中文摘要：

聚，J-谷氨酸苄酯（PBLG）用体积分数为33％的HBr-醋酸溶液脱保护得到聚，J-谷氨酸（PLGA）．采用正交实验研究了温度、时间、溶剂及33％HBr-醋酸溶液用量在脱保护过程中对聚，J-谷氨酸分子量的影响．结果表明，反应温度越高，时间越长，溶剂二氯乙酸用量越大，PBLG降解越快，得到的PLGA分子量越小；33％HBr-醋酸溶液的影响则相反，随着33％HBr-醋酸溶液用量的增加，反应体系酸性减弱，PBLG溶解度降低，肽键断裂减缓，PLGA分子量也就相对较大．

英文摘要：

Poly（L-glutamic acid） （PLGA） was prepared by removing the benzyl groups from poly （y-benzyl L-glutamate） （PBLG） through 33% （volume fraction） HBr and acetic acid solution. Orthogonal test method was applied to study the effect of temperature, the reacting time, the quantity of the solvent and 33% HBr and acetic acid solution on the moleeular weight of PLGA during the process of deprotection. The result show that PLGA molecular weight would be decreased with the increase of the temperature, the reacting time, and the solvent quantity, for the degradation of PBLG. However, the effect of HBr was reverse, for the acidity of 33% HBr and acetic acid solution was weaker than that of dichloroacedic acid（Cl2HAc）, and PBLG could not be dissolved in 33% HBr and acetic acid solution.