Proton conducting membranes, aromatic polymers

Sgreccia, E., Chailan, J.F., Khadhraoui, M., Di Vona, M.L., Knautha, R, Mechanical properties of proton-conducting sulfonated aromatic polymer membranes Stress-strain tests and dynamical analysis, J. Power Sources, 2010, 195, 7770-7775. 

Aromatic condensing polymers with fragments of benzimidazole or quinoxaline as base in electrolytic proton-conducting membranes 02UK862. 

Proton-conducting ionomers for polymer electrolyte membrane fuel cell (PEMFC) is one area in which extensive research is ongoing to modify aromatic main chain polymers to tailor their properties as proton conductors [1-... 

Different strategies have been described in the hterature for obtaining cross-Unked aromatic proton conductive membranes based on polyphos-phazene [108], polysulfone [109], and polymer blends [110]. However, as mentioned by Kerres in a review article [111], ionically cross-linked membranes are not suitable for high-temperature apphcations because of excessive water membrane swelling. Accordingly, particular interest has been devoted... 

Abstract Chemical structure, polymer microstructme, sequence distribution, and morphology of acid-bearing polymers are important factors in the design of polymer electrolyte membranes (PEMs) for fuel cells. The roles of ion aggregation and phase separation in vinylic- and aromatic-based polymers in proton conductivity and water transport are described. The formation, dimensions, and connectivity of ionic pathways are consistently found to play an important role in determining the physicochemical properties of PEMs. For polymers that possess low water content, phase separation and ionic channel formation significantly enhance the transport of water and protons. For membranes that contain a high... 

Water uptake of the SPEEK membrane is known to increase with the increase in DS due to enhancement of the hydrophilicity when introdncing the snlfonic acid groups in the aromatic PEEK polymer. These sulfonic acid groups, in the presence of water molecules, facilitate proton transfer through the membrane, thus increasing the proton conductivity. Therefore, water uptake is a crucial characteristic of the SPEEK membrane, since it is proportional to DS and proton conductivity. However, as methanol transfer is also facilitated by the water molecules, increasing the water uptake normally increases the methanol permeability as well. 

Aromatic polymers with phosphonated sites directly linked to the main chain have also been prepared by direct polymerization (Scheme 13.2a-d). For example, phosphonated poly(l,3,4-oxadiazole)s have been prepared by direct polycondensation of l,4-dicarbo3y-2-phenyl-phosphonic acid and their dihydrazides in an ionic liquid using triphenyl phosphite as a reaction activator. " The membranes obtained from these polymers were thermally and chemically stable and possessed proton conductivities in the range between 4x10 " and 5x10 mS cm at 100% RH, which is three orders of magnitude lower than the state-of-the-art PFSA membrane Nation . 

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