Preparation and properties of polyimide-clay nanocomposite materials for anticorrosion application

A series of polymer-clay nanocomposite (PCN) materials that consist of organosoluble polyimide and layered montmorillonite clay were prepared by the solution dispersion technique. The organosoluble polyimide containing non-coplanar moiety in diamine monomer and flexible bridging linkages in dianhydride monomer was synthesized by chemical imidization. The as-synthesized PCN materials were characterized by infrared spectroscopy, wide-angle powder X-ray diffraction, and transmission electron microscopy. The organosoluble polyimide showed better corrosion resistance compared to polyaniline, poly(o-ethoxyaniline) and poly(methyl methacrylate) by using a series of standard electrochemical corrosion measurements of corrosion potential, polarization resistance, and corrosion current in 5 wt % aqueous NaCl electrolyte. Polyimide-clay nanocomposite materials incorporated with low loading of clay were found to further improve corrosion inhibition over pure polyimide. Effects of the material composition on the O-2/H2O molecular permeability, optical clarity, and thermal properties of polyimide-clay nanocomposite materials were studied by molecular permeability analysis, UV-visible transmission spectra, thermogravimetric analysis, and differential scanning calorimetry, respectively. (C) 2004 Wiley Periodicals, Inc.