A method for constructing a super-hydrophobic surface of paper using hemicellulose as a nanoparticle adsorbent

Abstract

The present invention discloses a method for constructing a super-hydrophobic surface of paper using hemicellulose as a nanoparticle adsorbent. The present invention chemically derivatizes hemicellulose extracted from plant fibers in a corresponding solvent at an appropriate solid-liquid ratio to obtain low-surface-energy hemicellulose; while having a low surface energy, the hemicellulose can well anchor inorganic nanoparticles, and also retains the good affinity of natural hemicellulose for paper, and has the advantages of low cost, green environmental protection, and mild preparation conditions; after the hemicellulose is coated on paper, the hemicellulose is used as an adsorbent to adsorb the fully dispersed nanoparticles to the paper surface in a suitable solvent to construct a super-hydrophobic surface. Compared with the known method of using hemicellulose as a dispersant to disperse nanoparticles and coating them on the surface of paper or wood to construct a hydrophobic surface, the paper surface obtains stronger hydrophobic properties and achieves a super-hydrophobic effect (contact angle>150°).

Description

Technical Field

[0001] The invention belongs to the fields of surface physics and chemistry and biomass resource utilization, and particularly relates to a method for constructing a super-hydrophobic surface of paper by using hemicellulose as a nanoparticle adsorbent. Background Art

[0002] As a naturally renewable material, paper fiber is rich in hydrophilic groups and has a well-developed porous structure, making it highly absorbent. However, after absorbing water and swelling, its strength decreases significantly, and its physical properties vary significantly. Despite being a widely used fiber material, its hygroscopicity has always restricted its application in fields such as printing, packaging, and document storage. Therefore, improving the hydrophobic properties of paper materials has become a key development priority to meet the requirements of various product applications.

[0003] Based on the principle of the "lotus effect", biomimetic construction of a hydrophobic surface for paper is a new way to improve the functionality of paper by effectively isolating it from contact with water, thereby giving it excellent properties such as waterproofing, anti-fouling, and self-cleaning. The method of constructing a super-hydrophobic structure on the surface of paper is to form a relatively rough nanostructure on the surface of the paper and modify it with low-surface-energy substances. Mainly through electrochemical deposition, plasma etching and other methods to form a rough micro-nanostructure on the surface of the paper, and then use low-surface-energy substances to modify the paper, such as hydrocarbons or fluorine compounds. Commonly used low-surface-energy substances include long-chain organic silanes such as hexadecyltrimethoxysilane (HDTMS) and octadecyltrichlorosilane (OTS) and fluorinated silanes. Since petroleum-based compound resources are non-renewable, they are not environmentally friendly and are not conducive to paper recycling; at the same time, petroleum-based compounds have poor affinity for paper, so the durability of super-hydrophobic surfaces is low. In order to solve the environmental pollution problem caused by petroleum-based adhesives used to construct superhydrophobic surfaces and the problem of insufficient affinity of petroleum-based compounds to paper, the development of high-performance renewable superhydrophobic surface adhesives is of great significance to the sustainable development of the papermaking industry.

[0004] Hemicellulose, a naturally abundant natural polymer, accounts for approximately 20% to 30% of the dry weight of plant resources. As a high-molecular-weight polysaccharide, hemicellulose possesses excellent molecular reactivity, a suitable molecular weight, and a natural affinity for paper, offering significant potential as a replacement for petroleum-based compounds. However, currently reported methods for creating hydrophobic surfaces by blending modified hemicellulose with nanoparticles and coating them on paper or wood have shown poor surface hydrophobicity, with contact angles falling short of the required superhydrophobic surface (contact angle <150°). Summary of the Invention

[0005] To address the shortcomings and deficiencies of the prior art, the present invention provides a method for constructing a super-hydrophobic surface on paper using hemicellulose as a nanoparticle adsorbent. This method, provided herein, utilizes hemicellulose adsorbed nanoparticles to construct a super-hydrophobic surface on paper. This method utilizes chemically derivatized, low-surface-energy hemicellulose to efficiently adsorb, disperse, and anchor nanoparticles in a suitable solvent, resulting in a highly durable super-hydrophobic surface.

