Current fuel cell polymer exchange membranes suffer from a limited operating temperature range of up to 80°C, high humidity requirements, and expensive and hazardous synthesis. Poly (arylene-ether-sulfone) (PAES) offers a low cost, mild synthesis alternative to current fuel cell membranes with better thermal properties and similar ion transfer properties. While PAES is a competitive alternative, it requires higher degrees of sulfonation, for the same ion exchange capacity as leading fuel cell membranes. However, high sulfonation levels lead to an increased absorption of water and limited mechanical properties. This research is focused on using cyanuric chloride derivatives incorporated into the PAES structure for post modification of polymer properties to stabilize the mechanical deficiencies caused by high sulfonation requirements. 2,4-dichloro-6-methoxy-triazine (DCMT) was synthesized and directly incorporated into a PAES backbone via direct polymerization with 4,4’-dichlorodiphenyl sulfone, sulfonated 4,4’-dichlorodiphenyl sulfone, and 4,4’-biphenol under nucleophilic aromatic substitution conditions and confirmed by C13 NMR. While thermally stable up to 488°C, these polymers exhibited high levels of crystallinity in polar aprotic solvents, rendering it unsuitable for membrane applications. Processing methods are being explored to reduce crystallinity in this polymer. Meanwhile, focus will also be given to creating copolymers of 2,4-di(4,4'-(propane-2,2-diyl) biphenol-6-methoxy-1,3,5-triazine and dichlorodiphenyl sulfone. Mechanically stable membranes will be acidified and tested for proton conductivity. Steps are underway to convert the methoxy group of DCMT polymers into a more reactive hydroxy group and restore functionality to the PAES chain. Additionally, other cyanuric chloride derivatives will be investigated for use as post polymerization modifiable units.

Post synthesis modifiable polymers via cyanuric chloride derivatives

256th National Meeting (2018)

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