Vinylidene Monomers Designed for Chemical Recycling

Abstract

Marine pollution caused by plastic wastes increased the demand for recyclable polymer materials. In this review, we focus on the chemical recycle of vinyl polymers and polyesters, as they dominate the plastics market. Despite the easy procedure of synthesis, vinyl polymers are difficult to decompose due to the carbon backbone. Therefore, selective regeneration of monomers from polyolefins are difficult. In contrast, poly (methyl methacrylate) (PMMA) prepared by controlled radical polymerization can be depolymerized to regenerate the monomer. On the other hand, we have developed new vinyl polymers that efficiently regenerate their monomer precursors by main chain scission starting from the hydrolysis of the side group. For chemical recycling of polyesters, quantitative scission of ester bond is required. Recycling of PET has already been commercialized, but a more efficient method of the ester bond cleavage is required. Therefore, easily recyclable polyesters have been developed. In contrast, we have reported new unsaturated polyesters with chemical recyclability that recovered the monomer species. Instead of the ester bond cleavage, conjugate substitution reaction of the allyl-substituted methacrylate skeletons in unsaturated polyesters were performed under ambient condition.