In situ polymerization-hydrolysis-condensation of γ-methacryloxypropyltrimethoxysilane in cell wall for improved physical properties of wood

Silane coupling agent with its special molecular structure is often used to connect organic and inorganic materials. Due to the hydrophobic nature, silane coupling agents are often applied in wood surface modification instead of cell wall. In this study, poplar wood was modified with γ-methacryloxypropyltrimethoxysilane (MPS) to improve the dimensional stability and mechanical properties of the wood through in situ polymerization and hydrolysis-condensation reactions. The SEM/EDS imaging showed that at low monomer dosage, PMPS was uniformly distributed in the wood cell walls, while parts of PMPS formed a film at the cell lumen surface when modified with high concentrations of MPS. FTIR results indicated that PMPS was grafted onto the wood fibers. The XRD of the modified wood showed that the MPS modification did not affect the crystallinity of the wood. The even-distributed polymers PMPS, together with the original hemicellulose and lignin, act as a binder between microfibrils and was proved to impede the swelling of wood more efficiently than ordinary polymer bulking. Compared with untreated wood, 5% MPS modified wood achieved an ASE value of 48.67 ± 4.65% with the WPG only 5.05 ± 0.48%. The impact strength of 30% MPS wood increased by 45.66% compared with the unmodified wood. The ability to improve both dimensional stability and high mechanical properties with PMPS provided a promising modification solution for the functional improvement of wood.