Facile synthesis and properties of poly(ether ketone cardo)s bearing heterocycle groups for high temperature polymer electrolyte membrane fuel cells

Novel high temperature polymer electrolyte membranes (HT-PEMs) are fabricated from commercial and low-cost poly(ether ketone cardo) (PEK-Cardo). Rather than normal chloromethylation and quaternization procedure to introduce basic groups into poly(arylene ether)s, three different long side-chain basic groups are grafted into PEK-Cardo through a facile one-step lactamization between the cardo phenolphthalein type moiety in PEK-Cardo and amino compounds (i.e. 1-(3-aminopropyl) imidazole (APIm), 1-(3-aminopropyl) pyrrolidin-2-one (APy) and 3-(dimethylamino)-1-propylamine). The obtained lactamized PEK-Cardo membranes exhibit excellent phosphoric acid doping capability and the physicochemical properties are optimized by adjusting the chemical structure and grafting degree of side-chain basic groups. Fuel cell results demonstrate a big potential for HT-PEMFC applications. Thus, this proposal provides a new, straightforward and low-cost method to prepare high-performance HT-PEMs.