Ion transport model in exfoliated and intercalated polymer-clay nanocomposites

Transport properties of ion conducting polymer-clay nanocomposites (PNCs) are reported. Experimental results indicate the possibility of exfoliation at lower clay loading and intercalation with increase in clay concentration in the composite matrix. The intercalation of cation coordinated polymer into the nanometric clay galleries has been confirmed by XRD and TEM analyses. Convincing evidences of polymer-ion, polymer-clay, ion-ion and ion-clay interactions have been observed in FTIR results. The estimated fraction of free charge carriers has shown excellent correlation with measured conductivity. Substantial enhancement in d.c. conductivity in the PNC films relative to the polymer salt complex (PS) is attributed to clay induced interaction among the composite components. A model for conductivity enhancement is proposed to understand the ion transport process in exfoliated and intercalated PNCs. The conceptual basis of the model seems consistent with the experimental results. The ion transport number (t(ion)) for all the PNC films has been estimated to be >99%. An improvement in voltage stability has been observed with addition of clay. (C) 2010 Elsevier B.V. All rights reserved.