Morphological characterization and electrochemical/electrical properties of poly(N-vinyl carbazole)/montmorillonite composites

A series of poly(N-vinyl carbazole) (PNVCz)/sodium montmorillonite (Na ⁺MMT) and PNVCz/organo-MMT composite materials have been successfully prepared by in situ free radical polymerization with cerium ammonium nitrate (CAN) as initiator in the presence of inorganic nanolayers of hydrophilic Na⁺MMT or organophilic organo-MMTs, modified with octadecylamine (ODA) and trimethyl stearyl ammonium (TMSA). The synthesized materials were subsequently characterized by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC). The distribution of MMT layers in the PNVCz matrix was also studied through polarized optical microscope (POM). Their electrochemical and electrical properties were investigated by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). The results showed that the type of intercalation agent and mixing method was affected on the structures and properties of composite materials. Both the interlayer spacing of clays and glass transition temperature of PNVCz was increased nearly from 1.18 nm to 3.53 nm and from 140°C to 185°, respectively. Their conductivities also increased relatively to that of the PNVCz homopolymer (10^-11-10^-15 S/cm) and varied in the range of 10^-10-10^-5 S/cm, inversely dependent on the amount of MMT loading.