Hydrophobic Effect on Alkaline Stability of Graft Chains in Ammonium‐type Anion Exchange Membranes Prepared by Radiation‐Induced Graft Polymerization

Abstract

Vinylbenzyltrimethylammonium hydroxide (VBA) and styrene (St) cografted poly(ethylene-co-tetrafluoroethylene) anion exchange membranes (VBA/St-AEM) were prepared by the radiation-induced graft polymerization of chloromethylstyrene and St and sequential quaternization and anion exchange reactions. Increasing the St content in the grafts to 63 % resulted in a gradual 21 % and 34 % decrease in the conductivity and water uptake, respectively, compared to those in the VBA-homo-grafted AEM. AEMs with a higher St content (81 %) showed a 9 % and 18 % higher conductivity and water uptake, respectively. Small-angle neutron scattering showed that the sudden growth of "water puddles" consisting of waterrich nano-domains dispersed randomly in phase-separated hydrophilic ion channels enhanced the conductivity and water uptake. In the alkaline durability test of VBA/St-AEM in 1 M potassium hydroxide at 80°C for 720 h, the loss of the conductivity was suppressed from 43 % to 8 %, when the St contents in the grafts were increased from 0 % to 63 %.

Aryl ether-free polymer electrolytes for electrochemical and energy devices

“…The RG method also requires access to highenergy radiation facilities and may only be amenable to batch processes on scale-up, rather than use with continuous processes such as roll-to-roll. For improvements and tailoring of RG-AEMs for specific use in AEMWEs, the following adaptations should be researched: (1) covalent and ionic crosslinking to reduce swelling in water to yield more dimensional stability; 373,443,444 (2) incorporation of co-monomers to improve stability towards ROD including introducing antioxidants 442,445 or MAN (the latter to reduce gas crossover); 446 (3) incorporation of co-monomers such as styrene to modify nanomorphologies to alter conduction and water transport properties as well as to tailor mechanical properties; 447 (4) incorporation of aliphatic sidechains (non-aromatic) on the grafted component.…”

Composite Proton-Conducting Membrane with Enhanced Phosphoric Acid Doping of Basic Films Radiochemically Grafted with Binary Vinyl Heterocyclic Monomer Mixtures

“…This technique provides a compelling way to prepare ionic membranes by integrating many vinyl monomers with polymeric sheets/films as starting substrates to acquire functional groups imparting desired properties. Thus, RIG has been widely utilized to prepare a variety of polymer electrolyte membranes for various types of electrochemical storage including vanadium redox flow batteries and electrochemical conversion devices, such as PEMFC [ 22 , 23 , 24 , 25 , 26 , 27 , 28 ]. Of particular interest, PCMs for HT-PEMFC were pursued several years ago, and few alternative acid/base membranes were prepared by RIG of 4-vinylpyridine (4-VP) or 1-vinylimdazole (1-VIm) onto partially fluorinated polymers such as poly(vinylidene fluoride) (PVDF) and poly(ethylene- co -tetrafluoroethylene) (ETFE) films followed by PA acid doping under controlled conditions.…”

Membranas de troca aniônica baseadas em polietileno aplicadas como eletrólito polimérico alcalino em dispositivos eletroquímicos

“…Uma variedade de materiais poliméricos tem sido sugerida para a fabricação de AEMs [8][9][10], no entanto, o principal desafio é aliar características como condutividade, durabilidade, estabilidade e baixo custo dos seus componentes. Tais propriedades dependem tanto da natureza da matriz polimérica quanto dos grupos funcionais [11], bem como das etapas de processamento.…”