Tunable Networks from Thiolene Chemistry for Lithium Ion Conduction.

End-functionalized poly(ethylene glycol) (PEG) and polydimethylsiloxane (PDMS) were cross-linked by a thiolene reaction with a tetra-functional thiol to create robust, tunable networks. These networks were loaded with increasing amounts of lithium bis(trifluoromethane sulfonyl imide) (LiTFSI), and their ion conductivity was measured. A wide range of salt loading was achieved, allowing the investigation of both salt-in-polymer and polymer-in-salt regimes. Thermal, mechanical, and ion conductivity properties of LiTFSI-loaded PEG and PEG-PDMS networks were measured. Even at high salt loadings, both networks maintained rubber-like characteristics, which were stable over a range of temperatures (30-90 °C). The PEG network with the highest salt loading showed the greatest ion conductivity, 6.7 × 10 S cm at 30 °C, as measured by impedance spectroscopy. This system provides a route to optimize lithium ion conduction and mechanical properties.