Thermal Degradation Behavior of Polythiophene-modified Montmorillonite Nanocomposite

Abstract

Polythiophene (PTh) nanoparticles was synthesized by cationic surfactant assisted dilute polymerization method using FeCl3 as oxidant. The physical characterizations of the synthesized PTh nanoparticles were studied by FT-IR and XRD, DSC, SEM. Polythiophene (PTh)/clay nanocomposites were successfully synthesized with montmorillonite modified with Cetyl-Trimethyle - Ammonium Bromide (CTAB) and Didocyl Dimet hyl-Ammonium Bromide (DDAB), 1bromohexadecane (MSAB). The thermal degradation behavior of polythiophene (PTh) in PTH/Na+-montmorillonite (Na+-MMT) nanocomposites prepared by in-situ intercalative polymerization of thiophene into Na+-MMT has been investigated by thermogravimetric analysis (TGA) and X-ray diffraction (XRD), SEM. It was found that the PTh obtained by cationic surfactant assisted dilute polymerization method had better capacitor performances than the same obtained by the conventional chemical and electrochemical polymerization methods. The nanocomposites suggest that the PTh chains for PTh/Na+-MMT nanocomposites are more thermally stable than those for a pure PTh. This improvement in the thermal stability for the nanocomposites is attributed to the presence of Na+-MMT nanolayers with a high aspect ratio acting as barriers, thus shielding the degradation of PTh in the nanogalleries and also hindering the diffusion of degraded PTh from the nanocomposites. The shielding effect of the nanolayers is found to be significant as the Na+-MMT content in the PTh/Na+-MMT nanocomposites is increased. The XRD patterns of the nanocomposites after TGA measurements indicate that the basal spacing (d001) of the PTh/Na+-MMT nanocomposites is almost intact, implying that the thermal decomposition of the PTh chains is believed to occur mainly outside the silicate layers.