Mechanism-Inspired Synthesis of Poly(alkyl malonates) via Alternating Copolymerization of Epoxides and Meldrum’s Acid Derivatives

Direct incorporation of malonate units into polymer backbones is a synthetic challenge. Herein, we report the alternating and controlled anionic copolymerization of epoxides and Meldrum's acid (MA) derivatives to access poly(alkyl malonates) using (<i>N,N'</i>-bis(salicylidene)phenylenediamine)AlCl and a tris(dialkylamino)cyclopropenium chloride cocatalyst. This unique copolymerization yields a malonate-containing repeat unit while releasing a small molecule upon MA-derivative ring-opening. Mechanistic and computational studies reveal that the nature of the small molecule released influences overall polymerization kinetics, side reaction behavior, and molecular weight control. Controlled copolymerization of MA derivatives with a range of epoxides ultimately yields a library of new poly(alkyl malonates) with diverse and tunable thermal properties.