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High-carboxyl-substituted hairy cellulose nanocrystal and preparation method thereof

A technology of carboxylated cellulose and nanocrystals, applied in the direction of nanotechnology, nanotechnology, nanotechnology, etc. for materials and surface science, can solve the problem of affecting the stability of the product nanocellulose crystal, affecting the purity of the final product NCC, cellulose Problems such as the loss of amorphous areas, to achieve the effect of high amorphous cellulose content, increase product charge content, and low equipment requirements

Pending Publication Date: 2021-12-07
SOUTH CHINA UNIV OF TECH
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Problems solved by technology

Chinese patent CN108219008A discloses a nano-cellulose crystal and method prepared by acid hydrolysis of cellulose microfibrils. The invention disassembles cellulose through homogeneous treatment, which can improve the efficiency of subsequent NCC preparation. Amorphous regions in the cellulose structure, while retaining the crystalline regions of cellulose that are stable under hot acid conditions, which leads to the loss of a large amount of amorphous regions in the cellulose, resulting in low product yields
Chinese patent CN105603020A discloses a method for preparing nano-cellulose crystals. The NCC prepared by this method has a high yield, but the surface of the obtained NCC has no charge, and the dispersion stability of the solution is poor, which is not conducive to subsequent applications.
Based on the problems of the above NCC preparation technology in terms of yield and product stability, Chinese patent CN108484782A discloses a carboxylated modified nano-cellulose crystal and a preparation method thereof. The method uses microcrystalline cellulose as a raw material, utilizes TEMPO, A composite oxidant composed of sodium periodate, sodium hypochlorite and sodium chlorite is used to oxidize microcrystalline cellulose in a "one-pot method" to obtain carboxylated modified cellulose, which is then treated with a micro-jet high-pressure homogenizer to obtain carboxylated modified cellulose. NCC, the method uses microcrystalline cellulose as raw material, due to the compact structure of microcrystalline cellulose and the strong hydrogen bond interaction in the molecule, the carboxylation modification only occurs on the surface of microcrystalline cellulose, resulting in the degree of carboxylation of the product is not high, thus affecting the stability of the product nanocellulose crystals in solution; at the same time, the "one-pot method" of multiple oxidants used in this method is simultaneously oxidized, and there is competition for active hydroxyl groups among several oxidants, which will lead to oxidation The efficiency is much lower, and at the same time, it also restricts the selectivity of various oxidants to oxidation sites, so the degree of carboxylation of the product is lower; in addition, the "one-pot" oxidation leads to a complex composition of the product, which affects the final product NCC the purity of

Method used

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  • High-carboxyl-substituted hairy cellulose nanocrystal and preparation method thereof
  • High-carboxyl-substituted hairy cellulose nanocrystal and preparation method thereof
  • High-carboxyl-substituted hairy cellulose nanocrystal and preparation method thereof

Examples

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Embodiment 1

[0049] Using sisal slag fiber as raw material, each gram of absolute dry fiber was dissolved in 100mL of phosphate buffer (0.05mol / L, pH=7) to form a slurry with a concentration of 1% (w / v), and added TEMPO0.016g, 10mmol NaClO 2 and 1mmol NaClO; at 60°C, 500rpm magnetic stirring for 6h after the reaction, the pH remained unchanged, and 100mL of absolute ethanol was added to terminate the reaction, and the obtained oxidized sample was repeatedly washed until the pH of the solution was neutral, and the precipitated slurry was collected by filtration. The oxidized cellulose was added into deionized water to form a 0.5% (w / v) suspension, treated with 800W ultrasonic for 30 minutes, then vacuum-filtered and washed until the pH value was neutral. Add 150mL of acetic acid-sodium acetate buffer solution with a pH of 4.5 to every gram of C6-carboxyl nanocellulose, add 3g of sodium periodate to every gram of C6-carboxyl nanocellulose, and avoid stirring at 30°C and 200rpm After 6 hours...

