Hierarchically-Ordered Electroactive Silica-Polyaniline Nanohybrid: A Novel Material with Versatile Properties

Poly(trimethoxy silylpropylaniline), a nanoporous (pore diameter of 2.4 nm), electroactive (stable reversible redox characteristics), electrochromic (yellow at -0.10 V, blue green at +0.50 V, and dark green at +0.70 V), and pH-sensitive, silica-polyaniline (PANI) hybrid material (designated as KGM-1) has been synthesized in powder form by a simple one-pot chemical synthesis as well as a thin nanolayered film by cyclic voltammetry. High-resolution transmission image of KGM-1 informs that the particles are spherical, with diameters in the range of 0.5-1.5 mu m. X-ray diffraction pattern of pristine KGM-1 confirms the combined presence of ordered silica network and PANI chains. The surface area of calcined KGM-1 is 40 m(2)/g (similar to 15 times higher than KGM-1), and the average pore size is 2.4 nm. The N-2 adsorption features also inform that PANI is present as a uniform layer within the pores of silica and because of that the silica pores are not completely blocked. The reversible redox transitions in PANI units and nanoporosity of KGM-1 are effectively used for the electrodriven loading/release of DNA or adenosine 5'-triphosphate. (C) 2010 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 48: 4537-4546, 2010