispersion power is 200-300W; the cotton cellulose nanofibers are obtained by selective oxidation of cotton fibers using TEMPO / NaBr / NaClO.

3. The method for preparing high specific surface area nanocellulose cotton pulp according to claim 1, characterized in that, The mass fraction of the cellulose dispersion is 1%–2%; POSS PEG The amount of NH2 used is 5%–10% of the oven-dry weight of cotton cellulose nanofibers; The aldehyde-modified biomaterial is aldehyde-modified cellulose, and the amount of aldehyde-modified biomaterial used is 5%-10% of the oven-dry weight of oxygen cotton cellulose nanofibers; the aldehyde content of aldehyde-modified cellulose is about 10-12 mmol / g.

4. The method for preparing high specific surface area nanocellulose cotton pulp according to claim 1, characterized in that, POSS-PEG-NH2 is prepared by the following steps: Mercapto-POSS, amino-polyethylene glycol-allyl, and 2,2-dimethoxy-2-phenylacetophenone were added to dichloromethane and reacted under 365 nm ultraviolet light for 5-6 h. After the reaction was completed, the dichloromethane was removed by concentration under reduced pressure, and the mixture was recrystallized with methyl tert-butyl ether to obtain POSS-PEG-NH2.

5. The method for preparing high specific surface area nanocellulose cotton pulp according to claim 4, characterized in that, The ratio of mercapto-POSS, amino-polyethylene glycol-allyl, and 2,2-dimethoxy-2-phenylacetophenone is 4-5g:0.2-0.3g:0.05-0.06g; the ratio of amino-polyethylene glycol-allyl and dichloromethane is 1g:40-50mL.

6. The method for preparing a high specific surface area nanocellulose cotton pulp according to claim 4, characterized in that, The mercapto-POSS was prepared by the hydrolytic condensation of γ-mercaptopropyltrimethoxysilane.

7. A high specific surface area nanocellulose cotton pulp, characterized in that... Prepared by the preparation method according to any one of claims 1-6.

8. An application of high specific surface area nanocellulose cotton pulp in the field of optoelectronic devices, characterized in that, Nanocellulose membranes are prepared using the high specific surface area nanocellulose cotton pulp as described in claim 7.

9. The application of the high specific surface area nanocellulose cotton pulp according to claim 8 in the field of optoelectronic devices, characterized in that, High specific surface area nanocellulose cotton pulp is diluted to a solid content of 0.5%-0.8%, cast into a film, and dried at a temperature of 25-40℃ and a humidity of 40%-50% to obtain a nascent film. An ionic liquid is brushed onto the surface of the nascent film, and then hot-pressed to obtain a nanocellulose membrane. The hot-pressing temperature is 50-60℃, the pressure is 3.5-4MPa, and the time is 6-10min.

10. The application of the high specific surface area nanocellulose cotton pulp according to claim 9 in the field of optoelectronic devices, characterized in that, The ionic liquid comprises 1-aminopropyl-3-methylimidazolium bromide and N-ethylimidazolium hydrogen phosphite; the molar ratio of 1-aminopropyl-3-methylimidazolium bromide and N-ethylimidazolium hydrogen phosphite is 1:1-2.

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