Surface‐Inner Structure Engineering in Fast‐Growing Wood via Vacuum‐Dipping Impregnation for Fabricating High Performance Wood‐Based Composites

ABSTRACT Fast‐growing wood application is highly impacted by inherent hydrophilicity, poor dimensional stability and low hardness. This study proposed a new vacuum‐dipping‐impregnation (VDI) strategy with synergies of furfural resin nanoparticles (PFAnps) and biobased furfuryl alcohol (FA) to fabricate high‐performance wood‐based composites (WBC). Different from traditional vacuum‐pressure impregnation or surface coating, the VDI had vacuum impregnation for inner cell modification and dipping impregnation for surface cell modification. After treatment, the WBC (1FA/PFAnps wood and 2FA/PFAnps wood) had low weight gain (< 9%), but showed high resistance to surface wetting and inner immersion by liquid water and vapor moisture sorption. Moreover, 1FA/PFAnps wood exhibited remarkable superhydrophobicity, excellent self‐cleaning performance and high durability. This was because FA polymerization fixed PFAnps on wood surface, forming micro‐nano rough hydrophobic coatings. The dimensional stability was highly improved, and the maximum volume change decreased by 50%. The mechanisms were ascribed to surface‐inner cell structure engineering including hydrophobic FA resin and PFAnps coating formation, water path blocking, sorption site coverage and cell wall bulking. The hardness was also improved, with maximum increase reached 38%. The new fabrication and mechanism analysis provided references for resolving inherent defects of fast‐growing wood and synchronously improving surface and inner properties for sustainable value‐added application.