Synthesis And Properties Of Acylated Modified Chitosan And Chitooligosaccharides

Acylation on chitosan and chitooligosaccharides can weaken the Intermolecular and intramolecular hydrogen bond by reducing the number of amino or hydroxyl. Then the the solubilities of chitosan and chitooligosaccharides in organic solvents can be improved. As a result, Acylation on chitosan and chitooligosaccharides can provide more reaction environment for further modifying. The chain structure and the liquid crystal properties of acylate derivant changed. And the biological properties might be improved. The research might lead a new way for designing sugar derivatives applying on biology, medicine and other fields.Four thermotropic liquid crystal monomers were synthesized. They are5-(4-allyloxybenzoyloxy)-4’-hydroxybiphenyl-4"-biphenylol hexanedioic acid,9-(4-allyloxyybenzoyloxy)-4’-hydroxybiphenyl-4"-biphenylol pelargonic acid,5-(4-ethoxy benzoyloxy)-4’-hydroxybiphenyl-4"-biphenylol hexanedioic acid,9-(4-ethoxyben zoyloxy)-4’-hydroxybiphenyl-4"-biphenylol pelargonic acid. Chitosan and chitoolig-osaccharides derivant with different length spacer were synthesized by connecting these four monomers and Chenodeoxycholic Acid as well as Dodecanoic Acid with side chain of chitosan and chitooligosaccharides. These derivant were set as series of Pi and series of P2. The chemical structures and properties of these compounds were confirmed by FT-IR spectroscopy, visible absorption spectrum (UV), thermogravi-metric analyses (TGA), differential scanning calorimetry (DSC) and polarizing optical microscopy (POM),The result of FT-IR spectroscopy, visible absorption spectrum and the physical and chemical properties of the product proved that the monomer and polymer molecular were synthesized successfully. The result of thermal analysis showed that the thermal stability significantly decreased with the introduction of the new long axis. The result of polarization analysis showed that the critical concentration increased when chitosan was acylated. And the longer flexible chain was, the higher was the critical concentration of the graft product. The color of the texture was more vivid as the decreasing of the axis ratio of the graft chain. In other words, the introduction of group with short axis ratio helps the formation of lyotropic liquid crystal. Chitooligosaccharides and its derivant had poor liquid crystal textures. And the liquid crystal range was narrow. When the concentration reached a certain degree, the derivant was rapidly crystallization. The derivant were easily form fiber shape, and distributed loosely in solution. As a result, they can easily form thin crystal. Forthermore, The derivant of chitooligosaccharides has good moisture retention.