Multi-functionalization of gallic acid. Synthesis of a novel bio-based epoxy resin

Novel biobased epoxy thermoset was synthesized from gallic acid, a phenolic acid encountered in various plants, both in its simple form and as a part of gallotannins. The functionalization of gallic acid was carried out using a two-step synthesis involving the allylation of OH groups followed by the epoxidation of resulting double bonds. The performance of two oxygen transfer agents (meta-chloroperbenzoic acid (mCPBA) and methyl(trifluoromethyl) dioxirane generated in situ from 1,1,1-trifluoroacetone and oxone) was evaluated in the epoxidation of the allylic double bonds. The glycidyl derivative of gallic acid (GEGA) obtained from mCPBA epoxidation was cured in epoxy polymer formulation with isophorone diamine (IPDA). The thermal and mechanical preliminary analyses showed that this new epoxy network based on GEGA displayed interesting properties compared to the epoxy polymer formulated with commercial diglycidyl ether of bisphenol A (DGEBA). A higher glass-transition temperature of GEGA/IPDA epoxy resin indicates a higher crosslinking density of this network.