Reaction Induced Conformational Change in Polyindole: Polyindole/PVA Film as Biomimetic Sensors of Temperature and Electrical Energetic Conditions

Abstract

Conducting polymers can mimic the sensing characteristics of biological muscles through utilizing their unique electrochemical reactions. As these reactions occur, alterations in composition prompt changes in biomimetic properties, such as shifts in volume, brought about by the insertion of anions and solvent molecules, resulting in conformational movements. Similar to biological muscles, these electrochemical reaction senses the working variables affecting the reaction rate, through the same two connecting wires. The influence of working temperature and electrical energetic condition on the conformational movements of polyindole manifested as the cooperative actuation of the polymer chain is verified here using a polyindole-coated polyvinyl alcohol (PIN/PVA) film. Cyclic voltammetric (CV) studies revealed that the extent of reaction of polyindole varies linearly with temperature and scan rate. The logarithmic dependence of redox charge obtained from coulovoltammogram with inverse of temperature further proved the temperature sensing characteristics and the influence of temperature on the cooperative actuation of the film. The conformational relaxation increases as the temperature increases through hosting higher number of counter anions with the solvent molecule. The extension of the redox reaction was found to decrease as the scan rate increases. The double logarithmic relation between the consumed redox charge and the scan rate has proved that the electrical energetic condition can influence the conformational movement in a reversible manner. It is also verified from Chronopotentiometric (CP) studies that the consumed electrical energy during the reaction varies linearly with the change in temperature. The results suggest that the PIN/PVA film can act as a biomimetic macro molecular sensor of working temperature and electrical energetic condition as biological muscles do.