Field of Expertise: Advanced Material Science
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Field of Expertise: Advanced Material Science | |
Deposition and characterization of proton conductive polymers Being able to easily synthetize electrolytes to serve as proton exchange membranes (PEM) in fuel cells with proton conductivities comparable to the actual benchmark, Nafion® is of high technological interest. In a first approach we tried to reproduce the domains of this commercial membrane by making proton conductive polymers out of 1H, 1H, 2H, 2H,-perfluorodecyl acrylate (PFDA) and methacrylic acid (MAA). A detailed X-ray based investigation of the copolymers structure was performed in order to make a throughout comparison with the microstructure of Nafion. The second approach was to synthesize this membrane out of pure hydrocarbons using methacrylic acid (MAA) and Divinylbenzene (DVB) as crosslinker, to prevent the hydrophilic MAA from dissolving in water. Proton conductivity measurements were carried out by impedance spectroscopy. The used method of synthesis, initiated Chemical Vapor Deposition (iCVD), allowed to tune the chemical composition of the copolymer in terms of ratio between ionic groups (MAA) and hydrophobic species (PFDA) and the crosslinker (MAA), respectively. While the PFDA homopolymer crystallizes in a bilayered Smectic B phase, it was shown that MAA-PFDA copolymers are crystallizing in a bilayered Smectic A phase. It was observed that the net plane distance of this bilayer structures was increased by the MAA. To explain this behavior a hypothetical model for the MAA-PFDA copolymer structure was concluded. |