含不同侧氨基密度的PLGA-(ASP-Diol)x-PLGA共聚物的合成与表征

以N-(苄氧羰基)-L-天冬氨酸和亚硫酰氯反应制备了N-苄氧基天冬氨酸酐,将其与不同链长的二醇(乙二醇、二缩三乙二醇、聚乙二醇200和600)缩聚,合成了含端羟基的天冬氨酸-二醇交替预聚物(ASP-Di-ol)x;以其为大分子引发剂,辛酸亚锡为催化剂进行丙交酯/乙交酯(摩尔比75∶25)开环共聚,合成系列含侧氨基的天冬氨酸-二醇-聚乙丙交酯PLGA-(ASP-Diol)x-PLGA]多元三嵌段共聚物.用FTIR,1HNMR,EA,DSC和GPC对共聚物结构进行表征.结果表明,影响预聚物分子量的主要因素不是二醇的分子量,而是其端羟基的活性.随着二醇链段长度增加,多元共聚物中氨基含量降低,玻璃化转变温度也明显下降.通过改变二醇链段的长度(或分子量)可有效地控制PLGA-(ASP-Diol)x-PLGA中侧氨基的密度及分布.

Nonlinear Optical Properties of Poly(p-phenylene vinylene) Derivative Modified by N+ Ion Implantation

A series of poly(ASP-Diol)-xs were prepared by polycondensation reactions of N-CBz-L-aspartic acid anhydride with diols of different molecular weights including ethylene glycol, triethylene glycol, PEG200 and PEG600, respectively. They were used as the macromonomer initiators respectively to synthesize biodegradable copolymers PLGA-(ASP-Diol)-x-PLGAs containing pendant amino groups with different contents by ring-opening copolymerization of lactide/glycolide(molar ratio 75/25). Their structures were confirmed by 1HNMR, FTIR, EA, DSC and GPC. The results indicate that the main factor that affects the molecular weights of the prepolymers is not the molecular weights of diols, but the activity of the end hydroxyl groups. With increasing the chain length of the diols, the content of amino groups in the copolymers decreased, and the glass translation temperature(T-g) decreased obviously, therefore, it is considered that the content and distribution of amino groups in the copolymers can be effectively adjusted by changing the chain length of the diols.