Syndiospecific styrene polymerization with CpTiCl3/MAO: Effects of the order of reactant addition on polymerization and polymer properties

Abstract Syndiospecific styrene (St) polymerization, catalyzed by the CpTiCl 3 /methylaluminoxane (MAO) system, was investigated using two different activation procedures. The polymerization parameters included polymerization time, temperature (∼25–100°C), ratio of [Al]/[Ti] (∼100–1000), and catalyst precursor concentration (∼0.5–10.0 × 10 −4 mol Ti/L). It was found that adding reactants in the order of (CpTiCl 3 + MAO) + St (Injection of Styrene mode) gave much higher monomer conversion rates, higher weight‐average molecular weights, and narrower molecular weight distributions than for the (St + MAO) + CpTiCl 3 (Injection of Catalyst mode). The former also yielded significantly higher syndiotacticity fractions. Differential scanning calorimetry measurements showed multiple peaks exhibiting polymorphism in crystalline syndiotactic polystyrene samples. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1449–1455, 2004