External stimuli responsive characteristics of epoxy-polyamide/starch blend films

Polymeric films of varying crosslink densities and of different molar-concentrations were prepared from the epoxidized oil/diglycedyl ether of bis-phenol A (DGEBA) epoxy/polyamide/starch by blending at ambient temperature. The influences of external stimuli such as pH, temperature, ionic strength of the swelling media, and the type of buffer on the equilibrium swelling properties were investigated. Polymeric films showed a typical pH and temperature response such as low-pH and low-temperature have maximum swelling while a high-pH and high-temperature show almost complete deswelling. A change in the ionic strength of the swelling solution from 0.01 to 0.2 M caused a decrease in the equilibrium degree of swelling of polymeric films. Oscillatory swelling was also observed and investigated in response to changes in the pH of the solution. The morphology of selected polymeric films were explained by scanning electron microscopy (SEM) and correlated with mechanical strength.