Abstract: [Objective] The nano-Ag/TiO₂ wood-based composite materials were prepared by ultrasound assisted impregnation, and the chemical structure and microstructure were analyzed in this study, with the aim to provide a theoretical basis for the new type of nano mildew wood composite research.[Method] With six sodium hexametaphosphate and KH560 as dispersant, the Pinus sylvestris var. mongolica was reacted with nano Ag/TiO₂ to propagate nano-Ag/TiO₂ wood-based composite materials by ultrasonic assisted impregnation. The effects of ultrasonic power, time and nano Ag/TiO₂ concentration on the loading amount and leach-resistance of nano-Ag/TiO₂ wood-based composite materials were studied, and the performance of the crystalline, axial distribution, chemical structure, thermal stability and microcosmic structure of nano-Ag/TiO₂ wood-based composite materials were also investigated.[Result] 1) With the increase of ultrasonic power, the loading amount increased and then decreased. The loading amount of the 75 W ultrasonic wave treated samples increased by 31.5%. With the increase of ultrasonic power, the leach-resistance continued to increase. The leach-resistance of the 300 W ultrasonic wave treated samples increased by 7%. 2) Ultrasonic treatment time has little effect on the loading amount. With the increase of ultrasonic time, the leach-resistance increased and then decreased. The leach-resistance were reached the peak value of 77.73% at 30 min. 3) With the increase of nano-Ag/TiO₂ concentration, the loading amount continued to rise. When the concentration was 2%, the drug loading amount was 3.363 kg·m^-3. The leach-resistance was decreased with the increase of nano-Ag/TiO₂ concentration. When the concentration was 0.5%, the leach-resistance was 78.33%. 4) After ultrasonic assisted impregnation, nano Ag/TiO₂ successfully entered the interior of the wood and attached to the cell wall, the agglomeration phenomenon was reduced and the dispersion and immersion depth were significantly enhanced. 5) The modified nano-particles predicted in the tracheid and attached to the cell walls through hydroxyl hydrogen bond association. KH560 coupling agent grafting not only in TiO₂, and reacted with the hydroxyl groups of wood cellulose. 6) After penetrating into wood specimens, the nano-Ag/TiO₂ retained characteristic structures of anatase TiO₂ and thus retained photocatalytic activity. The decreased intensity of cellulose was due to the addition of nanoparticles having reduced the cellulose content in the specimen. 7) The thermal stability of nano-Ag/TiO₂ wood-based composite materials enhanced and the maximum degradation temperature increased by 11.8℃.[Conclusion] 1) Ultrasonic assisted treatment significantly increased the loading amount and the leach-resistance, and the ultrasonic power had a significant effect on the leach-resistance. 2) After ultrasonic assisted impregnation, nano-Ag/TiO₂ successfully entered the interior of the wood and attached to the cell wall, some of nano-Ag/TiO₂ reacted with the hydroxyl groups of the wood, and the others were connected with wood by KH560. 3) The thermal stability of nano-Ag/TiO₂ wood-based composite materials was improved.

Key words: nano-Ag/TiO₂, ultrasonic assisted impregnation, wood modification, wood-based composite materials