Abstract
Inverse microemulsion system of cetyltrimethylammonium bromide (CTAB) molecules is utilized for virtually monodispersed and controlled growth of HCl polyaniline (PANI) nanoparticles at room temperature (ca. 300 K). The templated electroconductive polymer reveals lamellar crystalline structure under X-ray diffraction signifying marked sub-chain alignment of the polymerized nanoparticles. The nanostructured polymer has spherically symmetric morphology in a size range of 2.0 nm to 6.0 nm under electron microscope examination. Gel permeation chromatography gives polydispersity index of 1.02 for nanostructured polymer in agreement with the size monodispersity transpired by electron microscopy. The d.c. electrical conductivity. sigma(dc) of PANI at room temperature is 10.11 S/cm whereas the variation of conductivity with temperature in the range 227-303 K reveals that the conducting mechanism can be considered as three-dimensional variable-range-hopping (3D-VRH). UV-Vis spectrum indicates two broad absorption bands due to polaron formation that contributes to enhanced electrical conductivity of the polymer. The fundamental absorption edge in the polymer is formed by direct allowed transitions to the extent that the optical band gap value was found to be 2.35 eV. The crystalline nanostructure and homogeneous doping attained in the cationic template of amphiphile are argued as contributing factors to the enhanced conductivity of the polymer.