STUDY ON TOP LAYER STRUCTURE OF COMPOSITE MEMBRANES

The study of composite membranes with top layers of different thicknes s is essentially a method of integral layer scanning. Two-layer compos ite membranes were formed by coating polymer solution on porous suppor t. Poly(phenylene oxide) (PPO) of different molecular weight and sulfo nated PPO were used as top layer polymers. Gas transport properties we re examined by gas chromatography and used for calculation of resistan ce and specific resistance of gas flow through a composite membrane. A ccording to the resistance, the top layers of composite membranes are very inhomogeneous through their thickness. The results were explained by deformation-orientational order which appears during the formation of thin films on a porous support. The interaction between the polyme r chains of top layer and the surface of support determines multizone structure of the top layer. (C) 1998 Elsevier Science B.V.