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Towards Sustainable Polymeric Materials for Fuel Cells: Focus on Hydrocarbon Membranes and on the Development of Alkaline Exchange Membranes Shulamith.

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Presentation on theme: "Towards Sustainable Polymeric Materials for Fuel Cells: Focus on Hydrocarbon Membranes and on the Development of Alkaline Exchange Membranes Shulamith."— Presentation transcript:

1 Towards Sustainable Polymeric Materials for Fuel Cells: Focus on Hydrocarbon Membranes and on the Development of Alkaline Exchange Membranes Shulamith Schlick, University of Detroit Mercy, DMR 0964827 1. Danilczuk, M.; Schlick, S.; Coms, F.D. Macromolecules dx.doi.org/10.1021/ma401188u. 2. Lancucki, L.; Schlick, S.; Danilczuk, M.; Coms, F.D.; Kruczala, K. Polym. Degrad. Stab. 2013, 98, 3-11. 3. Manuscript in preparation. General Comments. During this period we have moved in two directions: To replace the fluorinated membrane by the less costly poly(arylene ether)-based sulfonated polymers, Part (A), and to develop alkaline exchange membranes (AEMs) that have the ability to operate with non-noble metal catalysts such as silver or nickel instead of Pt, Part (B). (A) We performed experiments in a fuel cell (FC) inserted in the resonator of the electron spin resonance (ESR) spectrometer, which allowed separate monitoring of radical formation at anode and cathode sides. 1 The in situ FC was operated with sulfonated poly(ether ether ketone) (SPEEK) as the membrane. The formation of radicals was monitored by spin trapping ESR, with 5,5-Dimethyl-1-pyrroline N-oxide (DMPO) as the spin trap. The results showed that these hydrocarbon membranes are more stable in a FC compared to ex situ experiments (Fenton test). Experiments with Sparmax were also published. 2 Figure 1. The detection of DMPO adducts at the anode. The major adducts were DMPO/OOH and DMPO/H. The generation of adducts was explained by crossover of oxygen and hydrogen and by the generation of hydrogen atoms at the Pt catalyst, as described in detail in our 2012 ACS Macro Letters paper. (B) We determined the chemical stability of alkaline exchange membranes (AEMs) prepared from the perfluorinated 3M precursor having terminal sulfonyl fluoride, –SO 2 F, groups in the side chains of the backbone. The AEMs were synthesized by covalent attachment of trimethyl ammonium (TMA), 1,4- dimethylpiperazinium (DMP), and quaternized 1,4-diaza bicyclo[2.2.2]octane (DABCO) cations to the –SO 2 F groups. 3 The chemical stability of AEMs was determined from FTIR spectra as a function of exposure time to KOH; the spectra indicated the disappearance of the C-H bands of the amines. However, the high conductivity, together with the detection of an HO – band at 3680 cm -1, suggested that the degraded AEMs still possess properties required for performing as AEMs. We are suggesting that the HO – groups remain in the water clusters and are responsible for the high conductivity, even in “degraded” AEMs, which lost the C-H bands of the amine groups. The detection of the S-N IR band at 986 cm -1 before and, more importantly, after the disappearance of the C-H bands, pointed to the nucleophilic attack on the CH 2 and CH 3 groups by KOH. The FTIR spectra of AEMs before and after exposure to KOH, Figure 2, are shown in the Notes Page.

2 Broader Impact Activities Shulamith Schlick, University of Detroit Mercy, DMR 0964827 The Group: Postdoctorals M. Danilczuk and Admira Bosnjakovic, REU fellow David Brush, and summer 2013 high school students Michael Wallace and Andrew Mikes. Translational Research. Our collaboration with scientists and engineers from 3M, Ford Laboratories, and the Electrochemical Energy Research Lab of General Motors on the degradation and stabilization of membranes used in fuel cells is an example of the connectivity between fundamental research and applications: In-depth profiling of degradation is a new imaging method that visualizes the effect of catalyst diffusion into the membrane and the reactivity of hydrogen atoms generated in a fuel cell. And the work on alkaline exchange membranes (AEMs) has benefited from our collaboration with 3M scientists, who provided the fluorinated 3M precursor and added their ability to perform NMR experiments and to measure the conductivity of AEMs before and after exposure to KOH. Materials.The SPEEK membrane electrode assembly (MEA) was provided by our collaborators at the General Motors Global Fuel Cell Activities, in Pontiac, Michigan. Presentations.The PI and postdocs have presented our work at Fluoropolymer 2012 in Las Vegas, ACS New Orleans 2013 and Asilomar Conference Center 2013, see details in Notes Page. International Collaborations. PI Schlick has continued the collaboration with K. Kruczala and L. Lancucki (Jagiellonian University, Krakow), on the study of SParmax (Lancucki, L.; Schlick, S.; Danilczuk, M.; Coms, F.D.; Kruczala, K. Sulfonated Poly(benzoyl paraphenylene) as a Membrane for PEM FC: Thermal and Chemical Stability, Polym. Degrad. Stab. 2013, 98, 3-11). Outreach Activities. The college of Engineering and Science at UDM has initiated an outreach program with The University of Detroit High School, which involves research experience for junior HS students in the laboratories of UDM faculty. Three students selected to spend time in the Chemistry Department and of these two have chosen the PI’s lab. On 16 July our group made brief presentation to the guest students about our research, and about fuel cell work in particular. The high school students will present their work in the lab at the end of their program.


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