Cationic polymerization of β-pinene,styrene and α-methylstyrene

Molecular weight distributions determined by gel permeation chromatography demonstrate that α-methylstyrene copolymerizes with both β-pinene and styrene, forming both bi- and terpolymers. The composition of precipitated polymer versus crude polymer, as determined by nuclear magnetic resonance, suggests that β-pinene and styrene also copolymerize. Extraction of the latter bipolymer of β-pinene and styrene with acetone gives only a small amount of insoluble β-pinene homopolymer, confirming that β-pinene and styrene copolymerize in m-xylene. GPC analysis shows that each copolymer contains some homopolymer. A comparison of M _n with molecular weight calculated from NMR analysis, assuming chain transfer to solvent, indicates that chain transfer is the predominant method of forming dead polymer. The carbonium ions of the growing chain tend to transfer to solvent with increasing ease in the order β-pinene, styrene, and α-methylstyrene.