No abstract

A series of polymer nanocomposite films based on intercalation of (PAN) 8 LiCF 3 SO 3 into the nanometric clay channels of an organomodified clay has been prepared using the standard solution-casting technique. The role of organoclay concentration on polymer-ion interaction, ion-ion interaction, and ion-clay interaction in clay-based nanocomposite films has been analyzed using Fourier transform infrared (FTIR) analysis. Substantial ion dissociation is observed even at a very low clay loading (1-2 wt.%) in the nanocomposites. FTIR results suggest the presence of both uncoordinated CF 3 SO 3 − (free-anions) and ion pairs in the nanocomposite evidenced by changes in CF 3 SO 3 − symmetry from C3ν to Cs and marked asymmetry in the profile of degenerate δ d (CF 3 − ) mode. The experimental results suggest a direct correlation of clay-assisted ion dissociation process with variation in conductivity (σ dc ) and glass transition temperature (T g ) as a function of clay concentration. A model has been proposed to explain the observed correlation on the basis of polymer-ion-clay interaction. The proposed scheme of ion transport mechanism appears to be consistent with the experimental observation.

No abstract

No abstract

A new combination of ionically conducting polymer-clay nanocomposites based on (PAN) 8 LiClO 4 þ x wt % montmorillonite (unmodified) clay has been prepared using the standard solution cast process. X-Ray diffraction (XRD) analysis reveals strong interaction of polymer salt complex (PS) with the montmorillonite matrix evidenced by changes in d 001 spacing of the clay and enhancement in the clay gallery width on composite formation possibly due to intercalation of polymer-salt complex into nanometric clay galleries. Evidences of such an interaction among polymer-ion-clay components of the composite matrix has also been observed in the Fourier transform infrared (FTIR) spectrum results. FTIR results clearly indicated cation (Li þ ) coordination at nitrile (CBN) site of the polymer backbone along with appearance of a shoulder suggesting strong evidence of polymer-ion interaction. Addition of clay into the PS matrix has been observed to affect ion-ion interaction resulting from ion dissociation effect at low clay loading in the PNC films. Complex impedance spectroscopy (CIS) analysis has provided a response comprising of a semicircular arc followed by a spike attributed respectively, to the bulk conduction and electrode polarization at the interfaces. Electrical transport appears to be predominantly ionic (t ion ¼ 0.99) with significant improvement in the electrical conductivity and thermal stability properties. Figure 10. Complex impedance spectrum (CIS) of PNC films [(PAN) 8 LiClO 4 þ x wt % Montmorillonite (MMT)] of different clay concentration at room temperature.