Fabrication of PEDOT:PSS shape memory polymer composites using vertical phase separation by surface energy

Abstract In this study, we developed a novel method to fabricate a shape memory composite film composed of a continuous PEDOT:PSS matrix and isolated epoxy islands, using an air plasma-treated polypropylene (PP) substrate. Vertical phase separation was achieved by tuning the substrate’s surface energy to lie between those of the two immiscible polymers. Air plasma treatment increased the PP substrate’s surface energy, driving PEDOT:PSS to accumulate at the film–substrate interface, forming a continuous bottom layer with dispersed epoxy islands. During thermal curing, epoxy islands enlarged due to water evaporation from the PEDOT:PSS solution and subsequent epoxy crosslinking, enhancing their integrity. The PEDOT:PSS-rich bottom layer established a conductive path, while its incorporation improved the storage modulus and reduced the glass transition temperature ( T g ) through plasticization, without compromising the shape memory behavior. The resulting composite film demonstrated excellent fixity (98.6%) and recovery (93.1%) ratios while maintaining electrical resistance during shape transitions.