Anionic terpolymerization of 1,3-pentadiene, para-methyl styrene and para-tert-butylstyrene to produce alternating-random sequence copolymer with tunable composition

Abstract

The utilization of the “pentadiene-alternating strategy” offers a unique living anionic polymerization (LAP) routine to synthesize sequence-controlled polymers with well-defined alternating sequences. Moreover, due to the “active” site of the benzyl methyl group, para-methyl styrene (MST) homopolymer and copolymer can provide new approaches for the preparation of functional polymers. Herein, a new class of reactive MST-based copolymers and terpolymers with narrow molecular weight distributions and tunable composition distributions, have been prepared by LAP. The change of the instantaneous compositions in the copolymer throughout the conversion process is tracked by ¹H NMR monitoring the characteristic peak change of [PD]/[MST]/[TBS] (i.e. [C=C]/[methyl]/[ter-butyl]) monomer units. Interestingly, by controlling the feed ratio of comonomers (MST, 1,3-pentadiene = PD and para-tert-butylstyrene = TBS), the terpolymers with constant composition and gradient composition distribution can be obtained via a one-pot method. The copolymerization kinetic analysis and copolymer product characteristics are given. At last, the “bond-forming initiation” theory is proposed to interpret this unique terpolymerization behavior. To the best of our knowledge, the combination of “pentadiene alternating modules” and “MST copolymerization strategy” provides a very favorable reaction condition for active benzylmethyl group incorporation to obtain alternating sequences of quantitatively polar functionalized copolymers, as well as comb-shaped copolymers.