Biorefinery by-products and epoxy biorenewable monomers: a structural elucidation of humins and triglycidyl ether of phloroglucinol crosslinking

International audienceTThe need for thermosets from renewable resources is permanently increasing in order to find eco-friendly alternatives to petroleum-derived materials. Products obtained from biomass have shown to play an important role in this challenge. Here we present the structural characterization of new bio-based thermosets made by humins, a by-product of lignocellulosic biorefinery, and glycidylated phloroglucinol coming from biomass phenolic fraction. By employing ATR-FTIR and NMR spectroscopies, we elucidated the connections between these two systems contributing to clarify their molecular structure and their reactivity. We demonstrated that the resin curing takes place through ether bond formation between humins hydroxyl functions and phloroglucinol epoxides. Besides crosslinking, humins show a complex rearrangement of their furanic structure through different concomitant chemical pathways depending on the reaction conditions