Electrostatic Tailoring\nof Freestanding Polymeric\nFilms for Multifunctional Thermoelectrics, Hydrogels, and Actuators

Organic conducting polymer poly(3,4-ethylene­dioxythiophene):poly(4-styrene­sulfonate)\n(PEDOT:PSS) has garnered enormous attention in organic electronics\ndue to its low-cost solution processability, highly tunable conductivity,\nsuperior mechanical flexibility, and good biocompatibility together\nwith excellent atmospheric stability. Nevertheless, limited electrical\nproperties and unfavorable water instability of pristine PEDOT:PSS\nfilm impede its further implementation in a broad spectrum of practical\napplications. In this work, the successful tailoring of the intrinsic\nelectrostatic interaction within PEDOT:PSS and consequent optimized\nelectrical properties are enabled by a simple yet effective ionic\nsalt post-treatment strategy. The choice of zinc di[bis(trifluoro­methylsulfonyl)­imide]\n(Zn(TFSI)<sub>2</sub>) not only endows the post-treated PEDOT:PSS\nfilm with high electrical properties but also other compelling characteristics,\nincluding superior water stability, excellent mechanical flexibility,\nand fast humidity responsiveness. Multidimensional characterizations\nare conducted to gain in-depth insights into the mechanisms underlying\nsuch improved performance, ranging from intermolecular interactions,\npolymer conformations, and doping levels to microstructural characteristics.\nBenefiting from these versatile properties, the as-prepared freestanding\nZn(TFSI)<sub>2</sub>-post-treated PEDOT:PSS films can serve as promising\ncandidates for high-performance polymeric materials integrated into\nmultifunctional flexible electronics, including thermoelectric power\ngenerators, conductive hydrogels, and humidity-responsive actuators.\nThis study demonstrates a facile methodology for the exploration of\nmultifunctional conducting polymers, whose implications can extend\nacross a wide range of next-generation wearable devices, bioelectronics,\nand soft robotics.