Stereospecific polymerization of styrene (St) was carried out with a rare earth catalyst system which consisting of rare earth carboxylate (RE)

alkyl aluminium (AL) and chlorinating agent (CL). The influences of catalyst systems on polymerization of styrene

kinetics and microstructure of the resulting polystyrene (PS) were investigated. The resulting molecular weight and its distribution

syndiotacticity

crystalline morphology and heat capacity of polystyrene were characterized by GPC

13C NMR

POM and DSC. The results show that styrene polymerization rate was first-order with respect to monomer concentration with RE/AL/chlorinated carboxylic ester (CE) catalyst system

and the apparent propagation activation energy was determined to be 34.4 kJ·mol-1. The multiblock atactic/syndiotactic PS products with high molecular weight (Mn

2.8×105—6.8×105 g·mol-1) and high melting point (Tm

160—260℃) could be obtained using RE/AL/CE. The catalytic activity could be further improved using the mixture of CE with chlorinated hydrocarbon (RX) as chlorinating agent. The apparent propagation rate constants were 3.9

5.6 and 9.2 times larger than those of RE/AL/CE at 50

60 and 70℃ respectively. The molecular weight of PS decreased to relatively low molecular weight (Mn

0.5×104—5.0×105 g·mol-1). The syndiotacticity of PS products was around 60% and their melting points ranged from 170℃ to 240 ℃.