Development of Eco-Friendly Thermosetting Resins From Zein and Diglycidyl Ether of Vanillyl Alcohol. A Step Toward Sustainable Materials

Abstract

Herein, bisphenol A-free, biobased, and sustainable thermosets were obtained for the first time by using two naturally derived compounds. Zein, a renewable biopolymer extracted from maize, exhibited excellent reactivity and versatility, while the diglycidyl ether of vanillyl alcohol (DGEVA), a biobased epoxy monomer derived from vanillin, served as a sustainable alternative to petrochemical epoxides. By chemically integrating Zein into DGEVA thermosetting networks, environmentally friendly resins with excellent thermomechanical properties were developed. A comprehensive analysis of seven formulations, incorporating up to 30 wt.% Zein, provided critical insights into the relationship between protein content and resin properties. Differential scanning calorimetry (DSC) analysis highlighted a strong interaction between Zein and DGEVA's epoxy groups, resulting in significantly higher polymerization enthalpies compared to neat DGEVA homopolymerization. This indicates the formation of robust crosslinked networks driven by Zein's multifunctional groups. Dynamic mechanical analysis (DMA) demonstrated substantial improvements in the thermosets’ glass transition (T_g), with values increasing from 52°C in neat DGEVA to 73°C in DGEVA/30% Zein systems, indicating enhanced stiffness and thermal performance. Furthermore, thermogravimetric analysis (TGA) confirmed good thermal stability of the bioresins, with degradation temperatures exceeding 300°C. Beyond these technical achievements, this study underscores the broader significance of incorporating Zein, a byproduct of corn agriculture, into biobased thermosets.