(469g) Side-Chain Engineering of Mixed Conducting Polymers Using Coarse-Grained Molecular Dynamics

Organic mixed ion-electron conducting (OMIEC) polymers exhibit transport of both electrons and ions. This unique functionality underpins many emerging applications including, biosensors, organic electrochemical transistors, neurocomputing devices, and batteries. OMIEC design is incipient, and the few materials that have been synthesized have been based on electron conducting units and ion conducting units from adjacent applications in organic semiconductors and polymer electrolytes, respectively. Although this modular approach has produced materials exhibiting mixed transport, further progress is frustrated by incomplete knowledge of how ionic and electronic transport are coupled in these materials and the absence of design rules specific to OMIECs. In this presentation, we will present a simulation case study on the effect of OMIEC side-chain identity on electrolyte penetration and morphology. A flexible coarse-grained model recently developed by our group enables variation of backbone anisotropy, persistence length, side-chain density, hydrophilicity, and patterning. This model is used to systematically interrogate how these polymer properties affect electronic-ionic coupling and charge transport. We observe that the side-chain identity qualitatively impacts the features of charge transport, with observed behaviors ranging from facile macroscopic conduction through a percolating polymer network to severe charge trapping in isolated polymer aggregates. Mechanistic investigations reveal that the side-chains impact charge transport through two distinct mechanisms. First, by mediating the OMIEC morphological rearrangement that accompanies electrolyte percolation, and second, by controlling ion-polymer distributions within the electrolyte swelled OMIEC. This represents the first systematic investigation of how side-chain attributes affect the molecular details of charge transport in OMIECs and suggest near-term opportunities for side-chain engineering.