[0006] The purpose of the present invention is achieved through the following technical solutions:

[0007] A method for constructing a super-hydrophobic surface of paper using hemicellulose as a nanoparticle adsorbent comprises the following steps:

[0008] (1) adding hemicellulose extracted from plant fiber raw materials into a solvent system, and adding a chemical derivatization reagent and a catalyst to chemically modify the hemicellulose to obtain chemically derivatized hemicellulose;

[0009] (2) loading the chemically derivatized hemicellulose prepared in step (1) onto paper fibers;

[0010] (3) dispersing the nanoparticles in a solvent to obtain a nanoparticle dispersion, and immersing the paper fibers treated in step (2) into the nanoparticle dispersion to allow the nanoparticles to be deposited and adsorbed on the paper fibers, thereby constructing a superhydrophobic surface.

[0011] The chemically derivatized hemicellulose prepared by the present invention has low surface energy and can well anchor inorganic nanoparticles, while retaining the good affinity of natural hemicellulose for paper, and is low in cost and environmentally friendly.

[0012] Preferably, the plant fiber raw material in step (1) is at least one of corn stalks, bagasse, hardwood, corn cobs and oil tea husks.

[0013] Preferably, the catalyst in step (1) is at least one of 4-dimethylaminopyridine (DMAP), p-toluenesulfonic acid, dimethylaniline, anhydrous sodium acetate, N-bromosuccinimide (NBS), sodium hydroxide, potassium hydroxide, and 2-methylpyridine borane. The amount of the catalyst used is the conventional catalytic amount in the art.

[0014] Preferably, the reaction temperature for chemically modifying hemicellulose in step (1) is 20° C. to 90° C., and the reaction time is 4 to 24 hours.

[0015] Preferably, the chemical derivatization reagent in step (1) is at least one of a long-chain acid anhydride compound, a long-chain halogenated hydrocarbon compound, and a long-chain amine compound; and the molar ratio of the chemical derivatization reagent to hemicellulose is 1:10 to 2:1.

[0016] More preferably, the long-chain acid anhydride compound is at least one of octylsuccinic anhydride, dodecenylsuccinic anhydride, hexadecenylsuccinic anhydride, acetic anhydride, propionic anhydride, nitroanhydride, and valeric anhydride.

[0017] More preferably, the long-chain halogenated hydrocarbon compound is at least one of dodecane bromide, cyclohexane bromide, p-carboxymethylbenzyl bromide, and benzyl bromide.

[0018] More preferably, the long-chain amine compound is at least one of dodecylamine, hexadecylamine and octylamine.

[0019] More preferably, the molar ratio of the chemical derivatization agent to hemicellulose is (2-5):10.

[0020] Preferably, the solvent system in step (1) is at least one of dimethyl sulfoxide, tetrahydrofuran, water, dimethylformamide (DMF) / lithium chloride system, acetate buffer, ionic liquid, and acetone.

[0021] Preferably, the solid-to-liquid ratio of the hemicellulose and the solvent system in step (1) is 1 g:10 mL to 1 g:100 mL; more preferably, 1 g:30 mL to 1 g:50 mL.

[0022] Preferably, the degree of substitution of the chemically derivatized hemicellulose obtained by modification in step (1) is 0.1 to 0.5.

[0023] Preferably, the chemically derivatized hemicellulose in step (2) is first dispersed into a dispersion system and then loaded onto paper fibers; the dispersion system is at least one of water, ethanol, chloroform, water / ethanol, and chloroform / ethanol systems.

[0024] Preferably, the method for loading the chemically derivatized hemicellulose onto the paper fibers in step (2) is at least one of coating, impregnation, chemical vapor deposition, and wet chemical methods.

[0025] Preferably, the nanoparticles in step (3) are at least one of metal nanoparticles, silicon dioxide nanoparticles, silicon nanoparticles, carbon nanotube particles, zinc oxide particles, and titanium dioxide nanoparticles. Experiments have shown that the amount of nanoparticles used has little effect on the hydrophobic effect of the coating, so there is no need to strictly limit the amount of nanoparticles used.

[0026] Compared with the prior art, the present invention has the following advantages and beneficial effects:

[0027] (1) Compared with traditional petroleum-based super-hydrophobic adhesives, the chemically derivatized hemicellulose prepared by the present invention has the advantages of low surface energy, green degradability, simple preparation method, mild preparation conditions, good biocompatibility, and strong affinity for paper. It can be used as a low surface energy compound for constructing a super-hydrophobic surface of paper and as an anchoring agent for nanoparticles on the surface of paper. It can well anchor inorganic nanoparticles, and the constructed super-hydrophobic surface is highly durable.

