茂金属催化苯乙烯间规聚合物的颗粒形态

Particle morphology of syndiotactic polystyrene prepared with homogeneous metallocene catalyst

以均相单茂钛化合物[CpTi(OPh)3和CpTi(OPhOMe)3]为主催化剂,配以烷基铝氧烷(MAO)和三异丁基铝(TIBA),进行了苯乙烯的本体间规聚合.研究发现,聚合过程中生成聚合物的快速结晶对于避免反应体系的凝胶化,制得颗粒状产物十分重要.但正因为这种结晶成核机理,使所得颗粒的形貌极不规整,调控也十分困难.聚合过程中sPS种子的加入没有明显改善生成聚合物的颗粒形态.但当聚合体系中引入少量其他聚合物后,得到了较为规整的sPS颗粒,尤其当加入的聚合物与无定形sPS热力学不相容时(如mEPDM),得到了十分规则的球状颗粒.

Syndiotactic polystyrene （sPS） was prepared by bulk polymerization with homogeneous metallocene catalystic system, Cp ＊ Ti（OPh）3 or Cp ＊ Ti（OPhOMe）3/MAO/TIBA. It was found that a fast crystallization of the produced sPS is very important to avoid gelation of the polymerizing mixture and prepare powdery product. But, it was due to crystallization nucleation mechanism that the morphology of produced particles was very irregular and extraordinarily difficult to manipulate. Adding a little sPS seed during polymerization did not improve particle morphology. However, regular particles with good morphology could be simply prepared by adding a little other polymer. When the added polymer （e. g. mEPDM） was immiscible with the amorphous sPS, spherical particles could be obtained.