Abstract: The copolymerization products of a-pinene (M₁) and styrene(M₂)were prepared with the catalyst system SbCl₃/AlCl₃ by changing the Sb/Al ratio, feeding monomer ratio,solvent and polymerization temperature.The compositions of the copolymerization products were quantitatively characterized by the method of the combination of micro-ozonization and thin-layer chromatography in terms of the contents of the homopolymers and the copolymers.The results show that it was easier to obtain the higher yield(up to 80%)of the pure copolymer with the complex catalyst system than with AlCl₃ alone.The F₁ values could be controlled between 30%～56%.The monomer reactivity ratios were determined under the polymerization conditions under which only pure copolymer of M₁ and M₂ was given by using Mayo-Lewis equation.The effects of various catalyst systems and polymerization conditions on the reactivity ratio were also investigated and it was found that the r₁ increase from 0.19 to 0.22～0.24 with the AlCl₃/SbCl₃ instead of AlCl₃,but the r₂ decrease significantly(from 5.00 to 1.20～1.92).On account of the r₂/r₁ value is decreased 4～6 times,the copolymerization of M₁/M₂ was changed into carried out with ease.It was supposed that this good copolymerization activity is attributed to its nonprotonic active species and the characteristic of the counteranion's structure.

Key words: Complex AlCl₃/SbCl₃ catalyst, Cationic copolymerization of α-pinene/styrene, Composition of copolymerization product, Monomer reactivity ratio determination