Continuous Conjugated Polymer Network in Elastomer Matrix Arising from Solution‐State Aggregation and Film‐Forming Dynamics Favoring Mechanical and Electrical Properties

Abstract The continuous conjugated polymer network structure in an elastomer matrix is significant for carrier transport. However, high‐mobility conjugated polymers tend to form island‐like phase separation. Here, a strategy is proposed to achieve a continuous conjugated polymer network structure via weakening the intermolecular interaction between the conjugated polymer chains and fast aggregation between conjugated polymer backbones during the film‐forming process. This is enabled by hot spin‐coating poly(2,5‐bis(4‐hexyldodecyl)‐2,5‐dihydro‐3,6‐di‐2‐thienyl‐pyrrolo[3,4‐c]pyrrole‐1,4‐dione‐alt‐thiophene) (PDPPT3) and polystyrene‐ block ‐poly(ethylene‐ran‐butylene)‐ block ‐polystyrene (SEBS) blend hot solution at 130 °C. In the solution state, PDPPT3 is observed to form small aggregates at 130 °C due to the decreased intermolecular interaction. In the film‐forming process, these small aggregates grow rapidly and form a continuous network due to the enhanced polymer chain motion. In the meantime, the large‐scale phase separation is suppressed by the short film formation time. Eventually, a sandwich‐like vertical phase separation is generated, comprising a PDPPT3‐enriched continuous network at both the top and bottom surfaces. Under strain, this small‐scale phase separation PDPPT3 network can rotate freely and maintain sufficient connections for carrier transport. Finally, the optimized films exhibit 177% fracture strain and high average mobility of 0.99 cm 2 V −1 s −1 over 500 stretch‐release cycles. This study offers a valuable approach for controlling morphology in blend systems.