Structural Study of Al(acac)3 Catalyzed CH3SiO3/2 Gel

A transparent CH3SiO3/2 gel and an opaque one have been prepared from methyltriethoxysilane. Al(acac)3 is added to obtain the transparency. The two gels are studied by XRD, NMR and infrared spectroscopy. Some amount of silanols remains in the form of T2(CH3SiO(OH)) in the transparent gel, but few in the opaque gel. There is a diffraction peak reflecting intermolecular correlation in the XRD curves, which appears broader at a lower angle in the transparent gel than in the opaque gel. These results are discussed by assuming a larger hindrance in polymerization of silanols in the transparent gel.