Polymer matrix–clay interaction mediated mechanism of electrical transport in exfoliated and intercalated polymer nanocomposites

We report significant results on charge transport phenomena in the exfoliated and intercalated phase of polymer nanocomposite (PNC). X-ray diffraction and transmission electron microscopy results have provided convincing evidence of exfoliation at lower clay loading (x 5 wt%) in the PNC. Fourier transform infrared (FTIR) spectrum indicated lowering of anion symmetry from Oh to C4ν/C2ν/C3ν (depending on mode of cation interaction with counter ion). Substantial jump in electrical conductivity (~110 times) at room temperature has occurred on nanocomposite formation in sharp contrast to that of the polymer salt (PS) complex film. Large conductivity enhancement (10−3 S cm−1) is attributed to clay-induced interaction with PS matrix whose origin lies in polymer–ion, ion–ion, ion–clay, and polymer–ion–clay interaction evidenced in the FTIR results. An excellent correlation of conductivity with fraction of free anion and polymer glass-transition temperature agrees well with conductivity enhancement at specific clay loading. A model for charge transport phenomena is proposed to explain clay-induced ion dynamics. The conceptual basis of the model seems consistent with experimental results.