Preparation And Property Study Of Nanocrystalline Cellulose Cholesteric Liquid Crystal

Cellulose is the most abundant natural polymer in the world. It is the main structural constituent of wood and higher plants. Many products are derived from cellulose, including cellulose nanocrystals or nanocrystalline cellulose (NCC), also called whiskers. Cellulose nanocrystals are often referred to as microcrystals, whiskers, nanocrystals, nanoparticles, microcrystallites, or nanofibers. This nanomaterial has received a great deal of attention in the last two decades, particularly for its potential applications as reinforcement or nanofillers in polymer composites and its unique self-assembly and optical properties.The main content of this study is:The uniform size, good dispersion of cellulose nanocrystals suspension was prepared by sulfuric acid hydrolysis of filter cotton cellulose; The results showed that:the best reaction condition of the preparation of nanocrystalline celluloseas follows:the sulfuric acid concentration was64%, the reaction temperature was45℃, reactiontime were2h.The use of sulfuric acid to produce NCC imparts sulfate ester groups to the cellulose nanocrystal surfaces, showing limited dispersibility. Aqueous NCC suspensions can be evaporated to produce solid semitranslucent NCC films that retain the self-assembled chiral nematic liquid crystalline order formed in the suspension. These films are iridescent and reflect left-handed circularly polarized light in a narrow wavelength band. Therefore, in this paper, the condition of preparing cellulose nanocrystals membrane material has carried on the exploration, and for various performance characterizations. The results showed that the optimum temperature of film forming is30℃and the thickness of the film is about100μm. The film using a suspension at the optimal preparation conditions, which is obtained by the above method preparation of cellulose nanocrystals membrane materials can observe the cholesteric liquid crystal phase and complete phase structure of fingerprint.The properties of nanocrystalline cellulose suspension with applying ultrasonic energy were then characterized. The structure and optical properties of the cellulosic nanocrystal films were studied. We tried to provide more details about how the applying ultrasonic affect the cellulose microstructure and properties of the ordered nanocrystalline phase. The method for developing NCC film iridescence color can precisely tailor the desired properties without the need for additives. Sonication treatment was used to fabricate more uniform cellulose nanoparticles. The properties of cellulose nanocrystalline suspension with applying ultrasonic energy were then characterized by photon correlation spectroscopy and transmission electron microscope. The structure and optical properties of the cellulosic cellulose nanocrystal films were characterized by polarized optical microscope and UV-3600spectrophotometer. It was found that with the applying of sonication, the pitch and wavelength of the CNC solid film increase. And it is a linear relationship between pitch and wavelength. Also, in-depth studies of the microstructure of CNC solid films by a relatively high sonication power, revealed focal conic defects.