Preparation And Rheological Study Of Organic Boron-zirconium-Crosslinked Polysaccharide Gels

Konjac glucomannan （Abbr. KGM） and Chitosan (Abbr. CTS), naturalpolysaccharide, have favorable biodegradability, biocompatibility, water-preserving,filming abilities, and thickening. The recent studies on the foundation andapplications of KGM and CTS in foods, bio-technical, petroleum chemical and somenew materials fields came to front. The main contents and conclusions were asfollows:1、Organic boron-zirconium and KGM as raw materials were adopted to prepareKGM/organic boron-zirconium complex gel. The mechanism was below. The freeboron acid radical ion of organic boron-zirconium has the ability to crosslink withcis-diol vicinal hydroxyl group in in the mannose units of the KGM molecular chains.Borate ions need to get rid of Zr-based composite organic ligands bound to make thecrosslinking reaction with cis-diol vicinal hydroxyl group occurs, so the dynamicscharacteristics in the gel-crosslinking processes was put up the feature of retardingcrosslinking activity. Dynamic viscosity behavior was studied with the rheologicalspectrometer. The results showed that the critical sol-gel transition points and thegelation time can be exactly determined by the Winter-Chambon criterion. The effectof temperature, concentration of KGM and organic boron-zirconium on the criticalgelation points and the elasticity of the gels were discussed.2、Organic boron-zirconium and CTS as raw materials was adopted to prepareCTS/organic boron-zirconium complex gel. The preparing mechanism was below.The gel network was formed through the crosslinking reaction between borate ionsdissociated from organic boron-zirconium and the cis-diol hydroxyl groups on theCTS molecular chain. Borate ions have to escape from the binding of coordinationagent and then can crosslink with the cis-diol hydroxyl groups, so the system of CTS/organic boron-zirconium complex gel reflected the dynamic characters and crosslinkdelayed. In addition, the impact of changes in concentration of CTS and organiczirconium on complex gel system with the storage modulus, loss modulus and sol-geltransition point was also been analyzed. The rheological experiments and analysiswith changes of temperature conditions showed that the critical sol-gel transition points and the gelation time can also be exactly determined by the Winter-Chamboncriterion. The effect of temperature, concentration of CTS and organicboron-zirconium on the critical gelation points and the elasticity of the gel werediscussed.The results of this research provided essential scientific datas and theoreticalfoundation for the further development and application of biomacromolecule-basedgels. Therefore, this study has theoretical significance and applied prospect, which iswell consistent with the targe of environmental protection and the strategy ofsustainable development.