[0028] (2) The method provided herein for constructing a super-hydrophobic surface on paper by adsorbing hemicellulose nanoparticles can efficiently adsorb, disperse, and anchor nanoparticles in a suitable solvent using low-surface-energy chemically derivatized hemicellulose, forming a nanoscale rough surface and constructing a super-hydrophobic surface on paper with high durability. Compared to previously reported methods for constructing a hydrophobic surface by dispersing nanoparticles on modified hemicellulose and then coating paper or wood, the present invention significantly improves the hydrophobicity of the paper surface, successfully constructing a super-hydrophobic surface.

[0029] (3) The preparation method provided by the present invention effectively utilizes the waste hemicellulose resources in the pulping and papermaking and agricultural and forestry biomass processing industries, realizes the high-value utilization of hemicellulose, provides a new way for the resource utilization of hemicellulose, and has good economic value. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 SEM images of unprocessed filter paper (a), D1 prepared in Comparative Example 1 (b), H1 prepared in Example 1 (c), H2 prepared in Example 2 (d), H3 prepared in Example 3 (e), and H4 prepared in Example 4 (f).

[0031] Figure 2 EDS distribution of adsorbed nano-silica in Example 1 (a), EDS distribution of adsorbed nano-silica in Example 2 (b), EDS distribution of adsorbed nano-silica in Example 3 (c), EDS distribution of adsorbed nano-silica in Example 4 (d), and EDS distribution of adsorbed nano-silica in Comparative Example 1 (e).

[0032] Figure 3 Line graphs of the water contact angles of H1 to H4 prepared in Examples 1-4 and D1 to D4 prepared in Comparative Examples 1-4 and the contact angles after 14 seconds.

[0033] Figure 4 Contact angle water drop image of H1 prepared in Example 1 (a), contact angle water drop image of H2 prepared in Example 2 (b), contact angle water drop image of H3 prepared in Example 3 (c), contact angle water drop image of H4 prepared in Example 4 (d). DETAILED DESCRIPTION

[0034] The present invention will be described in further detail below with reference to the examples and accompanying drawings, but the embodiments of the present invention are not limited thereto. The raw materials involved in the present invention can be purchased directly from the market. For process parameters not specifically noted, conventional techniques can be used.

[0035] Example 1

[0036] (1) 5 g (7.5 mmol dehydrated xylose units) of hemicellulose obtained by alkali extraction was taken and continuously stirred at 60°C in a heated magnetic stirrer to completely dissolve it in 60 ml of DMSO; when the temperature dropped to 50°C, 0.5 g of 4-dimethylaminopyridine (DMAP) and hexadecenylsuccinic anhydride (HDSA, 322.48 g / mol) were added to the system to obtain a mixed solution (HDSA was pre-dissolved in 10 ml of DMSO and slowly added to the system), and the molar ratio of hemicellulose to hexadecenylsuccinic anhydride was 1:0.3; the mixed solution was reacted at 50°C for 6 h with a stirring speed of 500 rpm; after the reaction, the above reaction solution was added into four times its volume of continuously stirred anhydrous ethanol, the stirring was stopped and the solution was allowed to stand overnight, washed and centrifuged, and dried to obtain a long-chain anhydride-modified hemicellulose sample.

[0037] (2) Dissolve the long-chain anhydride-modified hemicellulose in 20 mL of deionized water, draw 3 mL of the solution with a syringe, and evenly coat it on a 12 cm × 10 cm filter paper using a coater. After coating, place it in a 105 ° C oven for a short time to dry. Repeat the coating-drying process three times, and then coat the other side of the filter paper in the same way. After completion, dry it at 105 ° C and place it in a constant temperature and humidity chamber to maintain 25 ° C and 50% humidity. Use a weight to flatten the coated filter paper.

[0038] (3) Nano-silica was dispersed in chloroform to obtain a dispersion (the ratio of nanoparticles to organic solvent was 1 g: 20 mL), the filter paper treated in step (2) was immersed in the dispersion, and the nano-silica was deposited on the filter paper by an immersion method to construct a super-hydrophobic surface, thereby obtaining a long-chain acid anhydride-modified hemicellulose super-hydrophobic filter paper, which was recorded as H1.

