Surface analysis of the proton exchange membranes prepared by pre-irradiation induced grafting of styrene/divinylbenzene into crosslinked thin PTFE membranes

Radiation-grafted membranes based on polyethylene for direct methanol fuel cells

“…This indicates that the membrane contains sulfonic acid groups. The possible presence of double bonds cannot be neglected during the styrene-grafting reaction [27]; therefore, it is possible that a side reaction took place when the membranes were sulfonated by chlorosulfonic acid. A possible side reaction is the addition reaction of the chlorosulfonic acid with the double bonds on the grafts.…”

A novel approach to prepare proton exchange membranes from fluoropolymer powder by pre-irradiation induced graft polymerization

“…For PVDF-g-PS with a 21.8% DG, the F/C ratio declines to 0.99 after incorporation of polystyrene. This change in F/C ratio is far less than obtained by radiation induced graft copolymerization of styrene onto fluorine-containing films [25][26][27], where the surface was fully covered by PS chains and F element signal almost disappeared. That is closer to value predicted from theoretical calculation, which illustrates that the DG from graft copolymerization of styrene on powder and successive film casting can achieve higher uniformity than the current applied method.…”

Performance of membrane electrode assemblies based on proton exchange membranes prepared by pre-irradiation induced grafting

“…One reason for the difference in the R ct values is the different surface morphology. As reported previously [17], the surfaces of the membranes grafted by S were covered by the PS-SA chains while on the surfaces of the membranes grafted by S/DVB they were mainly F-atoms. A similar structure of the surface of the membranes grafted by S/DVB to the ionomer dispersion provided a better compatibility with the ionomer dispersion coated electrodes.…”

“…Our research group is developing new PEMs based on RX-PTFE films with different crosslinking density by pre-irradiation induced graft polymerization of S and co-monomers and successive sulfonation [14][15][16][17][18][19][20][21]. In previous research we found that using the crosslinker co-monomer, DVB, in the grafting system, resulted in some difference in the properties of the PEMs: (i) the formation of the network structure in the poly(styrene-sulfonic acid) (PS-SA) graft chains effectively suppressed the water uptake of the PEMs due to the restrained PS-SA chains mobility [20], (ii) as observed by XPS analysis, the surfaces of the PEMs grafted by S were C-atom rich, while the surfaces of the PEMs grafted by S together with DVB were F-atom rich [17], (iii) the chemical resistance of the PEMs grafted by S/DVB to the oxidative radicals are much higher than those grafted by S. Also, the increasing in the crosslinking density of the RX-PTFE films has a positive effect on improving the chemical resistance of the PEMs [18,20].…”