Development of high‐performance wood based composites using microwave‐assisted deep eutectic solvent pretreatment, polymeric resin/silica impregnation and densification

Abstract High‐performance wood‐based composites were developed through combined microwave energy‐deep eutectic solvent (MWE‐DES) pretreatment, resin/silica impregnation, and high‐temperature densification to improve their mechanical, structural, and dimensional stability properties for advanced structural uses. Microscopic imaging, chemical composition, stability, and mechanical properties with basswood samples provided a comparative analysis of the test materials. The results show that the MWE‐DES treated basswood had a highly porous network structure with partial removal of lignin and hemicellulose. The bending strength of modified basswood was enhanced from 60.9 MPa of raw basswood to 83.2, 87.4, 99.9, and 105.8 MPa after treatment durations of 30, 60, 90, and 120 min., respectively. Furthermore, impregnating the delignified basswood with resin or silica significantly enhanced its bending strength, achieving 246 and 198 MPa, respectively. The high mechanical strength of treated wood composites is due to the combined effect of enhanced cell‐wall fibril bonding at the micro/nanoscale, strengthening with cured resin, and/or SiOSi bonding between wood fibrils and silica. Additionally, thermal stability, dimensional stability, and termite resistance of the treated wood composites were also improved. The recoverability of lignin, hemicellulose, and used DES were demonstrated. Highlights Microwave energy and deep eutectic solvent treatment partially delignified wood. Removing lignin and hemicellulose led to a highly porous wood cell wall structure. Resin/silica impregnation and densification modified macro/micro wood structures. Enhanced wood fibril‐fibril and fibril‐resin or silica bonding improved wood strength. Lignin, hemicellulose, and DES were recovered, promoting sustainability.