Methyltrichlorosilane polysiloxane filament growth on glass using low cost solvents and comparison with gas phase reactions

Fluorine free, transparent, superhydrophobic polysiloxane filament coatings on glass were successfully prepared using methyltrichlorosilane (MTCS) both via liquid phase reactions using standard hydrocarbons in an open system and gas phase reactions under controlled humidity environment. Wettability, morphology and transparency of the obtained coatings were characterized by contact angle measurements, scanning electron microscopy and UV–vis spectrometer transmittance tests respectively. Superhydrophobic polysiloxane nanofilament coatings were obtained for the first time in an open system using standard petroleum ether having advancing contact angle values (θa) between 156 and 168°. Surfaces having contact angle hysteresis as low as 9° were obtained by varying the reaction time and MTCS concentration in petroleum ether. On the other hand, the relative humidity was found to be the most important factor when compared with the factors such as reaction time and silane concentration to change the morphology and the contact angles of the coatings in the gas phase where 38% RH was found to be the optimum for the growth of polysiloxane nanofilament coatings on glass. Polysiloxane nanofilaments having diameters ranging from 34 up to 42 nm and θa values between 166 and 168° were obtained in the gas phase reactions. The transparency of the surfaces prepared in the gas phase was higher than the ones prepared in the liquid phase.