The role of TEOS-TIP within a pentablock ionomer: Morphology, physical properties, and ion transport

Inorganic–organic nanocomposites were created using tetraethylorthosilicate (TEOS), titanium isopropoxide (TIP), and poly(t-butylstyrene-b-hydrogenated isoprene-b-sulfonated styrene-b-hydrogenated isoprene-b-t-butylstyrene) or pentablock copolymer (PBC). A TEOS–TIP–H₂O ternary phase diagram was generated to create homogenous sol solutions with designable condensation reactions that led to controllable materials. An inorganic TEOS–TIP network was synthesized using sol–gel chemistry within the organic PBC domain. All TEOS–TIP–PBC films exhibited higher water sorption than unmodified PBC ionomer that was attributed to a change in morphology. Proton conductivity increased up to 80% due to TEOS–TIP within the nanocomposite film. This can be attributed to ion domain redistribution and partial charge transfer from the titanate's inorganic domains to sulfonate groups that promote acid dissociation. PBC had a microphase-separated morphology that changed with increasing TIP concentration, which was observed from atomic force microscopy and small-angle X-ray scattering results. Finally, thermal gravimetric analysis revealed a decrease in degradation temperature, and dynamic mechanical analysis results demonstrated reduced polymer chain mobility caused by inorganic–organic interactions.