SI-29-NMR STUDY OF HYDROLYSIS AND INITIAL POLYCONDENSATION PROCESSES OF ORGANOALKOXYSILANES .2. METHYLTRIETHOXYSILANE

The hydrolysis and initial polycondensation processes of methyltrietho xysilane (MTES) have been investigated by high-resolution Si-29-nuclea r magnetic resonance spectroscopy (Si-29-NMR). MTES was hydrolyzed in the system with MTES:ethyl alcohol:water:HCl = 1:4:x:y; x = 1, 2, 3, 6 ; y = 1 X 10(-4), 1 X 10(-2). Signals due to end and middle groups of polysiloxanes formed sub-regions on the basis of the number of hydroxy l groups attached to silicon, and the sub-region for silicon possessin g more hydroxyl groups was observed at a lower field. Based on signal intensities, the signals due to the dimers (Me(HO)2SiOSi(OH)2Me and Me (HO)2SiOSi(OH)(OEt)Me) and the trimer (Me(HO)2SiOSiMe(HO)OSi(OH)2Me) ( Me = CH3, Et = C2H5) were identified.