Polymer-supported rare-earth catalysts for polymerization of styrene

A neodymium complex supported on an ethylene-vinyl alcohol copolymer (EVA · Nd) was prepared for the first time and the polymerization of styrene in the presence of a new type of catalyst system composed of this complex was studied. The new catalytic system [EVA · Nd Al(i-Bu)₃ CCl₄] (i-Bu = isobutyl) is characterized by its catalytic activity in comparison with that of conventional rare-earth catalysts. When [Nd] = 10⁻³ mol/L, [Styrene] = 5 mol/L, [Al]/[Nd] = 120 and [CCl₄]/[Nd] = 35, then the conversion to polystyrene (PS) was 55% in 6 h, and the catalytic activity reached 1972 g PS/g Nd which is higher by a factor of 45 than that of conventional rare-earth catalysts. The polymerization reaction shows a short induction period where the rate is first order with respect to the monomer concentration. The activation energy is 27,6 kJ/mol. This polymerization may proceed according to a free-radical or a Ziegler-type coordination mechanism.