Synthesis of periodic polyolefins based on anionic alternating copolymerization†

To avoid sequence bias in the chain growth process of multicomponent periodic polymers, we reported an indirect method for the synthesis of strictly periodic polymers using nonpolar monomers. Using 1,1-diphenylethylene (DPE) as the comonomer, the precise sequence was achieved through living anionic polymerization (LAP) and hydrogenation. Four dienes (isoprene (Ip), 2,3-dimethylbuta-1,3-diene (DMBD), 2,3-diphenylbutadiene-1,3-diene (DPB), and 1-phenyl-1,3-butadiene (1-PB)) and an olefin with cyclic tension 1-cyclobutylvinylbenzene (CBVB) were copolymerized with DPE to prepare the alternating precursors. The periodic sequences of DPE–styrene–propylene (pd-DSP), DPE–propylene–propylene (pd-DPP), DPE–ethylene–styrene (pd-DES), DPE–styrene–styrene (pd-DSS) and DPE–ethylene–styrene–styrene (pd-DESS) were successfully synthesized with hydrogenation of these alternating precursors, and the nonpolar olefin units were successfully introduced into the periodic polymer. The results showed that the modification of the backbone carbon framework structure caused a consistent change in the thermal properties of the polymers. Moreover, the steric hindrance and arrangement density of the side chain substituents could significantly affect the performance of the periodic copolymers. This study provides a feasible method for the synthesis of non-polar periodic copolymers with precise periodic arrangements.