A Cellulose Ionogel with Rubber-Like Stretchability for Low-Grade Heat Harvesting.

Achieving rubber-like stretchability in cellulose ionogels presents a substantial challenge due to the intrinsically extended chain configuration of cellulose. Inspired by the molecular configuration of natural rubber, we address this challenge by using cyanoethyl as a substitute for 1.5 hydroxyl on the D-glucose unit of cellulose. This strategy innovatively triggers the transformation of cellulose molecules into a coiled chain configuration, facilitating the creation of an ultra-stretchable ionogel free from any petrochemical polymers. The resultant ionogel demonstrates mechanical ductility comparable to that of a rubber band, achieving an elongation strain of nearly 1,000% while maintaining a tensile strength of up to 1.8 MPa and exhibiting a biomodulus akin to that of human skin, recorded at 63 kPa. Additionally, this stretchable ionogel presents skin-like self-healing behavior, favorable biocompatibility, and noteworthy thermoelectric properties, highlighted by a Seebeck coefficient of approximately 68 mV K^-1. This study delineates a feasible molecular approach for developing stretchable ionogels from biomass resources, potentially revolutionizing self-powered stretchable electronics for integration with human tissues and skin.