Some aspects of the anionic polymerization of p-methylstyrene

Abstract

The kinetics of the initiation and propagation of polymerization of p-methylstyrene on exposure to n- and sec-BuLi in benzene has been investigated. It is shown that the presence of the methyl substituent lowers the rates of these stages 2–3 times as compared with polymerization of styrene. The absorption band in the UV spectra of the living polymer was found to shift from 330 to 340 nm with increase in its intensity during polymerization on exposure to sec-BuLi. The reversiblity of the shift in the band on introducing a fresh portion of monomer was demonstrated. It is assumed that these phenomena are associated with the formation of complexes of the active centre with the monomer. When the “living” polymer is held for a long time decrease in the intensity of the band 340 nm is observed with the appearance of absorption in the region 300 nm probably related to transfer of the chain to the methyl groups of the polymers. It is shown that p-methylstyrene actively polymerizes on a sodium mirror. Unlike systems with a lithium counter-ion prolonged holding on the mirror reduces the intensity of the band of poly-p-methylstyryl sodium with λ_max = 340 nm with the appearance of absorption in the region 530 nm similar to isomerization of polystyryl sodium.