以二乙烯苯凝胶为核的星形高聚物的研究(Ⅰ)——星形聚苯乙烯的支化度及支化度分布

STUDY ON STAR POLYMER USING DVB GEL AS NUCLEUS (Ⅰ)——THE DEGREE OF BRANCHING AND IT’S DISTRIBUTION OF STAR POLYSTYRENE

本文以二元活性共聚物的模型来处理星形高聚物结合点的二乙烯苯凝胶,参考了活性二元共聚物的统计理论,得到了活性预聚物与二乙烯苯的反应产物的分子量与支化度的分布函数。在活性聚苯乙烯、对位二乙烯苯、正丁基锂与苯的反应体系中,进行了实验验证。结果表明:在配料比不大的情况下,理论分析与实验结果基本一致。在上述理论分析基础上,结合实验数据,得到了两个分布参数以及控制支化度及支化度分布的规律。

Using the statistic of living binary copolymer to treat the product of first method, we get the distribution of MW and degree of branching with different MW of Prepolymer.In the system of living polystyrene, p-DVB and benzene, we synthesize star polymer under high vacuum.In definite range of temperature, concentration of active species, experience data reveals: coefficient of polydispersity concids with theoretical result, furthermore no matter how wide MWD of prepolymer we have, the MWD of product still remains relative narrow. The degree of branching depends on initial material ratio (A=M_(0)/I_(0)) and the conversion of DVB’s second double bonds for branching fx. The relatinship is expressed by Eq. (10). As initial A increase, MWD is Broaden and deviation from Eq. (10) appears. The reason is there are some crosslinking took place between star polymers. Finally, gel point is reached. The critical ratio is 9 for low MW of living polymer, for high MW prepolymer, critical ratio shall be increased.In short, the model of living binary copolymer is good for treating star polymer in low initial ratio, it needs some correction for high ratio.