Nanophase-Separated Block-co-Polymers Based on Phosphonated Pentafluorostyrene and Octylstyrene for Proton-Exchange Membranes

Nanophase separation into hydrophobic and hydrophilic domains in commercial perfluorosulfonic acid polymers promotes high conductivity by forming proton-conductive channels within a matrix. To transfer this beneficial phase to phosphonic functionalized ionomers, we combine phosphonated polypentafluorostyrene flexible polyoctylstyrene di-block-co-polymer. We introduce stepwise approach, including mesophase simulations, synthesis, spectroscopic imaging. After the required block lengths were calculated, controlled radical polymerization led narrowly distributed block-co-polymer. The respective block-co-polymer membrane outperforms pentafluorostyrene blend concerning water uptake. Stained cross-sections revealed bicontinuous nanophase 13 25 nm range transmission electron microscopy. ion-conducting polymer assembled an isotropic, three-dimensional gyroidal network across membrane. Our approach is transferable toward other systems featuring different monomers or functional groups. Applying proposed principles allows for prediction of structure-related while reducing amount synthesis work.