Grafting polyethylene glycol dicrylate (PEGDA) to cell walls of poplar wood in two steps for improving dimensional stability and durability of the wood polymer composite

Polyethylene glycol (PEG) treatment is an effective approach to endow wood with higher dimensional stability (DS), which is still a concern under humid conditions. In this study, poplar wood was first treated with methacryloyl chloride to introduce methacryl groups in the cell wall. Then functional PEG served as modifier, and copolymerization was conducted in the second step to prepare PEG-diacrylate (PEGDA) modified samples. The resultant wood polymer composites (WPCs) were characterized by solid state NMR, field emission scanning electron microscopy (FE-SEM), and X-ray diffraction (XRD). The physical and mechanical properties of the WPCs were also evaluated, such as anti-swelling efficiency (ASE), water uptake, dynamic hydrophilicity (contact angles), and thermal stability. The results show that the copolymerized WPC achieved 51.4% ASE with leaching <3.0%. Moreover, the surface hardness and water resistance of the wood are also greatly improved.