Preparation of nonmigratory flexible poly(vinyl chloride)-b-poly(n-butyl acrylate)-b-poly(vinyl chloride) via aqueous reversible deactivation radical polymerization in a pilot reactor

Abstract

Industrially-viable nonmigratory internal plasticization of poly(vinyl chloride) (PVC) is achieved by synthesis of the block copolymer poly(vinyl chloride)-b-poly(n-butyl acrylate)-b-poly(vinyl chloride) (PVC-b-PBA-b-PVC) by aqueous single electron transfer degenerative chain transfer living radical polymerization (SET-DTLRP). The introduction of a temperature step (42 °C to 80 °C) in the synthesis of PVC-b-PBA-b-PVC block copolymers from PBA macroinitiators resulted in materials with better overall performance than the commercial flexible PVC. The resulting copolymers were fully characterized by 1H NMR, SEC, SEM, TGA, DSC and DMTA to determine the composition, molecular weight, dispersity, morphology, thermal and mechanical properties, and compared with those of commercial formulations prepared with PVC and dioctyladipate (DOA). Most importantly, the plasticizing moieties of the PVC-b-PBA-b-PVC block copolymers are covalently bonded to the polymer, resulting in no migration upon extraction under conditions where DOA is readily extractable. Unlike commercial materials, the PVC-b-PBA-b-PVC block copolymers showed that the properties remain intact after extraction with n-hexane.