[0039] The maximum water contact angle of H1 prepared in Example 1 was 152.3°, demonstrating excellent hydrophobic properties. This angle remained at approximately 151.8° after 14 seconds, and the abrasion resistance was 80 to 100 times. Furthermore, SEM and EDS images revealed a relatively uniform dispersion of the nanosilica on the paper surface after application. Furthermore, the long-chain anhydride-modified hemicellulose prepared in Example 1 had a degree of substitution of 0.271, lowering its surface energy while retaining the hydroxyl groups on the hemicellulose to form hydrogen bonds with the paper, making the superhydrophobic surface more robust.

[0040] Example 2

[0041] (1) 5 g (7.5 mmol dehydrated xylose units) of hemicellulose obtained by DMSO extraction was taken and continuously stirred at 60 ° C in a heated magnetic stirrer to completely dissolve it in a lithium chloride / N, N-dimethylformamide solution with a concentration of 2 wt%. The solid-liquid ratio of hemicellulose and lithium chloride / N, N-dimethylformamide solution was 1 g: 20 mL. Acetic anhydride was added with N-bromosuccinimide (NBS) as a catalyst (the molar ratio of hemicellulose to acetic anhydride was 5:1) and stirred at 50 ° C and 200 rpm for 2 h. After the reaction was completed, the reaction solution was cooled to room temperature. After the reaction was completed, the reaction solution was added into four times its volume of continuously stirred anhydrous ethanol, and the stirring was stopped and the solution was allowed to stand overnight. After washing, centrifugation was performed and the acetylated hemicellulose sample was obtained after drying.

[0042] (2) Acetylated hemicellulose was dissolved in 20 mL of deionized water, and a 12 cm × 10 cm filter paper was immersed in the solution. The paper was taken out and placed in a 105°C oven for a short drying. The immersion-drying process was repeated three times. After the paper was dried at 105°C, it was placed in a constant temperature and humidity chamber to maintain 25°C and 50% humidity. The coated filter paper was then flattened with a weight.

[0043] (3) Nano-silica was dispersed in a water / ethanol solution to obtain a dispersion (the ratio of nanoparticles to solvent was 1 g: 20 mL), and the filter paper treated in step (2) was immersed in the dispersion. Nano-silica nanoparticles were adsorbed onto the filter paper by an immersion method to construct a super-hydrophobic surface, thereby obtaining acetylated hemicellulose super-hydrophobic filter paper, which was recorded as H2.

[0044] The H2 sample prepared in Example 2 achieved a maximum water contact angle of 151.84° and remained stable at 150.23° after 14 seconds, demonstrating good stability and abrasion resistance of 90 to 120 times. Its hydrophobicity met the requirements for superhydrophobicity, and SEM and EDS images showed that the nanosilica was evenly distributed on the filter paper fiber surface. The acetylated hemicellulose prepared in Example 2 had a degree of substitution of 0.266, which lowered its surface energy while retaining the hydroxyl groups on the hemicellulose to form hydrogen bonds with the paper, making the superhydrophobic surface more robust.

[0045] Example 3

[0046] (1) 5 g (7.5 mmol of dehydrated xylose units) of hemicellulose obtained by alkali extraction was taken and stirred continuously at 60°C in a heated magnetic stirrer to completely dissolve it in 60 ml of alkaline aqueous solution (sodium hydroxide was used as a catalyst), and a certain amount of bromododecane (the molar ratio of hemicellulose to bromododecane was 1:0.5) was added to obtain a mixed solution; the mixed solution was reacted at 50°C for 5 h with a stirring speed of 500 rpm; after the reaction, the above reaction solution was added into four times its volume of continuously stirred anhydrous ethanol, the stirring was stopped and the solution was allowed to stand overnight, washed, centrifuged, and dried to obtain a halogenated hemicellulose sample.

[0047] (2) Dissolve the halogenated hemicellulose in 20 mL of deionized water, and dip a 12 cm × 10 cm filter paper into the hemicellulose solution. Then, briefly dry it in an oven at 105 °C. Repeat the dipping-drying process three times. After drying at 105 °C, place it in a constant temperature and humidity chamber to maintain 25 °C and 50% humidity. Press the coated filter paper flat with a weight.

