Fully Bio-Based Epoxy Resins from Liquefied Wood for Chemically Recyclable Wood Coatings

Epoxy resins are widely used in the coatings industry, yet their petroleum-based origin and crosslinked structures pose challenges for sustainability and recyclability. This study explores a cradle-to-cradle approach for bio-based epoxy wood coatings using the heavy fraction of liquefied wood (LW) as a renewable curing agent. LW, a lignin-like compound rich in aromatic structures, acts as a hydroxyl donor and reacts with biobased glycerol diglycidyl ether (GDE). This article presents the molecular characterization of LW by different techniques. It demonstrates that the resulting coating has a performance comparable to commercial bisphenol A epoxy-amine systems, and shows that the crosslinked product of LW and GDE can be depolymerized and recycled as aromatic polyol using the same liquefaction process. Importantly, this work highlights that the recycling process does not require removing the coating from the wood matrix. Instead, the coated wood, including both the wood and coating, can be recycled together through the same liquefaction process used to produce the LW. This LW-epoxy platform demonstrates the feasibility of creating wood coatings with improved recyclability, contributing to more sustainable practices in the coatings industry.