Polymer networks with dynamic covalent cross-links act as solids but can flow at high temperatures. They have been widely explored as reprocessable and self-healing materials, but their use as solid electrolytes is limited. Here we report poly­(ethylene oxide)-based networks with varying amounts of lithium bis­(trifluoromethanesulfonyl)­imide (LiTFSI) to understand the impact of a salt on the ion transport and network dynamics. We observed that the conductivity of our dynamic networks reached a maximum of 3.5 × 10–4 S/cm at an optimal LiTFSI concentration. Rheological measurements showed that the amount of LiTFSI significantly affects the mechanical properties, as the shear modulus varies between 1 and 10 MPa and the stress relaxation by 2 orders of magnitude. Additionally, we found that these networks can efficiently dissolve back to pure monomers and heal to recover their conductivity after damage, showing the potential of dynamic networks as sustainable solid electrolytes.

Vitrimers have been investigated in the past decade for their promise as recyclable, reprocessable, and self-healing materials. In this Viewpoint, we focus on some of the key open questions that remain regarding how the molecular-scale chemistry impacts macroscopic physical chemistry. The ability to design temperature-dependent complex viscoelastic spectra with independent control of viscosity and modulus based on knowledge of the dynamic bond and polymer chemistry is first discussed. Next, the role of dynamic covalent chemistry on self-assembly is highlighted in the context of crystallization and nanophase separation. Finally, the ability of dynamic bond exchange to manipulate molecular transport and viscoelasticity is discussed in the context of various applications. Future directions leveraging dynamic covalent chemistry to provide insights regarding fundamental polymer physics as well as imparting functionality into polymers are discussed in all three of these highlighted areas.

Materials that absorb shock wave energy from blasts and high-speed impacts are critical for protection of structures, vehicles, and people. Incorporating dynamic bonds into polymers has enabled precise control over the time-dependent response and energydissipating modes, but this work has focused on much slower time scales and lower forces than those associated with shock waves. Here, we design polymers networks with dynamic covalent bonds, called vitrimers, where reversible exchange reactions provide a potential mechanism for shock wave energy dissipation. Increasing the density of dynamic bonds leads to a systematic increase in energy dissipation, measured by the drop in peak pressure of a laser-induced shock wave. An analogous permanent polymer network shows no dependence of dissipation on cross-link density. The vitrimers can absorb shock multiple times while maintaining performance, attributed to bond exchange and the intrinsic self-healing ability of the polymer. Our results are the first to demonstrate that vitrimers are an effective route to the design of energy-dissipating materials, particularly at the high frequencies and pressures associated with shock waves.

Polymers are promising materials for replacing organic liquids as electrolytes, and network architectures allow for the modulus to be tuned pseudo‐independently of conductivity. When the crosslinks are dynamic bonds, they offer the additional benefits of recyclability and self‐healing in response to damage. Dynamic network electrolytes (DNEs) comprised of precise linker lengths of 2, 3, or 4 repeat units of ethylene oxide and boronic ester junctions were prepared to investigate the roles of dense networks and bond exchange on conductivity and rheological properties. A range of salt concentrations were probed, and longer linker lengths led to consistently higher conductivities even after accounting for difference in the glass transition. In contrast, non‐monotonic trends are observed in the salt dependence of viscosity as a function of linker length. The interaction of anions from the salt with boron leads to a drop in the viscosity, and at a critical salt content the networks no longer form a percolated network. From the bulk viscosity, a Walden Plot shows a transition from superionic to subionic behavior with added salt. These structure–property relationships offer key valuable insights for designing sustainable electrolytes.

A model system of single‐ion conducting network electrolytes with acrylic backbone, ethylene oxide (EO) side chains, tethered fluorinated anions, and mobile Li cations was designed and synthesized to investigate structure–property relationships. By systematically tuning four molecular variables, one at a time, we investigated how crosslinker length, mol% of crosslinker added, Li:EO ratio and side‐chain length affect conductivity, Tg, and modulus. Ionic conductivity at 90 °C varied by two orders of magnitude (and by three orders of magnitude at room temperature) depending on the molecular details, while a 70 °C span in glass transition temperature (Tg) was observed. The range of crosslinking, which can be achieved without impacting conductivity was also elucidated, and the modulus of the electrolyte can be increased by a factor of 8, up to 2.4 MPa, without impacting ion transport. Changes in conductivity due to crosslink density and crosslinker length are fully explained in terms of Tg shifts, while comonomer length cannot be accounted for by such a shift. The best performing network exhibited 10−5 S/cm at high temperature, which is comparable to other single‐ion conductors reported in the literature, while the modulus is higher due to crosslinking. Adding 10 wt% propylene carbonate further increased this value to 10−4 S/cm. This work provides insights into the structure–property relationships of solid‐state polymer electrolytes, which retain conductivity but can potentially help suppress dendrites.