[0048] (3) Nano-silica was dispersed in anhydrous ethanol to obtain a dispersion (the ratio of nanoparticles to solvent was 1 g: 20 mL), the filter paper treated in step (2) was immersed in the dispersion, and the nano-silica nanoparticles were adsorbed onto the filter paper by a coating method using a coating machine to construct a super-hydrophobic surface, thereby obtaining a halogenated etherified modified hemicellulose super-hydrophobic filter paper, which was recorded as H3.

[0049] The H3 sample prepared in Example 3 achieved a maximum contact angle of 151.27°, and after 14 seconds, the contact angle was 151.15°, achieving comfortable superhydrophobic conditions. It also exhibited good stability, with a wear resistance of 80 to 110 times. SEM and EDS images revealed excellent dispersion of nanosilica on the paper fiber surface. The halide-derivatized hemicellulose prepared in Example 3 had a degree of substitution of 0.350, lowering its surface energy while retaining the hydroxyl groups on the hemicellulose to form hydrogen bonds with the paper, making the superhydrophobic surface more robust.

[0050] Example 4

[0051] (1) 5 g (7.5 mmol of dehydrated xylose units) of hemicellulose extracted with DMSO was completely dissolved in 250 mL of acetate buffer (0.1 mol / L, pH = 4.5) by continuous stirring at 60°C in a heated magnetic stirrer and stirred for 30 min. Dodecylamine (dissolved in anhydrous ethanol) and catalyst 2-methylpyridine borane were then added, wherein the molar ratio of hemicellulose to dodecylamine was 1:0.2. The reaction was carried out at 50°C for 12 h. After the reaction was completed, the reaction solution was added to four times its volume of continuously stirred anhydrous ethanol, and the stirring was stopped and the solution was allowed to stand overnight. After washing, the solution was centrifuged and dried to obtain a reductively aminated hemicellulose sample.

[0052] (2) Dissolve the reductively aminated modified hemicellulose in 20 mL of deionized water, draw 3 mL of the solution with a syringe, and evenly apply it to a 12 cm × 10 cm filter paper by spraying. After coating, place it in a 105 ° C oven for a short time to dry. Repeat the spray-drying three times, and then coat the other side of the filter paper in the same way. After completion, place it in a 105 ° C oven for drying and then place it in a constant temperature and humidity chamber to maintain 25 ° C and 50% humidity. Flatten the coated filter paper with a weight;

[0053] (3) Nano-silica was dispersed in chloroform / ethanol solvent to obtain a dispersion (the ratio of nanoparticles to solvent was 1 g: 20 mL), and the filter paper treated in step (2) was immersed in the dispersion. Nano-silica nanoparticles were adsorbed onto the filter paper by an immersion method to construct a super-hydrophobic surface, thereby obtaining a reductively aminated modified hemicellulose super-hydrophobic filter paper, which was recorded as H4.

[0054] The water contact angle of sample H4 prepared in Example 4 reached 157.05°, and the contact angle after 14 seconds still reached 152.56°, achieving a superhydrophobic effect. It also had good stability and a wear resistance of 80 to 100 times. SEM and EDS images show that the nanosilica is evenly distributed on the surface of the paper fibers and has a high adsorption capacity. The reductively aminated modified hemicellulose prepared in Example 4 has a degree of substitution of 0.163, which lowers the surface energy while retaining the hydroxyl groups on the hemicellulose to form hydrogen bonds with the paper, making the superhydrophobic surface more durable.

[0055] Comparative Example 1

[0056] (1) 5 g (7.5 mmol dehydrated xylose units) of hemicellulose obtained by alkali extraction was taken and stirred continuously at 60 ° C in a heated magnetic stirrer to completely dissolve it in 60 ml DMSO; when the temperature dropped to 50 ° C, 0.5 g 4-dimethylaminopyridine (DMAP) and hexadecenylsuccinic anhydride (HDSA, 322.48 g / mol) were added to the system to obtain a mixed solution (HDSA was pre-dissolved in 10 ml DMSO and slowly added to the system within ten minutes), and the molar ratio of hemicellulose to hexadecenylsuccinic anhydride was 1:0.3; the mixed solution was reacted at 50 ° C for 6 h with a stirring speed of 500 rpm; after the reaction, the above reaction solution was added into four times its volume of continuously stirred anhydrous ethanol, the stirring was stopped and the solution was allowed to stand overnight, washed and centrifuged, and dried to obtain a long-chain anhydride-modified hemicellulose sample.

