Poly(bis-arylimidazoliums) possessing high hydroxide ion exchange capacity and high alkaline stability

Abstract

Solid polymer electrolyte electrochemical energy conversion devices that operate under highly alkaline conditions afford faster reaction kinetics and the deployment of inexpensive electrocatalysts compared with their acidic counterparts. The hydroxide anion exchange polymer is a key component of any solid polymer electrolyte device that operates under alkaline conditions. However, durable hydroxide-conducting polymer electrolytes in highly caustic media have proved elusive, because polymers bearing cations are inherently unstable under highly caustic conditions. Here we report a systematic investigation of novel arylimidazolium and bis-arylimidazolium compounds that lead to the rationale design of robust, sterically protected poly(arylimidazolium) hydroxide anion exchange polymers that possess a combination of high ion-exchange capacity and exceptional stability.

Ether-free polyfluorenes tethered with quinuclidinium cations as hydroxide exchange membranes

“…5,6 The vast number of studies on AEMs based on different aromatic polymer backbones, including polyethers, polysulfones, polyphenylenes, polybenzimidazoles, etc., has shown that aryl ether links are sensitive to hydrolysis under alkaline conditions, especially if this reaction is activated by nearby electron-withdrawing groups such as sulfone links. [9][10][11][12][13][14][15][16][17][18][19][20] Hence, AEMs based on ether-free aromatic backbones, such as polyphenylenes, 9,[21][22][23] poly(arylene alkylene)s [24][25][26][27][28][29][30][31][32] and sterically protected polyimidazoliums, [33][34][35][36] as well as on aliphatic backbones such as poly(diallyldialkyl ammonium) 37 and polynorbornenes, 38,39 have shown excellent alkaline stability.…”

Electrospun Ionomeric Fibers with Anion Conducting Properties

“…The nonacidic environment of AEMFCs allows the use of nonprecious metal catalysts, which intensely reduces the cost per kilowatt of power of fuel cell devices . In spite of the latest technological progress related to electrocatalysts and to the understanding of carbonation issues, one of the main remaining challenges in the AEMFCs is the availability of good, stable anion conducting membranes that enable the hydroxide anion and water conduction through the polymeric network, both as an anion exchange membrane (AEM) and as anion exchange ionomers (AEIs).…”

Partially fluorinated copolymers containing pendant piperidinium head groups as anion exchange membranes for alkaline fuel cells

“…Former typically takes place at heteroatom linkages in the backbone such as arylene ether, sulphide or sulfone groups, resulting in the cleavage of the polymer main chain and thereby lowering the membranes' mechanical properties. [17][18][19] Therefore, in order to mitigate backbone cleavage, there is a shi towards polymer backbones that are devoid of any those heteroatom linkages 20,21 for long-term alkaline stability. We previously developed such a structure; a series of novel peruoroalkyl and uorene based copolymers (QPAF4) having no heteroatom linkages in the main chain which provided robust membranes with high elasticity due to the unique combination of peruoro chain and aromatics.…”