Microphase-Separated Thiol–Ene Conetworks from Telechelic Macromonomers with Asymmetric Molecular Weights

Phase-separated networks made from different macromonomers with disparate properties provide a platform where the molecular weight between cross-links (M c) can be varied leading to tunable mechanical and conductive properties. To form networks with bimodal M c’s, two volume fraction series, A and B, were synthesized from telechelic polystyrene (PS) and poly­(ethylene oxide) (PEO) of varying molecular weights (MW), using thiol–norbornene chemistry to tune M c. Series A consisted of 4K PEO and 12K PS, and series B consisted of 12K PEO and 5K PS. Phase separation in the network was confirmed by DSC where two distinct glass transition temperatures were observed and by SAXS where broad, weakly ordered scattering was observed. The networks were further characterized to probe how bimodal M c affects the mechanical and conductive properties of phase-separated networks. The two series demonstrated that the asymmetric MW studied herein had little effect on mechanical and lithium conductive properties while changes in these properties were primarily influenced by the volume fraction of PEO.