The Effect of TiO2 Nanoparticles on the Properties of Sulfonated Block Copolymer Membrane

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 TiO2nanoparticles 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.

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