Synthesis And Characterization Of Chitosan-g-Poly (D, L-Lactic Acid)

The family of poly (D, L-lactic acid)s and their copolymers has attached much attention in medical and pharmaceutical applications owing to their biodegradability and bioenvironmental compatibility. However, their clinical applications are sometimes interfered with the high hydrophobic and consequent poor water holding-up, which in turn resulting in a slow hydrolytic degradation arte. Another potential disadvantage is the complications resulting from the accumulation of lactic acid produced in the process of PLAs degradation.Chitosan (CS) and its modified analogs have been widely used in medicine, cosmetics, agriculture and biotechnology. But chitosan is not soluble in any organic solvent and it is only soluble in aqueous solutions of some acids owing to the rigid crystalline structures formation because of the intramolecular and intermolecular hydrogen bonding, thus its applications are limited and it is difficult to process. If we can prepare the copolymer of CS and PLA, the crystability and acidic enviroment produced during the degradation of PLA will be improved.In our article, we prepared the PDLA of lower molecular weight (OPLA-OH) through direct polycondensation in the first time. Afterward, we gained OPLA-NCO through the reaction of OPLA-OH and TDI.And on the base of overall work; we gained a serious of grafting copolymers of PDLA and CS (PLCS) with different molecular weight CS in homogeneous or heterogeneous media. Moreover, we gained the second graft polymerization through the reaction of OPLA-NCO and the PLCS.The technology of the graft polymerization is detailedly studied.We analysized the structure of the grafting copolymer by IR, 1H-NMR,DSC,X-ray and TG. Moreover the hydrophility thermal performance, crystabilty performance, hydrophility and swelling degree of the graftiong copolymers were studied in details.Furthermore, the copolymer of the phthaloyl and CS (PHCS) were prepared. And then the copolymers of PHCS and PDLA were prepared through ring-opening polymerization of lactide and the graft polymerization of OPLA-NCO respectively. The preliminary characterizations of the graft polymers were processed.