Shape memory gels (SMGs) are one of the interesting and unique classes of soft and wet materials having wide application in actuator, sensor, optical and biomedical field. Thermal responsive SMGs have the ability to return from a temporary deformed state to its original shape under the influence of heat thus having the limitation of quick and proper control. On the other hand, conductive hydrogels have high potential in the field of medical treatment (drug release), electrochemistry (bioactive electrode coating), sensors and actuators. Our group has developed DMAAm-co-SA SMG with high mechanical strength, very good transparency and biocompatibility having potential application in different sectors [1]. Thus, we are motivated to combine the physical and mechanical properties of the SMGs with the electrical activity of an electroactive component in order to create unique prospects for the next generation materials. However, conductivity is not part of the inherent characteristics of the hydrogels, it can be provided by other materials or particles that are incorporated within the network of the hydrogels (e.g., conductive particles, conjugated polymers, etc.). Fully swollen hydrogels with conducting particles, such as graphite, carbon nanotubes or metallic particles incorporated in their structure typically show conductivity but conductivity is inversely affected by the swelling ratio, and the hydrogels exhibit brittle mechanical behavior [2]. In this work conductivity of the SMGs was achieved by chemically polymerizing EDOT (with PSS as the molecular dopant) within the tough SMGs fully swollen network. Here we could achieve conductive SMG with high swelling ratio and good mechanical toughness and studied their electric signal as a function of applied pressure or strain for application in sensor devices like pressure sensor or strain sensor.

References

[1] Amano, Y; Hidema, R; Gong, J; Furukawa, H. Chem Lett.,41, 1029-1031 (2012)

[2] Morita, S; Kawai, T; Yoshino, K. J. Appl. Phys., 69 (8), 4445−4447 (1991).