Fully biobased epoxy vitrimers from phloroglucinol triglycidyl ether and 2,5-furandicarboxylic acid

Abstract

The use of non-renewable resources and hardly recyclable materials in the polymer industry and the related environmental concerns have led to intensive research for implementing more sustainable technologies compliant with the circular economy and green chemistry principles. Among the several possibilities, biobased vitrimeric materials to be used as an alternative to conventional thermosets represent an appealing solution. In this work, phloroglucinol triglycidyl ether was used as biobased epoxy resin in formulation with 2,5-furandicarboxylic acid. Different compositions were investigated by varying the carboxylic acid/epoxy molar ratio. The formulation with a ratio equal to 0.4 showed the best balance in terms of thermo-mechanical properties and pot life, and it was further optimized by adding a biobased reactive epoxy diluent from sorbitol at different weight percentages. The obtained crosslinked materials showed high gel content (> 99 %) and glass transition temperature in the 140–180 °C range, in line with standard oil-based epoxy systems. Due to the presence of both ester bonds and free hydroxy groups, the systems exhibited a vitrimeric response based on transesterification exchange reactions through an Arrhenius-type behavior, leading to a fast stress relaxation process. In addition, repeatable post-cure thermoformability and effective chemical recycling were demonstrated on tailored formulations based on these dynamic systems upon the incorporation of a biobased epoxy reactive diluent or an anhydride-based co-curing agent. This work provides the first example of fully biobased epoxy vitrimers based on 2,5-furandicarboxylic acid, further advancing the development of reusable and recyclable by-design biobased epoxy systems for sustainable manufacturing.