Embodiment 2

[0052] Using eucalyptus fiber as raw material, each gram of dry fiber was dissolved in 100mL of phosphate buffer (0.05mol / L, pH=7) to form a slurry with a concentration of 1% (w / v), and TEMPO was added to it 0.016g, 9mmol NaClO 2 and 2mmol NaClO; at 55°C, under 500rpm magnetic stirring for 6h, the pH remained unchanged, and 100mL of absolute ethanol was added to terminate the reaction, and the obtained oxidized sample was repeatedly washed until the pH of the solution was neutral, and the precipitated slurry was collected by filtration. The oxidized cellulose was added into deionized water to form a 0.8% (w / v) suspension, treated with 1000W ultrasonic for 30 minutes, then vacuum-filtered and washed until the pH value was neutral. Add 150mL of acetic acid-sodium acetate buffer solution with a pH of 4.5 to every gram of C6-carboxyl nanocellulose, add 3g of sodium periodate to every gram of C6-carboxyl nanocellulose, and avoid stirring at 30°C and 200rpm After 8 hours of photore...

Embodiment 3

[0055] Using bamboo fiber as raw material, each gram of dry fiber is dissolved in 100mL of phosphate buffer (0.05mol / L, pH=7) to form a slurry with a concentration of 1% (w / v), and TEMPO 0.018 g, 9 mmol NaClO 2and 3mmol NaClO; at 55°C, under 450rpm magnetic stirring for 7h, the pH remained unchanged, and 100mL of absolute ethanol was added to terminate the reaction, and the obtained oxidized sample was repeatedly washed until the pH of the solution was neutral, and the precipitated slurry was collected by filtration. The oxidized cellulose was added into deionized water to form a 0.6% (w / v) suspension, treated with 900W ultrasonic for 40 minutes, then vacuum-filtered and washed until the pH value was neutral. Add 200mL of acetic acid-sodium acetate buffer solution with a pH of 4.5 to every gram of C6-carboxyl nanocellulose, add 5g of sodium periodate to every gram of C6-carboxyl nanocellulose, and avoid stirring at 35°C and 198rpm. After 5 h of photoreaction, 5 mL of ethylene...

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Abstract

The invention relates to the field of biopolymer materials, and particularly discloses a highly substituted carboxyl cellulose nanocrystal and a preparation method thereof. The preparation method comprises the steps: dispersing plant cellulose in deionized water, firstly oxidizing by using a TEMPO / NaClO / NaClO2 oxidation system, then carrying out ultrasonic treatment, adding periodate for oxidation, adding a sodium chloride-sodium chlorite-hydrogen peroxide multi-element oxidant, carrying out stirring reaction at room temperature, and finally carrying out heating treatment to obtain a final product. According to the method, carboxyl substitution is controlled in an amorphous region of cellulose by adopting a step-by-step oxidation method, so that the carboxylation substitution degree is improved, and then chain scission is performed on the carboxylated cellulose in the amorphous region through thermal degradation, so that the hairy cellulose nanocrystal with amorphous carboxylated cellulose at two ends is formed. The surface carboxyl content, the carboxyl substitution degree and the like of the nanocellulose crystal are remarkably improved, the operation process is simple and convenient, pollution is avoided, and large-scale popularization and production can be achieved.

Description

technical field [0001] The invention relates to the field of biopolymer materials, in particular to a hair-like cellulose nanocrystal substituted with a high carboxyl group and a preparation method thereof. Background technique [0002] There are two nanoscale cellulose units distributed in the molecular structure of cellulose: cellulose crystals and amorphous cellulose, which rely on their intramolecular and intermolecular hydrogen bonds and weak van der Waals forces to maintain the self-assembled macromolecular structure and original structure. Fiber shape. Nanoscale crystalline cellulose can be obtained by removing amorphous cellulose by a special process, usually called nanocellulose crystals (NanoCellulose Crystals, NCC) (or cellulose nanocrystals, CNC), which is a cellulose-based Ultrafine fiber nanomaterials with a diameter of less than 100nm not only have the non-toxic, renewable and degradable properties of natural cellulose, but also have typical characteristics o...

Claims

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Application Information

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IPC IPC(8): C08B15/04B82Y40/00B82Y30/00
CPCC08B15/04B82Y40/00B82Y30/00
Inventor 王兆梅朱维金冬冬季杏迪
Owner SOUTH CHINA UNIV OF TECH
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