Styrene copolymerization using diphenylzinc-additive initiator systems: styrene/p-substituted styrenes

Combined systems including diphenylzinc (Ph2Zn), a metallocene, and methylaluminoxane (MAO), have been employed to initiate the copolymerization of styrene (S) with p‐alkylsubstituted styrenes and with α‐olefins. The copolymerization processes depend largely on the comonomer, the nature of the metallocene included in the initiator system, the presence of Ph2Zn, the polymerization temperature and the solvent used. Titanocenes produced true copolymers for S/p‐substituted styrene, but not in S/α‐olefin copolymerization. On the other hand zirconocenes either did not copolymerize S/p‐substituted styrene or produced very low conversions, while they succeeded in copolymerizing S/α‐olefin, depending on the particular zirconocene employed. A low p‐methylstyrene (p‐MeS) content in the S/p‐MeS copolymer and a low p‐tertbutylstyrene (p‐ButS) content in the S/p‐ButS copolymer decreased Tm, making them easier to process material than s‐PS.