Physical transitions and nascent morphology of syndiotactic polystyrene in slurry polymerization with embedded CpTi(OMe)3/methyl aluminoxane catalyst

The physical transitions and nascent morphology of syndiotactic polystyrene (sPS) synthesized over heterogeneized embedded Cp^*Ti(OMe)₃/MAO catalyst in n-heptane slurry polymerization have been investigated. The homogeneous metallocene catalyst is heterogenized by embedding active titanium sites into an sPS prepolymer phase. At low styrene concentrations, the reaction mixture is well-dispersed slurry of sPS particles and at high styrene concentrations, swollen sPS particles form aggregates that become a wet powder phase. For a wide range of styrene concentrations, no global gelation occurs with the embedded catalyst. Complex nascent morphology of sPS polymers is also presented. Scanning electron microscopic images show that spherical as well as irregular-shaped microparticles, films, and fibers are formed and that particle generation and growth mechanisms are different from that of heterogeneously catalyzed α-olefin polymerization processes.