HMS mesoporous molecular sieve was methyl-grafted by the chemical vapor deposition (CVD) method using trimethylchlorosilane (TMCS) and hexamethyldisilazane (HMDSZ), respectively. The samples were characterized by XRD, N2-adsorpton, FTIR, 29Si NMR and TG, respectively, and the hydrophilicity of samples was measured. The results show that the mesoporous characteristics of all samples are still kept after the methyl-grafting treatment using TMCS and HMDSZ while HMDSZ performs more effectively than TMCS because HMDSZ can graft more methyl-groups. The experiment results can be reasonably explained by the proposed grafting reaction mechanism. Si-OH was directly chlorinated by TMCS to form OH-containing silane and Si-Cl group. The volatilization of OH-containing silane decreased the grafting efficiency of TMCS and the hydrolysis of Si-Cl to form Si-OH indirectly retained the surface Si-OH of HMS.%通过气相沉积法,分别用三甲基氯硅烷(TMCS)和六甲基二硅氮烷(HMDSZ)对HMS介孔分子筛表面进行甲基接枝改性;分别采用XRD、N2-吸附、FTIR、29SiNMR和TG等手段对样品进行表征,并测定了样品的亲水性能.结果表明,两种硅烷都可以在HMS表面接枝,接枝后分子筛的介孔结构依然保持;但是,HMDSZ的接枝效果要明显优于TMCS,前者能接枝引入更多的甲基;拟定的接枝反应机理可以合理解释上述结果:Si-OH被TMCS直接氯化形成羟基硅烷和Si-Cl,羟基硅烷的挥发降低了TMCS的利用率,Si-Cl的水解(形成Si-OH)间接保留了HMS表面的硅羟基(Si-OH).
展开▼
