Preparation and properties of polyphenylsiloxane-based hybrid glass films obtained from a non-aqueous coating sol via a single-step dip-coating

Abstract A facile and simple route to obtain organic–inorganic hybrid glass films based on polyphenylsiloxane (1 − x )PhSiO 3/2 –( x )Ph 2 SiO 2/2 ( x = 0, 0.1, 0.2 and 0.3) has been proposed. The method involves the preparation of a non-aqueous coating sol composed of the polysiloxane in acetone. The films from 1 to 17 μm thick were coated on silica substrate via a single-step dip-coating at room temperature prior to further heat-treatment. As the hybrid matrix remains stable in the solvent, the desired film thickness ( H ) can easily be obtained as a function of the viscosity ( η ) of the sol with H ∝ η 0.76 , or as a function of the withdrawal speed ( v ) with H ∝ v 0.5 . Homogeneous films (average surface roughness less than 20 × 10 −4 μm) of high optical quality (optical propagation loss estimated to be less than 1 dB cm −1 at the telecommunication wavelength) with refractive indices comprise between 1.5 and 1.6, stable against the ambient atmosphere were successfully obtained.