Study On Preparation And Properties Of Hydrophobic Nano-TiO₂

The single surface modification and compound surface modification of nano-TiO₂ was studied by using nano-TiO₂ as raw material,water as solvent,hexamethyldisiloxane, methyltrimethoxysilane and 3-chloro-2-hydroxypropyl trimethyl ammonium chloride (CHPTMA) as modification agent,by wet method in this paper.The effect of factors such as kinds of modified agent,amount of modified agent,concentration of milk,reaction temperature,reaction time and pH value on surface modification degree of nano-TiO₂ was investigated.The surface modification effect of nano-TiO₂ was measured by wetting property,lipophilic degree,hydroxyl number on surface of the nano-TiO₂.The results through investigating single surface modification of nano-TiO₂ were showed that nano-TiO₂ could be modified by hexamethyldisiloxane,dimethyldichlorosilane, methyltrimethoxysilane and octanol.The wetting property of nano-TiO₂ is improved obviously in organic solvent after nano-TiO₂ being modified by Hexamethyldisilazane.The better modifying conditions were obtained.These process conditions are amount of modification agent 15%,concentration of milk 30%,reaction temperature 90℃,reaction time 1 h and pH value 5.The results through investigating compound surface modification of nano-TiO₂ were showed that the modified nano-TiO₂ has better hydrophobic performance than single modified nano-TiO₂.The better modifying conditions were obtained:amount of modification agent 15%,concentration of milk 30%,reaction temperature 90℃,pH value 5 and reaction time 1 h.Nano-TiO₂ was modified by CHPTMA,the better modifying conditions were obtained:amount of modification agent 20%,concentration of milk 30%,reaction temperature 90℃,reaction time 2h and pH value 7.The results through antimicrobial test showed that the gauze with nano-TiO₂ can prevent it mildewing;The nano-TiO₂ modified by quaternary ammonium salt did not change the inherent antimicrobial performance of unmodified nano-TiO₂,on the contrary,adding the antimicrobial scope of unmodified nano-TiO₂,namely,having antimicrobial performance in the dark. It was showed through measuring sedimentation of nano-TiO₂ with different lipophilic degree in ethanol and water,water contents of storage as well as influence on viscosity of paraffin that the more lipophilic degree of nano-TiO₂,the better the solubility in organic solvent,the less the water content.It was proved by the infrared spectra that some of hydroxyls on nano-TiO₂ surface are substituted by organic group of modification agent.It indicated through SEM that the more lipophilic degree of nano-TiO₂,the better its dispersibility,the less size of agglomeration.