Study On Preparation And Processing Method Of Chitosan Based Liquid Crystal Materials

Liquid crystal materials is a hot topic of research and development in high-tech fields.Chitosan is expected to become a new kind of natural polymer liquid crystal materials. As anew member in the natural polymer liquid crystal materials, the application research ofchitosan has a attractive prospect. As a functional and ecological friendly fiber, chitosan fibersare used in biomedical and biotechnology fields. In recent years, most countries aredeveloping chitosan fibers as functional health fibers, its market has a good prospect. Themodification of chitosan and preparation of chitosan fibers with a high strength can promotethe chitosan development and broaden its application field. Ionic liquid is a new kind ofenvironment friendly solvent, it arouses scientists’ wide attention all over the world. Thepreparation of ionic liquid which can dissolve chitosan and react in homogeneous reactionsystem has become a urgent problem to be solved.Starting from the chitosan materials and arounding the ionic liquid, this paper mainlycarries out two aspects of research works in order to prepare the chitosan based liquid crystalmaterials.1.Glycine hydrochloride ionic liquid was synthesized using glycine and36%hydrochloric acid by mass fraction as raw materials. A high-deacetylation degree chitosanwith the deacetylation degree up to92.2%was prepared from chitosan raw material byintermittent alkali treatment. N-benzyl chitosan was produced from benzaldehyde andhigh-deacetylation degree chitosan in presence of acetic acid or glycine hydrochloride ionicliquid by N-alkylation chemical modification. The infrared spectrometry results showed thatN-benzyl chitosan was the products prepared by these two methods. Glycine hydrochlorideionic liquid was proved to be a good solvent for chitosan. The critical mass fraction for liquidcrystal phase was measured as9%by polarizing microscopy. The liquid crystal wascholesteric phase.2. The high deacetylation degree chitosan was prepared by treating chitosan raw materialin the intermission alkali treatment. High deacetylation degree chitosan was dissolved in the [Gly]Cl aqueous solution and spun it into fiber via wet spinning process. The obtained fiberwas surface crosslinked in some degree to produce a chitosan fiber with fairly goodmechanical properities. It proves that the chitosan fiber has good surface morphology andthermal stability. The results showed that the fiber can be produced with breaking strength0.307CN/dtex and elongation35.933%under the condition as followed:6.5%chitosan bymass fraction based on3%ionic liquid [Gly]Cl aqueous solution, dissolution temperature40℃, dissolution time6h, volume ratio in coagulating bath of anhydrous alcohol and5%sodium sulfate aqueous solution50/50. The breaking strength of fiber was up to1.977CN/dtex after surface crosslinking.