Development of an enhanced double-layer hydrophobic system for wood via MTMS cross-linking, lumen filling and MTCS surface treatment

Abstract

The widespread application of fast-grown timber species is hindered by their high susceptibility to water absorption, poor dimensional stability, and inadequate mechanical strength. In this study, poplar wood underwent a sequential impregnation process with methyltrimethoxysilane (MTMS) and an ammonia-ethanol mixture. This combined treatment allowed silane cross-linking with cell walls while also filling wood cavities, promoting the in-situ growth of nanoparticles. After the impregnation process, a subsequent surface treatment with methyltrichlorosilane (MTCS) was then performed to establish a hydrophobic surface layer. Through structural and surface modification, a novel double-layer hydrophobic system was constructed to enhance water resistance. The modified wood exhibits a surface water contact angle of 153.6° ± 0.5° and a 10-mm depth contact angle of 112.8° ± 0.6°, illustrating the effectiveness of the dual-layer hydrophobic structure. Compared to the control wood, the modified samples exhibited a 65.6 % reduction in 24 h water absorption and a 48.4 % decrease in volume swelling. Additionally, cross-linking and lumen filling considerably improved the mechanical properties of the modified wood. The double-layer hydrophobic system shows significant potential to extend the service life of wood and enhance its mechanical performance, paving the way for broader applications in moisture-sensitive environments.