Here, we achieved a reversible sol-gel transition in conductive polymers just below physiological temperature (35 °C) through a fundamentally different approach that does not rely on covalent crosslinkers nor composite blends. The key molecular design was the synthesis of a thermoresponsive block copolymer of PSS with poly(N-isopropylacrylamide) (PSS-b-PNIPAM) that was then used as a matrix to prepare PEDOT:PSS-b-PNIPAM polyelectrolyte complexes (Fig. ).