Anionic Self-alternating Polymerization of 1-(4-Vinylphenyl)-1-phenylethylene

A new AB-type difunctional monomer, 1-(4-vinylphenyl)-1-phenylethylene (1), was subjected to anionic polymerization using sec-butyllithium (s-BuLi), diphenylmethyllithium (Ph2CHLi), and diphenylmethylpotassium (Ph2CHK) in tetrahydrofuran at 0 °C. Soluble poly(1)s with predicted molecular weights and relatively narrow molecular weight distributions (Mw/Mn = 1.1–1.3) were quantitatively obtained. 1H and 13C NMR measurements revealed that two carbon–carbon double bonds in the styrene (A) and 1,1-diphenylethylene (DPE, B) frameworks in 1 were alternately consumed to construct the polymer main chain carrying unsaturated A and B units, respectively. This unique reaction mechanism of 1 was coined “self-alternating polymerization”. Quantitative hydrogenation of the unsaturated pendant groups in poly(1) with p-toluenesulfonyl hydrazide afforded a saturated polymer suitable for structural characterization. Poly(1) carrying the residual styrene and DPE pendant groups underwent heat-induced cross-linking to give an insoluble polymer.