Alternating Copolymerization Realized with Alternating Transformation of Anion-Migrated Ring-Opening Polymerization and Anionic Polymerization Mechanisms

As a kind of well-defined monomer sequence distribution, an alternating sequence endows polymers with specific properties owing to the precisely repeating structure. In this study, we report a novel alternating copolymerization of 1,1-diphenylethylene (DPE) derivatives with 1-cyclopropylvinylbenzene (CPVB) by means of alternating transformation of anion-migrated ring-opening polymerization (AMROP for CPVB) and general anionic polymerization (AP for DPE derivatives) mechanisms. In particular, the kinetics of the elementary reaction in this copolymerization system were first investigated, and it was confirmed that alternating copolymerization with the ideal alternating copolymerization kinetics (kCD, kDC > 0; kDD, kCC = 0; thus, rC = rD = 0 at 20 °C) was achieved. Additionally, neither the lower reactivity of the DPE derivative nor the excess feeding of CPVB in the reaction substantially influenced the formation of alternating sequences. Furthermore, because the DPE derivatives (DPE, 1-[4-[N,N-bis(trimethylsilyl) amino]phenyl]-1-phenylethylene (DPE-NSi2) and 1-(4-dimethylaminophenyl)-1-phenylethylene (DPE-NMe2)) exhibited different reactivities, the sequence distributions of DPE and DPE derivative units in the chain can be regulated through terpolymerization with CPVB. Therefore, DPE units with random, gradient, and block distributions in alternating terpolymers, which cannot be achieved in general polymerization reactions because of kinetic limitations, can be well regulated based on the abovementioned alternating copolymerization system. Overall, this study inspires and promotes alternating copolymerization in the field of polymer chemistry.