Synthesis of Gallic Acid-Derived Plasticizers for Polyvinyl Chloride Featuring Excellent Plasticization, Thermo-Stability, and Migration Resistance

The development of a facile and environmental strategy for manufacturing a natural aromatic-derived plasticizer for poly(vinyl chloride) (PVC) featuring excellent plasticization, UV-shielding, and thermostability, together with migration resistance, is still a challenge. Herein, a series of gallic acid-derived polypropylene glycol monomethyl ether esters with natural aromatic rings (TGPME-n, n = 1, 2, or 3 referring to the number of methylethoxy units in the structure of TGPME-n) were developed as plasticizers for PVC via the simple esterification of gallic acid with polypropylene glycol monomethyl ether and sequent etherification with epichlorohydrin in a one-pot process without any HCl generation. Extensive experiments showed that the performances of PVC blended with TGPME-n were highly dependent on the number of methylethoxy units from TGPME-n, where the performances of PVC plasticized by TGPME-n with more methylethoxy units were better than those of TGPME-n bearing one. Benefiting from the strong interaction of aromatic and polar groups (epoxy, ethoxy, and ester groups) in TGPME-n with a PVC skeleton, plasticization, low temperature resistance, thermal stability, transparency, and UV-shielding as well as migration resistance of PVC plasticized by TGPME-3 with maximum methylethoxy units were superior to those of PVC blended with dioctyl phthalate (DOP), implying that TGPME-3 could be used as an attractive alternative to totally replace the toxic DOP. This study provides a simple and feasible strategy to fabricate a highly efficient natural aromatic-derived plasticizer for the PVC industry.