Effect of water content in solvent on the critical temperature in the formation of self-assembled hexadecyltrichlorosilane monolayers on mica

It is found that the critical temperature in the formation of self-assembled n-hexadecyltrichlorosilane (HTS) monolayers on mica depends on the water content in the solvent dodecane. Under the condition of 35 ± 2 ppm water content in dodecane, the critical temperature is found at 31 ± 1 °C. When the water content in dodecane is lowered down to 13±2 ppm, no critical temperature is found in the temperature range of 10–55 °C. Our results indicate that the critical temperature is subject to the extent of hydrolysis of HTS molecules in bulk phase of solution. A reaction mechanism of monolayer formation is discussed.