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.

Automated summary

This study developed a simple and environmentally friendly method to synthesize a natural aromatic-derived plasticizer with excellent plasticization, UV-shielding, and thermostability for PVC. The performance of the plasticized PVC was highly dependent on the number of methylethoxy units in the plasticizer. PVC plasticized by the plasticizer with maximum methylethoxy units showed superior properties compared to PVC blended with toxic dioctyl phthalate (DOP), suggesting it can be an attractive alternative to replace DOP completely.