Abstract: The cationic polymerization of β-pinene was carried out with₁phenylethyl chloride as an initiator and the mixture of TiCl₄and tetraisopropoxytitanium[Ti(OiPr)₄] as a Lewis acid activator in CH₂Cl₂at -40 ℃. The polymerization with strong Lewis acid TiCl₄alone completed instantaneously and gave the polymers with broad molecular weight distributions.The addition of weak Lewis acid Ti(OiPr)₄, which alone had no catalytic activity for β pinene, retarded the polymerization by TiCl₄and led to polymers with narrower molecular weight distributions.When [Ti(OiPr)₄]₀/[TiCl₄]₀=1/3, the number-average molecular weight of the polymers increased in direct proportion to monomer conversion, and the molecular weight distribution of the polymers was narrow.The living nature of the polymerization was further demonstrated by monomer-addition experiments.¹H NMRanalysis of the polymers obtained at [Ti(OiPr)₄]₀/[TiCl₄]₀=1/3 showed that1-phenylethyl chloride served as an initiator and generated poly( β-pinene) chains with the CH₃CH(C₆H₅) head group and a tert-Cl tail group

Key words: Living cationic polymerization, β-Pinene, 1-Phenylethyl chloride, TiCl₄/Ti(OiPr)₄