[0057] (2) Long-chain anhydride-modified hemicellulose was dissolved in 20 mL of deionized water, and nanosilica was dispersed in a mass ratio of long-chain anhydride-modified hemicellulose to nanosilica of 1:1 to obtain a hemicellulose-nanosilica dispersion; a 12 cm × 10 cm filter paper was immersed in the hemicellulose-nanosilica dispersion, and then placed in a 105 ° C oven for short drying, and the immersion-drying was repeated three times. After completion, it was placed in a 105 ° C oven for drying and then placed in a constant temperature and humidity chamber to maintain 25 ° C and 50% humidity, and the coated filter paper was flattened with a weight to obtain a long-chain anhydride-modified hemicellulose hydrophobic filter paper, which was recorded as D1.

[0058] The initial contact angle of sample D1 in comparative example 1 was only 101.56°, which dropped to 50.68° after 14 seconds, failing to achieve superhydrophobicity. In addition, the stability was poor, and the number of abrasion resistance was 20 to 40 times. SEM and EDS images showed that nano-silica agglomerated on the paper surface, and the adsorption amount was small.

[0059] Comparative Example 2

[0060] (1) 5 g (7.5 mmol dehydrated xylose units) of hemicellulose obtained by DMSO extraction was taken and continuously stirred at 60°C in a heated magnetic stirrer to completely dissolve it in a 2 wt% lithium chloride / N,N-dimethylformamide solution. The solid-liquid ratio of hemicellulose to lithium chloride / N,N-dimethylformamide solution was 1 g:20 mL. N-bromosuccinimide (NBS) was used as a catalyst, acetic anhydride was added (the molar ratio of hemicellulose to acetic anhydride was 5:1) and stirred at 50°C and 200 rpm for 2 h. After the reaction was completed, the reaction solution was cooled to room temperature. After the reaction was completed, the reaction solution was added into four times its volume of continuously stirred anhydrous ethanol, the stirring was stopped and the solution was allowed to stand overnight. After washing, the solution was centrifuged and dried to obtain an acetylated hemicellulose sample.

[0061] (2) Acetylated modified hemicellulose was dissolved in 20 mL of deionized water, and nanosilica was dispersed in a mass ratio of acetylated modified hemicellulose to nanosilica of 1:1 to obtain a hemicellulose-nanosilica dispersion; a 12 cm × 10 cm filter paper was immersed in the hemicellulose-nanosilica dispersion, and then placed in a 105 ° C oven for short drying, and the immersion-drying was repeated three times. After completion, it was placed in a 105 ° C oven for drying and then placed in a constant temperature and humidity chamber to maintain 25 ° C and 50% humidity, and the coated filter paper was flattened with a weight to obtain a filter paper coated with acetylated modified hemicellulose, which was recorded as D2.

[0062] The initial contact angle of sample D2 in comparative example 2 was only 75.69°, which dropped to 25.32° after 14 seconds, failing to achieve super hydrophobicity. The stability was poor, and the number of abrasion resistance was 10 to 20 times. Compared with example 2, the hydrophobicity decreased significantly.

[0063] Comparative Example 3

[0064] (1) 5 g (7.5 mmol of dehydrated xylose units) of hemicellulose obtained by alkali extraction was taken and stirred continuously at 60°C in a heated magnetic stirrer to completely dissolve it in 60 ml of alkaline aqueous solution (sodium hydroxide was used as a catalyst), and a certain amount of bromododecane (the molar ratio of hemicellulose to bromododecane was 1:0.5) was added to obtain a mixed solution; the mixed solution was reacted at 50°C for 5 h with a stirring speed of 500 rpm; after the reaction, the above reaction solution was added into four times its volume of continuously stirred anhydrous ethanol, the stirring was stopped and the solution was allowed to stand overnight, washed, centrifuged, and dried to obtain a halogenated hemicellulose sample.

