Proton exchange membranes for a direct methanol fuel cell were prepared by blending poly(vinylidene fluoride) [PVDF] with sulfonated poly(etheretherketone) [SPEEK]. The effects of PVDF content on methanol permeability in the blend membranes were investigated by using a diffusion cell and gas chromatography technique. The thermal resistance and proton conductivity of the membranes were also determined by using a thermal gravimetric analysis (TGA) and an impedance analysis technique, respectively. It was found that methanol permeability in the blend membranes decreased with PVDF content at the expense of proton conductivity. The methanol permeability values of the blend membranes are much lower than that of Nafion 115, whereas proton conductivities of the membranes are comparable to that of Nafion. The thermal stability of these blend membranes are above 2508C which is sufficiently high for use in DMFC.

Sulfonated poly(vinyl alcohol) (PVA) for use as a proton conductive membrane in a direct methanol fuel cell (DMFC) was prepared by reacting the PVA with sulfoacetic acid and poly(acrylic acid). The effects of the amount of sulfoacetic acid and poly(acrylic acid) on proton conductivity, methanol permeability, water uptake, and ion exchange capacity (IEC) of the sulfonated PVA membranes were investigated by using impedance analysis, gas chromatography, gravimetric analysis, and titration techniques, respectively. The water uptake of the membranes decreased with the amount of the sulfoacetic acid and the amount of poly(acrylic acid) used. The proton conductivity and the IEC values of the membranes initially increased and then decreased with the amount of the sulfoacetic acid. The methanol permeability of the sulfonated PVA membranes decreased continuously with the amount of the sulfoacetic acid.

Electrolyte nanocomposite membranes for proton exchange membrane fuel cells and direct methanol fuel cells were prepared by carrying out a sulfonation of poly(vinyl alcohol) with sulfosuccinic acid and adding a type of organically modified montmorillonite (layered silicate nanoclay) commercially known as Cloisite 93A. The effects of the different concentrations (0, 2, 4, 6, 8 wt. %) of the organoclay in the membranes on water uptake, ion exchange capacity (IEC), proton conductivity, and methanol permeability were measured, respectively, via gravimetry, titration, impedance analysis, and gas chromatography techniques. The IEC values remained constant for all concentrations. Water uptakes and proton conductivities of the nanocomposite membranes changed with the clay content in a nonlinear fashion. While all the nanocomposite membranes had lower methanol permeability than Nafion115, the 6% concentration of Cloisite 93A in sulfonated poly(vinyl alcohol) membrane displayed the greatest proton conductivity to methanol permeability ratio.

The research presented details chemical modifications of poly(vinyl chloride) (PVC) and its derivative, dehydrochlorinated PVC (DH-PVC) through the use of two grafting techniques, namely a normal fullerenation, using AIBN (2,2 0 -Azoisobutyronitrile), and the atom transfer radical addition (ATRA). The products were characterized and the presence of new FTIR peaks at 528 and 577 cm 21 along with new 1 H-NMR signal at 3.9 ppm, suggested that fullerenes has been grafted to the polymer molecules. Percentage of C 60 in the fullerene grated products determined by UV/Visible spectroscopy initially increased with the amount of fullerene used to a maximum value (5.66 % wt) before decreasing again. It was also determined that the C 60 content of the fullerene grafted PVC product prepared by using ATRA, was notably greater than that obtained using the normal fullerenation approach, regardless of the amount of C 60 used. When the dehydrochlorinated PVC was used as the starting polymer for fullerenation, the fullerene grafted DH-PVC using ATRA, was markedly insoluble in many common solvents (THF and dichlorobenzene). This was not the cases for the fullerene grafted DHPVC prepared via an AIBN based fullerenation. Furthermore, the electrical conductivity values of the modified PVC products determined by using a four-point probe method were found to increase linearly with the amount of C 60 present. Overall our data suggest that the suitable and efficient techniques for grafting C 60 onto PVC and DHPVC chains are ATRA and AIBN-based fullerenation, respectively.

Sulfonated graphene oxide (sGO) was used as a filler to enhance performance of sulfonated poly(ether ether ketone)(sPEEK) membrane. The sGO was firstly prepared by treating graphene oxides (GO) with sulfanilic acid at 70 °C for 20 h. The sGO was characterized by FTIR and XPS techniques. Composite membranes of various amount of sGO were fabricated via solution casting method. The properties of composite membranes were investigated by measuring ion exchange capacity (IEC), water uptake, ion conductivity and vanadium ion permeability. From the results, it was found that the IEC and water uptake of the membranes increased after adding the sGO. Ion conductivity of the sPEEK membrane also increased from 8.94*10-3 Scm-1 to 10.55*10-3 Scm-1. Moreover, permeability of vanadyl sulfate (VOSO4) through the composite membranes were decreased. These composite membranes exhibit great potential for vanadium redox flow batteries application.