Thermal degradation behavior of polyaniline in polyaniline/Na+-montmorillonite nanocomposites

The thermal degradation behavior of polyaniline (PANT) in PANI/Na+-montmorillonite (Na+-MMT) nanocomposites prepared by in-situ intercalative polymerization of aniline into Na+-MMT has been investigated by thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The residual weight (TG curves) and its weight derivative (DTG curves) of the nanocomposites suggest that the PANT chains for PANI/Na+-MMT nanocomposites are more thermally stable than those for a simple PANI/Na+-MMT mixture. 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 PANI in the nanogalleries and also hindering the diffusion of degraded PANI from the nanocomposites. The shielding effect of the nanolayers is found to be significant as the Na+-MMT content in the PANI/Na+-MMT nanocomposites is increased. The XRD patterns of the nanocomposites after TGA measurements indicate that the basal spacing (d(001)) of the PANI/Na+-MMT nanocomposites is almost intact, implying that the thermal decomposition of the PANI chains is believed to occur mainly outside the silicate layers. (C) 2002 Elsevier Science Ltd. All rights reserved.