Study on the dispersibility of nano-chitin and its enhancement performance on regenerated cellulose films
Nano-chitin is a nanoscale material derived from natural polysaccharide chitin,and has various excellent properties such as biocompatibility,biodegradability and high specific surface area.This makes it have broad application potential in various fields such as biomedicine,food,cosmetics,environmental protection,textiles and packaging.However,one of major challenges for the nano-chitin is its poor dispersibility.Due to the high specific surface area and surface activity of nanoparticles,they are prone to agglomerate in solution and form larger aggregates,which limits their uniform distribution in composite materials and hinders their reinforcement effect.The aggregation of nano-chitin can lead to the deterioration in composite materials properties,such as mechanical strength,optical properties and antibacterial effects.To improve the dispersibility of nano-chitin,the following strategies are usually adopted:increasing surface charge or introducing hydrophilic groups through chemical modification can enhance the stability of nanoparticles in aqueous media;adding appropriate dispersants or surfactants can help stabilize nanoparticles and prevent aggregation;utilizing the cavitation effect of ultrasound can disrupt the attraction between particles and promote the uniform dispersion of nano-chitin in solution.Almong these strategies,using dispersants to disperse nano-chitin is relatively simpl and efficient.Therefore,a suitable dispersant DMSO(dimethyl sulfoxide)was selected in this article for uniform dispersion of nano-chitin,and then the enhancement effect of nano-chitin on regenerated cellulose films was further studied.To improve the dispersion effect of nano-chitin,firstly a series of techniques such as transmittance,turbidity testing and centrifugal sedimentation experiments were adopted to investigate the dispersibility of nano-chitin in water(H2O),tetraethylammonium hydroxide aqueous solution(TEAOH/H2O),urea aqueous solution of different mass fractions(Urea/H2O),and dimethyl sulfoxide(DMSO).It was found that DMSO had a relatively good ability to disperse nano-chitin.The initial transmittance of 0.5％nano-chitin/DMSO suspension at 800 nm could reach 91.9％and it still maintained 86.2％after 72 hours.The turbidity remained at the level of 52.5-69.0 NTU and there was no obvious precipitation after high-speed centrifugation.Therefore,DMSO was selected as the nano-chitin dispersant and different mass fractions of nano-chitin/DMSO were added to cellulose/TEAOH/H2 O solution to prepare regenerated cellulose composite films.The structure,morphology and mechanical properties of the composite films were characterized.The results showed that the mechanical properties of the composite films were optimal and the fracture strength and elongation at break increased by 54％and 150％compared to the pure cellulose films,when the amount of nano-chitin added was 9％.The addition of 9％nano-chitin helped to introduce amide groups and improveed crystallinity in the composite films.The surface and cross-sectional structure of the composite films were dense and homogenous without obvious lamination and pores,and nano-chitin was generally evenly dispersed in the composite film without obvious aggregation.This study improves the dispersion and aggregation problems of nano-chitin in the preparation of regenerated cellulose films and significantly enhances the comprehensive performance of regenerated cellulose composite films by using DMSO as a dispersion medium.This study helpes to expand the application fields of nano-chitin in high value-added materials and has important theoretical value and application prospects.Future research will further explore the effects of different additives on the dispersion of nano-chitin and the properties of composite materials with the aim of developing regenerated cellulose composite materials with better performance.
nano-chitindimethyl sulfoxidedispersibilitytetraethyl ammonium hydroxideregenerated cellulose composite films
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