Electric field responsive chitosan-poly(N,N-dimethyl acrylamide) semi-IPN gel films and their dielectric, thermal and swelling characterization

The electroresponsive, dielectric and swelling behavior of semi-interpenetrated polymer network (semi-IPN) gel films prepared from chitosan (CS) and N,N-dimethyl acrylamide (DA) were investigated and compared with those CS film. CS-DA semi-IPN films were also characterized by Fourier transform infrared, x-ray diffraction and differential scanning calorimetry measurements. The electrosensitivity of CS-DA films to an electric field was investigated by determining their bending at 8 V in (0.05 M/0.1 M/0.15 M) NaCl solution. Equilibrium swelling values of CS-DA films both in distilled water and buffer solution with pH = 2:2 decreased with poly-DA (PDA) content of the films. While the maximum decomposition of CS film took place at about 296 degrees C, the presence of PDA in CS-DA semi-IPN films reduced the thermal stability, and their maximum decomposition temperature shifted from 261 to 240 degrees C with the increase in PDA content. In addition, the PDA network led to a decrease in the dielectric constant (epsilon'), dielectric loss (epsilon '') and conductance (sigma) of CS-DA semi-IPN films in the frequency range between 12 Hz and 100 kHz. The values of electric modulus and impedance, and Cole-Cole plots confirmed that the conductance values of CS-DA films are lower than that of CS film. The PDA network also led CS-DA films to respond more slowly to electric field. The increase in NaCl concentration in the bending medium increased the response rate of CS-DA films to an electric field. The final bending angle of all CS-DA films was 90 degrees, and it was not dependent on either NaCl concentration or PDA content of the films.