抄録
In the present work, the authors studied the effects of thermal treatment temperature and thermal treatment duration on endowment of a hydrophobic property to TiO2 treated with alkyltrimethoxysilane solutions by a dry method. Also, the relationship between M value, a parameter of hydrophobic property, and fixation of ATMS onto TiO2 was examined. The main results obtained are as follows :
(1) M values of TiO2 treated with n-BTMS and n-PTMS solutions increase with the increase in time elapsed, in another words, average polymerization degree, and finally reach a stagnant stage. The elevation of thermal treatment temperature and its duration also positively affect the M value of TiO2. On the other hand, the M value of TiO2 treated with n-DTMS was kept constant despite the change in thermal treatment conditions.
(2) Amounts of fixed n-BTMS or n-PTMS onto TiO2 treated with these solutions increase with the increase in average polymerization degree. Since M value increases with the elevation of temperature even at the same level of fixation amount of coupling agent, it is assumed that the elevation of temperature affects the condensation onto the TiO2 surface.
(3) ATMS Oligomer of lower molecular weight evaporated during the mixing and thermal treatment processes of TiO2 and ATMS solutions. This phenomenon was suppressed with the increase in average polymerization degree, resulting in the increase of fixed amount of ATMS onto TiO2. The decreasing sequence is expressed as n-PTMS>n-BTMS>n-DTMS. However, thermal treatment temperature is almost independent of vaporization amount.
