Fabrication of amphiphobic softwood and hardwood by treatment with non-fluorinated chemicals

Amphiphobic wood has successfully been fabricated using a combination of O2 plasma surface activation and coating of pre-hydrolyzed methyltrimethoxysilane (MTMS). The effect of O2 plasma activation on surface chemistry and surface roughness was investigated using X-ray photoelectron spectroscopy and laser scanning confocal microscope profilometry, respectively. Pre-hydrolyzed MTMS was used to impart oleophobicity to both softwood and hardwood samples with tunable hydrophilicity by adjusting the sonication time during pre-hydrolysis. Depending on hydrolysis time, the coated wood samples display wetting behavior ranging from superhydrophilic/oleophobic (immediate water absorption; motor oil contact angles 63.5° for hardwood and 62.4° for softwood) to amphiphobic (water contact angles 104.3° for hardwood and 91.1° for softwood; motor oil contact angles 68.7° for hardwood and 63.9° for softwood), without affecting visual appearance of the wood. For all plasma-activated MTMS-coated wood samples, no absorption of motor oil is observed for several months, indicating stable oil resistance. The intrinsic porosity of wood is also partially retained after coating.