This submission was created using the RSC Article Template (DO NOT DELETE THIS TEXT) (LINE INCLUDED FOR SPACING ONLY -DO NOT DELETE THIS TEXT)Vinylbenzyl chloride was grafted onto PVDF and FEP polymer films using the radiation-grafting methodology. Subsequent reaction with trimethylamine and ion-exchange with potassium hydroxide yields alkaline anion-exchange membranes that are capable of conducting hydroxide ions; such membranes may be suitable for use in low temperature direct methanol fuel cells for portable devices. The PVDF based materials underwent an undesirable degradation and were found to be less suitable for this class of membrane. FEPbased materials exhibited superior structural stability, conductivities up to 0.02 S cm -1 at room temperature, and good retention of ionexchange capacities when treated in water at 60°C.

Vinylbenzyl chloride (VBC) has been radiation grafted onto both PVDF and FEP fluoropolymer films. Subsequent amination with trimethylamine and ion-exchange to give the hydroxide ion forms yield anion-exchange membranes (AEMs) suitable for use in low temperature direct methanol fuel cells (DMFCs) for portable applications. The polymeric backbone of the PVDF-based materials degrades on alkaline treatment; significantly, this is not the case for the FEPbased materials.Two obstacles inhibiting application of DMFCs are (i) the relatively low activity and high costs of methanol electrooxidation catalysts and (ii) methanol crossover through current generation proton-exchange membranes (PEMs). 1Liquid alkaline fuel cells (AFCs) have been developed to a significant level; a principle reason for this is that the catalysts generally perform better in alkaline conditions and at lower loadings, and a wider range of catalyst may be used.2 McLean et al. observed in a recent review on AFCs that there is a great potential in the production of a polymer alkaline membrane fuel cell. 3 There has recently been growing interest in the literature on using AEMs in fuel cells, 4 an example being recent work by Agel et al. on polyethylene oxide membranes containing dissolved potassium hydroxide. The stability of a commercially available AEM containing benzyltrimethyl ammonium groups radiation-grafted onto PTFE membranes in aqueous sodium hydroxide solution (6 mol dm -3 ) was good up to temperatures between 50 -60°C. 5DMFCs operating at ambient conditions have been identified as ideal for replacing batteries for portable applications (laptops, cellular phones, man-portable power packs) due to the ever increasing power demands (especially with the imminent introduction of mobile broadband communications) that will surpass levels projected for secondary battery technology. 6DMFCs are amenable to portable applications due to the good power density of the dense and easily replenished liquid fuel (methanol). Under alkaline conditions the fuel cell reactions for the anode (1) and the cathode (2) are:Product water is formed at the anode, in contrast to a cell containing a PEM. The use of an alkaline AEM could resolve the problem of methanol crossover from the anode to the cathode as the electro-osmotic water transport occurs in the opposite direction; the use of cheaper catalysts would also be feasible. Polymer alkaline exchange membranes have been reported to function in the presence of carbonate species and could yield a solution to the problem of carbonate build-up in liquid-based AFCs. 3In fuel cell membrane research the effort has been concentrated on PEMs, 7 with the focus being the development of cheaper alternatives to the industry standard Nafion ® produced by Dupont. A large proportion of this effort has examined styrene radiation-grafting onto partially fluorinated films 8,9 such as poly(vinylidene fluoride) (PVDF, -[CH 2 CF 2 ] n -) and fully fluorinated films 9 such as poly(tetrafluoroethene-cohexafluoropropylene) (FEP, -[CF 2 CF 2 ...

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