Synthesis and Characterization of Bio-based Epoxy Resins Derived from Vanillyl Alcohol

Vanillyl alcohol, a lignin derived aromatic diol, is a potential platform chemical for the production of renewable epoxy thermosets. A bio-based bisphenolic analogue, bisguaiacol (BG), was synthesized via electrophilic aromatic condensation of vanillyl alcohol and guaiacol, from which diglycidyl ether of BG (DGEBG) was prepared. In addition, three single aromatic diglycidyl ethers were synthesized from vanillyl alcohol (DGEVA), gastrodigenin (DGEGD), and hydroquinone (DGEHQ). All epoxies were characterized via H-1 NMR, C-13 NMR, FTIR, MS, and GPC. Dynamic mechanical analyses of the epoxies by themselves or blended with a commercial epoxy resin and cured with a diamine were conducted to determine the effect of the methoxy and methylene moieties on polymer properties. The thermomechanical results indicate that the methoxy lowers the glass transition temperature (T-g) yet increases the glassy storage modulus at 25 degrees C, while the methylene spacer between the aromatic ring and the epoxide further lowers the T-g in cured epoxy-amine systems.