POSTINTERCALATIVE POLYMERIZATION OF ANILINE AND ITS DERIVATIVES IN LAYERED METAL PHOSPHATES

The formation of polyaniline in the layered metal phosphates, alpha-Ti(HOPO3)(2) . H2O, alpha-Zr(HOPO3)(2) . H2O, and HUO2PO4 . 4H(2)O is reported. Aniline and N-phenyl-1,4-phenylenediamine (PPDA) are intercalated in the layered phosphates to form the precursors for polymerization. X-ray diffraction patterns show interlayer expansions with titanium phosphate and zirconium phosphate, consistent with a bilayer of these molecules in the gallery. In contrast, only a monolayer is intercalated in uranyl phosphate. After thermal treatment at 130 degrees C in air, the intercalated aniline and PPDA are slowly polymerized by ambient oxygen. The formation of polyaniline was confirmed by FT-IR, UV/vis and EPR spectroscopies as well as magnetic susceptibility measurements. Following polymerization, the interlayer spacing slightly increases from 10.46 to 11.8 Angstrom for anilinium/uranyl phosphate but dramatically decreases from 28.3 to 20.5 Angstrom for PPDA/Zr(HOPO3)(2) and from 18.87 to 13.25 Angstrom for anilinium/Ti(HOPO3)(2), suggesting a monolayer of polyaniline inside the uranyl phosphate and titanium phosphate structures but a bilayer in Zr(HOPO3)(2). Gel permeation chromatography was used to determine the MW of the intercalated polyaniline. Prolonged heating in air results in cross-linked polymer in the galleries. All compounds are insulators.