Dynamic bonds transform ion transport mechanisms in polymeric covalent adaptable networks

This study unravels the mechanisms by which dynamic covalent bonds facilitate ion transport in poly(ethylene oxide)-based covalent adaptable networks (CANs), designed for solid polymer electrolytes. Our findings reveal how CANs differ fundamentally from traditional static PEO networks in their ion conductivity behavior. Through molecular dynamics simulations, we show that dynamic bonding creates temporary "corridors" for lithium-ion movement via reversible bond breaking and reformation, without altering the network topology. Unlike static networks, which rely on structural loosening for ion diffusion, dynamic bonding uniquely enhances ion transport by inducing local bond rearrangements that create transient structural fluctuations, increasing ion mobility up to 2.8-fold in dense networks. Importantly, these transient structural changes do not alter the overall pore distribution in the network. Instead, the dynamic reactions transform blocked pathways - previously dead-ends - into reversible gates that open and close, effectively regulating ion transport. This mechanism provides a pathway to improve ion conductivity while preserving mechanical integrity.