Poly(Imide-Siloxane) Films With Controlled Thickness

Polyimides containing siloxane moieties are used in some advanced applications. For example, these polymers can be employed as separation membranes in the form of self-standing, thin films. These products are formed by components of different polarities that have the tendency, at least partly, to separate in the final materials, with an impact on their final, bulk, and/or surface properties. The aim of this work is to study the dependence of the composition of the polyimide, poly(imide-siloxane) (PIS) and copolymeric PIS self-standing films differing in thickness on their properties. The important finding is that there is a rather large difference observed in the water contact angle on the film side oriented toward the air atmosphere during film preparation and that oriented toward a hydrophobic Teflon surface. Nevertheless, the gas transport properties of carbon dioxide and methane for these membranes are more influenced by the membrane composition than by the surface properties.