Novel bio-based epoxy resins from eugenol derived copolymers as an alternative to DGEBA resin

Abstract

A novel vinyl ether monomer from eugenol, 2-eugenoloxyvinyl ether (EEVE), was synthesized and copolymerized with cyclohexyl vinyl ether (CHVE) at three different weight ratios (25, 50 and 75 wt%) via carbocationic polymerization. Polymerization occurred exclusively through the vinyl ether groups leaving the allylic functionality of eugenol moieties available for epoxidation. Epoxidation of the copolymers resulted in epoxy resins with varying amounts of epoxy contents. Cured coatings and free films were produced from the epoxidized copolymers and from diglycidyl ether of bisphenol-A (DGEBA) resin as a reference via reacting with two amine curatives at elevated temperatures. The glass transition temperature of the networks derived from the Epoly(75EEVE-co-25CHVE) resin with 25 wt% CHVE monomer was lower (about 66 °C) than the networks from DGEBA resin (>120 °C), however, Epoly(75EEVE-co-25CHVE) networks showed better mechanical properties (modulus, elongation). The results showed that coatings derived from Epoly(EEVE-co-CHVE) copolymers are comparable in terms of hardness to DGEBA coatings. However, compared to DGEBA coatings which show very poor flexibility (0 % mandrel band), Epoly(75EEVE-co-25CHVE) showed excellent flexibility (32 % mandrel band) and higher base resistance (>3 months). These partially biobased epoxy resins derived from eugenol have the potential to be competitive with petroleum-based DGEBA resins in coatings applications.