Рroton conductive polymer and hybrid polymerinorganic membranes
The aim of the work is to synthesize polymer and hybrid polymer-inorganic proton conductive membranes on the base of water soluble acrylic monomers and sol-gel precursor, and characterize their properties. Materials, used for membrane preparation -acrylonitrile (AN), acrylic acid (AA), 3-sulfopropyl acrylate potassium salt (SPAK), tetraethoxysilane (TEOS), 3-methacryloxypropyltrimethoxysilane (MAPTMS), ethyleneglycol dimethacrylate (EGDMA), 2,2-dimethoxy-2-phenylacetophenone (DMPA) and phosphoric acid (85 wt. %). Methods of investigation - impedance spectroscopy, water and methanol uptake measurement, laser interferometry, SEM. Proton conductive polymer and organic-inorganic membranes were synthesized based on acrylic monomers and silica inorganic component, derived as a result of sol-gel transformation of precursors - tetraethoxysilane (TEOS) and 3-methacryloxypropyl trimethoxysilane (MAPTMS). AA, AN and SPAK were cross-linked by irradiation with UV light at the presence of photoinitiator DMPA and cross-linker EGDMA and simultaneous hydrolytic polycondensation of sol-gel precursors. Kinetics of polymerization in situ was investigated by laser interferometry. Membranes characterization includes morphology, methanol uptake and proton conductivity at different temperatures. Morphology of the membranes investigated using SEM evidences that the material structure is homogeneous without cracks and phase separation. The membranes obtained exhibit low methanol uptake and high values of proton conductivities (3.6·10-3-9.6·10-3 Sm/cm) making them attractive for fuel cell application. Contact angle measurements allow to evaluate free surface energy of the membranes. The proposed method of UV-іnitiated polymerization in situ allows one to obtain cross-linked sulfo group containing polymer and hybrid polymer-inorganic materials, which possesse a complex of necessary properties for their use in methanol fuel cells.