微波辅助合成聚天冬氨酸

借助微波辅助手段，以天冬氨酸（A）为原料，在均三甲苯和环丁砜混合溶剂中，以磷酸（体积分数为85%）为催化剂进行聚合反应。考察了催化剂用量、微波功率、反应温度和反应时间等因素对聚琥珀酰亚胺（PSI）的产率以及分子量的影响；进一步对PSI进行水解反应，并用红外光谱对水解产物进行结构表征。结果表明：借助微波辅助加热手段，使得聚合反应时间大大缩短，由传统热缩合反应的3～5h缩短为20min左右，反应效率明显提高；随催化剂用量的增加，PSI的产率增加，分子量降低，但过多的催化剂存在会导致产率下降；微波功率增大，PSI产率与分子量均呈下降趋势；在微波作用下，聚合反应温度（170～200℃）明显低于传统热缩合聚合的温度，并随着温度的升高和反应时间的延长，PSI的产率和聚天冬氨酸（PASP）分子量均呈现明显增加。在合适的条件下，可制备出数均分子量为6000～20000，分子量分布为1.3～2.4的PASP产物。

Polycondensation of L-aspartic acid under microwave irradiation

The polycondensation of L-aspartic acid (A) was conducted in a mixed solvent of sulpholane and 1,3,5 trimethylbenzene with phosphoric acid (φ＝85%) as catalyst, using microwave irradiation. The effects of varying the dosage of phosphoric acid catalyst, microwave power, reaction temperature and time on the yield, average molecular weight and molecular weight distribution (MWD, M_w/M_n) of the resulting polymer products, poly(succinimide) (PSI) and poly(as partic acid), was investigated. The product polymers, were characterized by FTIR. The results indicated that, compared with the traditional method, under microwave irradiation the polymerization time could be significantly reduced from 3-5h to 20min, and the reaction temperature (170-200℃) required was also reduced. The yield and molecular weight increased with increasing reaction temperature and time. All the GPC traces of the poly(aspartic acid) products obtained with different concentrations of catalyst exhibited narrow and unimodal molecular weight distributions with number average molecular weight (M_n) from 6000 to 20000 and polydispersity from 1.3 to 2.4.