One-pot and industrial manufacturing of cardanol-based polyoxyethylene ether carboxylates as efficient and improved migration resistance plasticizers for PVC

Developing a bio-based plasticizer for poly(vinyl chloride) (PVC) with excellent plasticization, thermal stability as well as migration resistance remains a great challenge since there is a trade-off between compatibility and molecular weight. Herein, novel linear polymer cardanol-based polyoxyethylene ether carboxylates (CPEC) featured by high plasticization, excellent thermal stability and migration resistance were designed via ethoxylation of cardanol and sequent esterification with aliphatic acid (acetic acid, butyric acid, and oleic acid). The performances of poly(vinyl chloride) plasticized by cardanol-based polyoxyethylene ether carboxylates were highly structure-dependent, where the performances of poly(vinyl chloride) plasticized by ester bearing short alkyl group (methyl or propyl) excelled those of PVC plasticized by ester with heptadecyl group. Importantly, extensive experiments evidenced that the ductility, thermal stability and migration resistance of PVC blended with CPEC were significantly better than those of PVC plasticized by dioctyl phthalate (DOP). The excellent performances of PVC plasticized by CPEC could be ascribed to its repetitive oxethyl units, which played crucial roles in increasing its molecular weights, improving the compatibility with PVC, as well as imparting the flexibility of PVC. In particular, the PVC sample plasticized by cardanol-based polyoxyethylene ether acetate (CPEA) with the shortest alkyl ester demonstrated 1.6-fold increase of the elongation at break along with 20.8-fold increase of migration resistance in leaching tests compared with those of PVC specimen plasticized by DOP. This work opens up a simple and feasible strategy for fabrication of bio-based plasticizer featured by high plasticization and excellent migration resistance.