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In this work, the functionalization of polystyrene-bpoly(butadiene)-b-polystyrene triblock copolymer (SBS) with vinylbenzyl chloride and benzoyl peroxide (BPO) or a,a 0 -azobis-isobutyronitrile (AIBN) as free radical initiators was reported. The functionalization degree (FD), calculated by 1 H NMR spectroscopy and confirmed by elemental analysis, was highly tunable (from 4 to 10 mol %) and positively correlated to the starting percentage of radical initiator. More specifically, at the same initiator molar percentage grafting efficiency is higher using BPO rather than AIBN. Quaternization reaction of the grafted benzyl chloride groups with the bifunctional tertiary amine 1,4-diazabicyclo[2.2.2]octane (Dabco) led to a chemically and thermally stable homogeneous anion-exchange membrane. Electrochemical parameters were evaluated for Dabco-quaternized grafted copolymers having different FDs, and compared with a commercial Tokuyama benchmark membrane. Experimental data showed a positive correlation between FD and both water swelling and ionic conductivity. Best trade-off between ionic conductivity and water swelling was found for membrane having FD 9.1 mol %, which conductivity is comparable with the Tokuyama benchmark one and water uptake is only slightly higher. The results are discussed based on the molecular parameters with particular reference to ionic content and distribution. V C 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 49: [3437][3438][3439][3440][3441][3442][3443][3444][3445][3446][3447] 2011

H2/O2 AMFCs enable the use of Platinum Group Metal (PGM) free Membrane Electrode Assemblies (MEAs), especially for the Oxygen Reduction Reaction (ORR). A promising catalysts for the ORR (Acta's "K14"), has been developed and tested using Rotating Disk Electrode (RDE) analysis, showing promising performance. In this paper we characterize current Anion-Exchange Membranes (AMs), show the fuel cell activity of AM-based MEAs prepared with K14 ORR catalyst, and compare their performance with the kinetic and ohmic limits projected from the membrane and catalyst properties. The data and projections show promising results for this technology.

In this work, different amines (bifunctional, as diazabicyclo[2.2.2]octane (Dabco) and monofunctional, as N-methylimidazole or trimethylamine) were utilized for the amination of benzyl chloride-grafted polystyrene-b- poly(butadiene)-b-polystyrene triblock copolymers (SBS-g- VBC). The use of Dabco solutions in mixture with variable amounts of monoamine or at different concentration allowed to modulate the degree of crosslinking of the SBS-based membranes and their electrochemical parameters. More specifically, tuning Dabco concentration permitted the reduction of water uptake without significantly affecting ionic conductivit

In this work, a commercial SBS was functionalized with the 2,2,6,6-tetramethylpiperidin-N-oxyl stable radical (TEMPO) via free-radical activation initiated with benzoyl peroxide (BPO). The obtained macroinitiator was used to graft both vinylbenzyl chloride (VBC) and styrene/VBC random copolymer chains from SBS to create g-VBC-x and g-VBC-x-co-Sty-z graft copolymers, respectively. The controlled nature of the polymerization as well as the use of a solvent allowed us to reduce the extent of the formation of the unwanted, non-grafted (co)polymer, thereby facilitating the graft copolymer’s purification. The obtained graft copolymers were used to prepare films via solution casting using chloroform. The –CH2Cl functional groups of the VBC grafts were then quantitatively converted to –CH2(CH3)3N+ quaternary ammonium groups via reaction with trimethylamine directly on the films, and the films, therefore, were investigated as anion exchange membranes (AEMs) for potential application in a water electrolyzer (WE). The membranes were extensively characterized to assess their thermal, mechanical, and ex situ electrochemical properties. They generally presented ionic conductivity comparable to or higher than that of a commercial benchmark as well as higher water uptake and hydrogen permeability. Interestingly, the styrene/VBC-grafted copolymer was found to be more mechanically resistant than the corresponding graft copolymer not containing the styrene component. For this reason, the copolymer g-VBC-5-co-Sty-16-Q with the best balance of mechanical, water uptake, and electrochemical properties was selected for a single-cell test in an AEM-WE.