A potentially general approach to aliphatic ester-derived PVC plasticizers with suppressed migration as sustainable alternatives to DEHP†
The safety of flexible polyvinyl chloride (PVC) materials is now being questioned, partially due to allegations that di-(2-ethylhexyl) phthalate (DEHP), the dominant PVC plasticizer, is an endocrine disruptor and a probable carcinogen. As sustainable alternatives, aliphatic ester-derived plasticizers feature low cytotoxicity, biodegradability, and renewability, but they can only partially replace DEHP in PVC formulations because they have a strong tendency to migrate. Here, using epoxidized fatty acid methyl esters and aliphatic diesters as representatives, we demonstrate that covalently attaching one short ester at each α-position of aliphatic esters via Claisen condensation with judiciously selected dialkyl carbonate significantly suppresses their migration from the PVC matrix. In certain scenarios, the engineered plasticizers even migrate at a rate comparable to, or improved beyond that of DEHP. This approach harnesses the α-proton, a structural feature shared by all aliphatic esters, and dialkyl carbonate, an established “green chemical”, thus providing a potentially general and green route towards DEHP alternatives with unprecedented performance that may contribute to sustainability of the old and oft-maligned PVC industry.