Method for preparing surface-functionalized cellulose nanospheres

Abstract

The present invention relates to a method for preparing surface-functionalized cellulose nanospheres, which comprises (1) adding cellulosic fibers to the alkali liquor, swelling, filtering the solution, washing the product with water for several times until pH is 7, and drying to constant weight; (2) then adding the above product into mixed acid for fully infiltrating, reacting the above solution under stirring for 2-10 hours at 60-90 DEG C, naturally cooling the reaction products, adding an alkali solution until the pH of the solution is adjusted to 7 to obtain a dispersion liquid of cellulose nanospheres, then centrifuging the dispersion liquid, washing with water for three times, carrying out ultrasonic treatment, and then carrying out freeze drying to constant weight to obtain a cellulose nanospheres. The preparation method has advantages of low raw material cost, simple preparation process and mild preparation conditions; the surfaces of the cellulose nanospheres have functional groups, so that thermal stability and hydrophobicity are improved, self-aggregation is reduced, dispersion is easy, size is small, distribution is narrow, control is easy, specific surface area is large, reactivity is high and etc.

Description

technical field [0001] The invention belongs to the field of preparation of cellulose nanocrystals, in particular to a preparation method of surface functionalized cellulose nanospheres. Background technique [0002] Due to the high aspect ratio, excellent mechanical properties, fully degradable and renewable properties of cellulose nanowhiskers or nanocrystals, their use has been proposed as a main component for the development of new inexpensive biomaterials (Sturcova A, Davies GR , Eichhorn SJ. Elastic modulus and stress-transfer properties of tunicate cellulose whiskers. Biomacromolecules 2005; 6: 1055-1061.). Cellulose nanocrystals have some additional advantages for biopolymers due to their non-abrasive processability, allowing high filler content and significant cost savings, including their extensive resources, if compared to other inorganic reinforcing fillers Availability, low energy consumption, easy recycling including combustion, high sound attenuation and fair...

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Problems solved by technology

[0003] The current preparation method of cellulose nanospheres was first reported by Cheng's research group (Wang N, Ding EY, Cheng RS. Preparation and liquid crystalline properties of spherical cellulose nanoparticles. Langmuir 2008;24:5-8.), they used The cellulose nanospheres are obtained by treating microcrystalline cellulose with a mixed acid of inorganic strong acid, centrifuging for many times, dialysis, and vacuum drying; the disadvantage is that the preparation process is complicated and the post-treatment is cumbersome

Later, researchers used enzymatic hydrolysis, sulfuric acid method and sulfuric acid mixed acid method to prepare cellulose nanospheres, but these methods have some problems, such as long reaction time of enzymatic hydrolysis, low yield, complicated reaction equipment, etc. (Satyamurthy P , Vigneshwaran N, A novel process for synthesis of spherical nanocellulose by controlled hydrolysis of microcrystalline cellulose using anaerobic microbial consortium. Enzyme and Microbial Technology 2013; 52: 20-25)

However, the size of the cellulose nanospheres obtained by adding sulfuric acid acid hydrolysis is not uniform enough, and the surface has sulfate groups, resulting in a reduction in its thermal stability (Xiong R, Zhang XX, Tian D, Zhou ZH, Lu CH.Comparing microcrystalline with spherical nanocrystalline cellulose from waste cotton fabrics. Cellulose 2012; 19:1189-1198 Wang N, Ding EY, Cheng RS. Thermal degradation behaviors of spherical cellulose nanocrystals with sulfate groups. Polymer 2007; 48: 49386)6

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