[0065] (2) The hemicellulose obtained after the etherification reaction of the halogenated substance was dissolved in 20 mL of deionized water, and nanosilica was dispersed in a mass ratio of 1:1 between the halogenated hemicellulose and nanosilica to obtain a hemicellulose-nanosilica dispersion. A 12 cm × 10 cm filter paper was immersed in the hemicellulose-nanosilica dispersion and then placed in a 105 ° C oven for short drying. The immersion-drying was repeated three times. After completion, it was dried at 105 ° C and placed in a constant temperature and humidity chamber to maintain 25 ° C and 50% humidity. The coated filter paper was flattened with a weight to obtain a sample denoted as D3.

[0066] The initial contact angle of sample D3 in comparative example 3 was only 98.35°, which dropped to 48.32° after 14 seconds, failing to achieve super hydrophobicity. The stability was also poor, with a wear resistance of 10 to 20 times. Compared with example 3, its hydrophobicity and stability were poor.

[0067] Comparative Example 4

[0068] (1) 5 g (7.5 mmol of dehydrated xylose units) of hemicellulose extracted with DMSO was completely dissolved in 250 mL of acetate buffer (0.1 mol / L, pH = 4.5) by continuous stirring at 60°C in a heated magnetic stirrer and stirred for 30 min. Dodecylamine (dissolved in anhydrous ethanol) and catalyst 2-methylpyridine borane were then added, wherein the molar ratio of hemicellulose to dodecylamine was 1:0.2. The reaction was carried out at 50°C for 12 h. After the reaction was completed, the reaction solution was added to four times its volume of continuously stirred anhydrous ethanol, and the stirring was stopped and the solution was allowed to stand overnight. After washing, the solution was centrifuged and dried to obtain a reductively aminated hemicellulose sample.

[0069] (2) The hemicellulose obtained after reductive amination modification was dissolved in 20 mL of deionized water, and nanosilica was dispersed in a mass ratio of 1:1 between the reductive amination modified hemicellulose and nanosilica to obtain a hemicellulose-nanosilica dispersion; a 12 cm × 10 cm filter paper was immersed in the hemicellulose-nanosilica dispersion, and then placed in a 105 ° C oven for short drying, and the immersion-drying was repeated three times. After completion, it was placed in a 105 ° C oven for drying and then placed in a constant temperature and humidity chamber to maintain 25 ° C and 50% humidity, and the coated filter paper was flattened with a weight to obtain a sample recorded as D4.

[0070] The initial contact angle of sample D4 in Comparative Example 4 was only 87.21°, which dropped to 38.14° after 14 seconds, failing to achieve super-hydrophobicity. Furthermore, the stability was poor, with a wear resistance of 10 to 30 times. Compared with Example 4, its hydrophobicity and stability were significantly insufficient.

[0071] Figure 1 Figures a and b show SEM images of filter paper without hemicellulose and nanosilica loading, H1, H2, H3, H4, and Comparative Example 1, respectively. Clear fiber lines can be seen on the initial filter paper. Figure b shows Comparative Example 1, where unevenly dispersed nanosilica particles can be seen. This indicates that using low-surface-energy hemicellulose as a dispersant to disperse nanoparticles causes both nanosilica and hemicellulose to deposit simultaneously on the paper surface, resulting in agglomeration of the silica nanoparticles and a decrease in the adsorption of hemicellulose to paper. Figures c, d, e, and f show Examples 1-4, respectively. A relatively uniform dispersion and the formation of layered nanosilica can be observed, demonstrating that silica can be more evenly deposited on low-surface-energy hemicellulose, forming a rough surface structure. Furthermore, the adsorption properties and affinity of the hemicellulose modified with low-surface-energy substances for paper are not reduced by the introduction of the low-surface-energy substances.

[0072] Figure 2 The EDS images of Examples 1-4 and Comparative Example 1 show that the low-surface-energy hemicellulose used as a dispersant adsorbs significantly less nano-silica, while Examples 1-4 adsorb a larger amount of nano-silica, and the distribution is more uniform. Figure e is Comparative Example 1.

