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研究了含水介质中,以枯基醇(CumOH)/三氟化硼(BF3)为引发体系的苯乙烯正离子聚合的特征,探讨了CumOH用量、体系中的水含量对苯乙烯正离子聚合转化率、聚合速率以及产物分子量及其分布的影响;并从分子模拟、分子量末端结构等角度探讨含水介质中苯乙烯正离子聚合的反应机理.结果表明,[H2O]≤0.11 mol/L条件下,苯乙烯正离子聚合具有可控聚合的特征;水对聚合速率、单体转化率以及分子量影响较小;[H2O]>0.11 mol/L,正离子聚合不能顺利进行.根据计算结果,CumOH/BF3引发体系相对于CumOH/H2O引发体系在参与引发所需要的活化能垒更小,说明CumOH/BF3更容易引发苯乙烯正离子聚合,这与实验结果一致.CumOH/BF3引发体系是通过活化C—O键来引发苯乙烯正离子聚合,水作为可逆终止剂有利于进行可控聚合,并得到了末端含有羟基的聚合物.
The characteristics of cationic polymerization of styrene initiated by CumOH / BF3 in aqueous media were studied. The effects of CumOH dosage, the water content in the system on the polymerization of styrene by cationic polymerization The rate of polymerization, the molecular weight and the distribution of the product were investigated. The reaction mechanism of cationic polymerization of styrene in aqueous medium was investigated from the aspects of molecular simulation and molecular structure. The results showed that under [H2O] ≤0.11 mol / L, The positive ion polymerization of styrene has the characteristics of controlled polymerization. Water has little effect on the polymerization rate, monomer conversion and molecular weight. [H2O]> 0.11 mol / L, the cationic polymerization can not proceed smoothly.According to the calculation results, CumOH / BF3 Compared with the CumOH / H2O initiator system, the activation energy barrier required for initiating the initiation system is smaller, indicating that CumOH / BF3 is more likely to initiate styrene positive ion polymerization, which is in agreement with the experimental results.CumOH / BF3 initiator system is activated by activating C- O bond to initiate the cationic polymerization of styrene, water as a reversible terminator is conducive to the controlled polymerization, and the end of the polymer containing hydroxyl.