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

A facile and simple route to obtain organic–inorganic hybrid glass films based on polyphenylsiloxane (1 − x)PhSiO3/2–(x)Ph2SiO2/2 (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 ∝ η0.76, or as a function of the withdrawal speed (v) with H ∝ v0.5. 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.