Green and Fast Synthesis of Biobased Epoxy Foams at Room Temperature for Thermal Insulation

Polyurethane foams (PUFs) are one of the most efficient thermal insulation materials for building applications but mainly rely on harmful isocyanates and fossil-based feedstocks. Developing biobased, nonisocyanate alternatives reacting under mild conditions is essential for sustainable building materials. A biobased epoxy–amine system synthesized with glycerol triglycidyl ether (GTE) and triethylenetetramine (TETA) was optimized for rapid foaming at room temperature, with water acting as a catalyst. Prepolymerization of GTE with substoichiometric TETA amounts increased the viscosity of the system, enabling foam expansion with physical blowing agents (PBA). The effects of prepolymer composition, water content, PBA type and amount, and surfactant selection were investigated on foaming kinetics and foam morphology. Optimized formulations of epoxy foams were determined for three selected PBAs that rapidly expanded in less than 10 min. These biobased foams exhibited low densities of 90–160 kg.m –3 with a predominant open-cell morphology, and a low thermal conductivity (47 mW·m –1 ·K –1 for methyl acetate-blown foams), confirming their potential as insulation materials. This work demonstrates the feasibility of producing biobased epoxy foams under mild conditions, designed to possibly become credible alternatives to PUFs.