Adhesion and permeability of polyimide-clay nanocomposite films for protective coatings

A polyimide (PI)-clay nanocomposite was prepared from a solution of poly(amic acid), a precursor of 2,2-bis[4-(3,4-dicarboxyphenoxy)phenyl]propane dianhydride and p-phenylenediamine, and dodecylamine-montmorillonite. Fourier transform infrared spectroscopy, thermogravimetric analysis, X-ray diffraction, and atomic absorption spectroscopy were used to verify the incorporation of the modifying agents into the clay structure and the intercalation of the modified clay into the PI matrix. Both PI and PI-clay films were subsequently prepared by solution casting. The gas permeability, resistivity, and adhesion properties were determined. In the case of gas permeability, only a 3 wt % addition of clay reduced oxygen permeability to less than half that of unfilled PI. Furthermore, this hybrid showed an improvement in electrical resistivity because of the prevention of electrical tree growth by clay particles. More importantly, adhesion between the films and silicon increased with increasing clay content. (C) 2003 Wiley Periodicals, Inc.