Tough Polyampholyte Hydrogels: Effect of Dialysis and Their Applications in Stretchable Electronic Skins

Abstract

Tough hydrogels are an emerging class of advanced materials that have resolved the long-standing problem of brittleness and fragility in conventional hydrogels. Their superior mechanical performances enable several unprecedented applications in bio-integrated electronics, surgical glues, and soft sensors and actuators. Polyampholyte (PAm) hydrogels are a sub-class of tough hydrogels which are formed by inter/intra chain ionic complexes between counter charged functional groups present on the polymer chains. The unique chemistry and structure of PAm hydrogels make them highly tough, resistant to biofouling, self-healing and adhesive on various surfaces. In this thesis, we have explored the potential of these tough PAm hydrogels as a key material for energy storage devices and for wearable electronics. Overall, this thesis has been divided into two sections. In the first section, we have emboldened the idea of using tough PAm hydrogels as gel electrolyte for energy applications by showing their ability to maintain good mechanical properties while delivering high ionic conductivity. Here, we studied the behavior of PAm hydrogels dialyzed in common electrolyte solutions while carrying out a systematic investigation of how specific ions influence the ionic complexes of tough PAm hydrogels. In the second section, we have utilized the PAm hydrogels as self-adhesive, transparent and stretchable electrodes to build a thermochromic liquid crystal-based skin-like wearable electronic device that can carry out dual detection of tactile and temperature sensation simultaneously. This device provides a facile and an inexpensive platform for smart electronic skins for biomedical and internet of things applications.