[0073] Figure 3 It is a line graph of the water contact angle of Comparative Examples 1-4 and Examples 1-4. Figure 4The water contact angle images of Examples 1-4 are shown. The hemicellulose modified with low surface energy substances in Examples 1-4 not only reduces the surface energy on the paper surface, but also adsorbs nano-silica and drives the self-assembly of nano-silica to form a rough nano-hydrophobic structure on the surface. The maximum contact angle reaches 157.05°. In addition to having a good hydrophobic effect, the natural affinity of hemicellulose with paper also makes it have good stability. Hemicellulose modified with low surface energy substances is used as an adsorbent for constructing super-hydrophobic surfaces. It not only does not affect the environment and is easy to recycle paper, but also reduces the surface energy of paper while uniformly adsorbing nanoparticles, saving costs.

[0074] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A method for constructing a super-hydrophobic surface of paper using hemicellulose as a nanoparticle adsorbent, characterized in that: The following steps are involved: (1) Hemicellulose extracted from plant fiber raw materials is added to a solvent system, and a chemical derivatization agent and a catalyst are added to chemically modify the hemicellulose to obtain chemically derivatized hemicellulose; the catalyst is at least one of 4-dimethylaminopyridine, p-toluenesulfonic acid, dimethylaniline, anhydrous sodium acetate and N-bromosuccinimide, sodium hydroxide, potassium hydroxide, and 2-methylpyridine borane; the chemical derivatization agent is at least one of octylsuccinic anhydride, dodecenylsuccinic acid, hexadecenylsuccinic anhydride, acetic anhydride, propionic anhydride, nitroanhydride, valeric anhydride, dodecane bromide, cyclohexane bromide, p-carboxymethylbenzene bromide, benzyl bromide, dodecylamine, hexadecylamine, and octylamine; The molar ratio of the chemical derivatization agent to hemicellulose is 1:10 to 2:1; (2) loading the chemically derivatized hemicellulose prepared in step (1) onto paper fibers; (3) The nanoparticles are dispersed in a solvent to obtain a nanoparticle dispersion, and the paper fibers treated in step (2) are immersed in the nanoparticle dispersion so that the nanoparticles are adsorbed by the chemically derivatized hemicellulose and deposited on the paper fibers to construct a superhydrophobic surface.

2. The method according to claim 1, characterized in that The plant fiber raw material in step (1) is at least one of corn stalks, bagasse, hardwood, corn cobs and oil tea husks.

3. The method according to claim 1, characterized in that The molar ratio of the chemical derivatization reagent to hemicellulose in step (1) is (2-5):

10.

4. The method according to claim 1, wherein The reaction temperature for chemically modifying hemicellulose in step (1) is 20°C to 90°C, and the reaction time is 4 to 24 h.

5. The method according to claim 1, wherein The solvent system described in step (1) is at least one of dimethyl sulfoxide, tetrahydrofuran, water, dimethylamide / lithium chloride system, acetate buffer, ionic liquid, and acetone.

6. The method according to claim 1, characterized in that The solid-liquid ratio of the hemicellulose and solvent system described in step (1) is 1 g:10 mL to 1 g:100 mL.

7. The method according to claim 6, characterized in that The solid-to-liquid ratio of the hemicellulose and solvent system described in step (1) is 1 g:30 mL to 1 g:50 mL.

8. The method according to claim 1, characterized in that The degree of substitution of the chemically derivatized hemicellulose obtained by the modification in step (1) is 0.1-0.

5.

9. The method according to claim 1, characterized in that The chemically derivatized hemicellulose described in step (2) is first dispersed into a dispersion system and then loaded onto paper fibers; the dispersion system is at least one of water, ethanol, chloroform, water / ethanol, and chloroform / ethanol systems.

10. The method according to claim 1, characterized in that The method for loading the chemically derivatized hemicellulose onto the paper fibers in step (2) is at least one of coating and impregnation.

11. The method according to claim 1, wherein The method for loading the chemically derivatized hemicellulose onto the paper fibers in step (2) is chemical vapor deposition.

12. The method according to claim 1, characterized in that The method for loading the chemically derivatized hemicellulose onto paper fibers described in step (2) is a wet chemical method.

13. The method according to claim 1, wherein The nanoparticles described in step (3) are at least one of nanometal particles and nanosilicon particles.

14. The method according to claim 1, wherein The nanoparticles described in step (3) are at least one of nano-silicon dioxide particles, carbon nanotube particles, zinc oxide particles, and nano-titanium dioxide.

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