NANOMETER-SCALE STRUCTURE OF HECTORITE-ANILINE INTERCALATES

The inclusion of the organic guest aniline into Cu(II)-exchanged hecto rite thin films has been investigated. The subsequent polymerization o f aniline on the clay surface and in the intergallery regions are stud ied using scanning force microscopy (SFM), electron paramagnetic reson ance (EPR) spectroscopy, powder x-ray diffraction (XRD), and impedance spectroscopy;EPR and XRD data show that in addition to strong polymer ization of aniline on the clay surface, polymerization also occurs in the intergallery regions of the clay. Using standard lift-off techniqu es or razor cleaving, the exposed intergallery polyaniline is successf ully imaged for the first time using noncontract SFM in phase-contrast mode. The nearly two-dimensional polymer sheets formed in these regio ns exhibit none of the nanometer-scale grain of bundle structure commo nly associated with polyaniline synthesized using techniques such as e lectrochemical or vacuum deposition. The electrical response of the re sulting clay-conducting polymer composites is also investigated for th in films fabricated on 15 mu m interdigitated arrays. Preliminary resu lts indicate that these composite materials may be highly suitable as chemical sensors for a variety of important gases and vapors such as e thanol and hexane. (C) 1997 American Vacuum Society.