Block copolymers composed of styrene and different elastomeric blocks were sulfonated to high ion exchange capacities (IECs). Titanium dioxide (TiO2) nanoparticles were added to these polymers to improve their mechanical and thermal stabilities, while influencing their transport properties for direct methanol fuel cell (DMFC) applications. Materials properties as proton exchange membranes (PEMs) were analyzed using: FT‐IR, water absorption, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), IEC, methanol permeability, and proton conductivity studies. Although there was no effect of TiO2 nanoparticles on the thermal stability of the membranes, significant changes were observed in the mechanical properties of both sulfonated block copolymers studied. Water absorption increased at low TiO2 content, but was then reduced with the incorporation of more nanoparticles. To enhance the interaction between the inorganic fillers and the polymers, sulfonic and amino groups were attached to the surface of the titania nanoparticles. The effect of sulfonated nanoparticles on the properties of the materials was more significant than the effect of the amino functionalized nanoparticles on all the properties evaluated, suggesting enhanced chemical interactions with the ionic domains of the polymer membranes. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42651.

Ionic liquids (ILs) with different anions and cations were incorporated in sulfonated poly(styrene‐isobutylene‐styrene) (SIBS) to modify its chemical, morphological, and transport properties for direct methanol fuel cell (DMFC) applications. Different loadings of IL and different solvents were studied to have a better understanding of the incorporation process and the ability of the solvent to affect the interaction of the IL with the sulfonated polymer. Morphological characterization with SAXS and AFM suggested changes caused by the incorporation of the IL and by the solvent used. FT‐IR spectra showed small variations in energy related to interactions of the IL with the sulfonic groups which caused thermogravimetric stabilization of the ionic domains. Other results suggest that water has a very significant effect on the morphology, interaction with the IL, and transport properties of the membranes. Optimal concentration of IL (∼10 mol %) provides enough water to produce efficient proton conductivity (0.15 S/cm) and minimal methanol permeability (0.8 × 10−6 cm2/s). © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2017, 134, 44900.

Graphene oxide (GO) and its sulfonated analog (sGO) have been incorporated into sulfonated poly(styrene‐isobutylene‐styrene) (SO3H SIBS) in order to enhance its water retention and proton conductivity, while aiming to block permeant passage through the material. The polymer nanocomposite membranes (PNMs) were tested for two applications: direct methanol fuel cell and chemical and biological protective clothing. The transport properties of the membranes were determined as a function of SIBS sulfonation level (i.e., 37, 61, and 88 mol%), filler type (i.e., GO and sGO) and filler loading (i.e., 1, 3, 5, and 10 wt%). Fourier transform infrared spectroscopy (FTIR) and thermogravimetric analysis (TGA) confirmed the functionalization and incorporation of the fillers into SO3H SIBS. No significant changes were observed in the thermal stability or FTIR spectra of the PNMs after addition of the fillers. Dissimilar behaviors were observed for the ion exchange capacity, water absorption capabilities and transport properties of the membranes after incorporation of the fillers. Atomic force microscopy (AFM) phase images and Fenton's test results indicate that the oxidative stability of the PNMs is associated to the interconnectivity between the hydrophilic domains of the fillers and SO3H SIBS. The PNMs presented low permeability and high proton conductivity and thus, functioned adequately for both applications. POLYM. ENG. SCI., 59:E455–E467, 2019. © 2018 Society of Plastics Engineers