Influences of pretreatment temperature on the surface silylation of diatomaceous amorphous silica with trimethylchlorosilane

• Published in: Journal of non-crystalline solids 2006-10, Vol.352 (36-37), p.3762-3771
• Main Authors: Yuan, Peng, Yang, Dan, Lin, Zhongyu, He, Hongping, Wen, Xiaoyan, Wang, Linjiang, Deng, Feng
• Format: Article
• Language: English
• Subjects: Chemistry; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Condensed matter: structure, mechanical and thermal properties; Exact sciences and technology; FTIR measurements; General and physical chemistry; Geology and archeology; Magnetic resonances and relaxations in condensed matter, mössbauer effect; MAS-NMR and NQR; NMR; Nuclear magnetic resonance and relaxation; Physics; Silica; Surface physical chemistry; Surfaces and interfaces; Thermal properties; Thermal properties of condensed matter; Water
• ISSN: 0022-3093; 1873-4812
• DOI: 10.1016/j.jnoncrysol.2006.05.035

Diatomaceous amorphous silica samples were modified by silylation using trimethylchlorosilane (TMCS). The resultant materials were characterized by using thermogravimetry (TG), 1H magic-angle spinning nuclear magnetic resonance (1H MAS NMR), Fourier transform infrared spectroscopy (FTIR) and chemical analysis. The degree of silylation was found to increase with the increasing temperature of thermal pretreatment on diatomaceous silica prior to silylation. Increment of the pretreated temperature leads to stepwise removal of physisorbed water followed by the dehydration of capping water that H-bonded with the surface silanols, resulting in exposure of more and more isolated and H-bonded silanols previously covered by water molecules. Among these exposed silanols, isolated silanols show high activity for silylation reaction but H-bonded ones show poor activity. The maximum degree of surface attachment of TMCS grafted onto the diatomaceous silica (about 1.81mmol TMCS groups per gram of silica) was shown in the sample pretreated at 1100°C, in which the amount of exposed isolated silanols get the maximum. The fundamental information derived from this work is of significance in well understanding the surface silylation reaction of diatomaceous silica and providing useful information for related industrial production.