Hallo Jeyalakshmi, kindly mention what is the expansion for OTMS. Is it Octyl trimethoxy silane. I hope it is a liquid. If it is treated with colloidal silica or fumed silica you may get the desired product. As it contain methoxy group in it, You may use Methanol as solvent. Any how, the contact angle of OTMS treated surface is not directed by the solvent.