Nanocomposites and Nanomaterials

Proton conductive membranes for DMFC
Zhyhailo M.M.1, Demchyna O.I.1, Yevchuk I.Yu.1, Davydiuk N.M.1
1 Department of Physico-Chemistry of Fossil Fuels, L.M. Lytvynenko Institute of Physico-Organic Chemistry and Coal Chemistry of the NAS of Ukraine. 
Naukova Str., 3a, Lviv-79060, Ukraine. 
E-mail: demchynaoksana@ukr.net

Direct methanol fuel cells (DMFCs) have recently gained much attention as perspective energy sources [1]. However, they have some shortcomings such as methanol crossover through membrane. Perfluorosulfonate ionomer membranes Nafion are currently used as PEMs in DMFCs. They have a serious methanol crossover problem. 
We propose hybrid organic/inorganic cross-linked materials based on monomers acrylonitrile (AN), acrylic acid (AA), ethyleneglycole dimethacrylate (EGDMA), sodium styrene sulfonate (SSS) and sol-gel system of tetraethoxysilane (TEOS) and 3-methacyloxypropyltrimethoxysilane (MAPTMS) synthesized by UV-polymerization and sol-gel process in situ. Monomer ratio in feed composition was as follows: AN:AA:EGDMA:SSS = 44:20:20:14 wt. %. The amount of the added SGS was 3-5 wt. %. 
The measured by impedance spectrometry proton conductivities of the prepared membranes at ambient temperature are high – 2.58 - 2.85 mSm/cm. The values of methanol uptake of the cross-linked composite membranes are within 9.5 - 8.3 wt. %, what is much lower than that of Nafion membrane. 
Hence, the introduction of sol-gel precursor into monomer mixture leads to formation organic/inorganic network and greatly reduces methanol permeability of the membrane. 
The proposed poly(AN-co-AA-co-EGDMA-co-SSS-co-MAPTMS)/SiO2 may be considered as a potential candidate for DMFC application.

1.	Kim D. J., Jo M. J., Nam S. Y. A review of polymer-nanocomposite electrolyte membranes for fuel cell application // J Ind Eng Chem.-2015.-21.-P. 36-52.