Synthesis And Characterization Of Organic/inorganic Composites Based On Polyaniline

Silica nanopartices were modified by silane coupling agent containing aniline moieties. The grafting of N-substituted aniline on surfaces of silica nanoparticles were conducted through hydrolysis of triethoxysilylmethyl N-substituted aniline (ND-42) and the following condensation reaction with silanol groups on surfaces of SiO2. Chemical anchoring of modified silica nanoparticles onto polyaniline (PANI) chains was conducted through electro-co-polymerization of aniline and N-substituted aniline grafted on surfaces of silica nanoparticles, and the resulting composite film displayed nanofiborous morphologies (ca.50 nm in diameter). Electrochemical studies showed that both PANI/ND42-SiO2 and PANI/SiO2 which was synthesis by the electro-co-polymerization of aniline and unmodified silica nanoparticles, displayed typical redox peaks of PANI in 0.5 mol·L-1 H2SO4, while PANI/ND42-SiO2 showed weaker degradation peak, suggesting higher electrochemical stability. The capacitor performances of PANI/ND42-SiO2 and PANI/SiO2 were studied by chronopotentiometry. PANI/ND42-SiO2 exhibited an average specific capacitance of 380 F·g-1 at a current density of 2 mA-cm-2, ca.40% higher than that of PANI/SiO2. The hybrid film also showed improved cyclic stability.Composite material PANI/KIT-6, with PANI filling in the 3-D interconnected pore channels of mesoporous silica, KIT-6, has been synthesized via a gas phase method. The composite formation and the presence of PANI inside pore channels of KIT-6 were indicated by X-ray scatter (SAXS), transmission electron microscopy (TEM) and N2 sorption isotherm.. SAXS patterns showed that the bicontinuous cubic mesostructure was retained very well after incorporation of PANI in the channels. The TEM images of PANI/KIT-6 showed ordered mesoporous structure, but the pictures were smeared and dark. N2 sorption isotherms showed decrease of surface area, pore volume and pore diameter, and a narrow pore size distribution, indicating the uniform incorporation of PANI in the mesoporous channels. The presence of PANI in the composite material was evidenced by FT-IR spectrum. The morphology of KIT-6 and PANI/KIT-6 were observed by scan electron microscopy (SEM). The images showed that the morphology of PANI/KIT-6 was similar to that of KIT-6, indicating the confinement of PANI within KIT-6 channels instead of locating on the outer surface. The thermal properties of PANI/KIT-6 and bulk PANI prepared similarly were measured by thermogravimetric anylysis in air. The bulk PANI decomposed between 280 and 630℃(with DTG peak at 458℃), while the encapsulated polymer decomposed slowly from 280 to 630℃(with DTG peak at 458℃), indicating improved thermal stability upon composite formation.PANI was confined in mesoporous carbon, C-46, to afford PANI/C-46-1, PANI/C-46-2 and PANI/C-46-3 through oxidative polymerization of aniline adsorbed into the pore channel of C-46 previously by immerging the mesoporous carbon in ethanol solution of aniline (the ratio of aniline to ethanol was 1:29,2:28 and 4:26, v/v). The structures of the composites were characterized by X-ray diffraction (XRD), TEM and N2 adsorption isotherm. XRD patterns showed that the composites retained 2-D hexagonally mesostructure. TEM images of PANI/C-46-1 and PANI/C-46-2 showed large domains of highly ordered strip-like and hexagonally arranged images, while TEM images of PANI/C-46-3 were a bit blurry. N2 sorption isotherms of PANI/C-46-1 and PANI/C-46-2 showed decrease of surface areas, pore volumes and pore diameters with narrow pore size distributions, but these two composites still possessed opened pore channels. T-plot analysis showed that the micropore surface areas and micropore volumes of PANI/C-46-1 and PANI/C-46-2 also decreased. These result indicated that PANI distributed both on the pore surface and in the framework of C-46. However, N2 sorption isotherms of PANI/C-46-3 showed that the pore channels were blocked. The composites and bulk PANI prepared under similar condition were characterized by FT-IR. Compared with the bulk PANI, vibrations of PANI/C-46-1 and PANI/C-46-2 shifted to lower wavenumbers, while no absorption bands shift was observed for PANI/C-46-3. The morphology of C-46 and the composites were observed by SEM. Virtually no difference in surface morphology between the C-46 host and the composites was observed, excluding the possibility that PANI was on the outer surface of the host material.