Proton Conducting Sulphonated Fluorinated Poly(Styrene) Crosslinked Electrolyte Membranes

Abstract

Potential membranes for polymer electrolyte membrane fuel cell based on crosslinked sulphonated fluorinated polystyrenes (PS) were synthesised in two steps. First, azide‐telechelic polystyrene was obtained by iodine transfer polymerisation of styrene in the presence of 1,6‐diiodoperfluorohexane followed by azido chain‐end functionalisation. Then azide‐telechelic polystyrene was efficiently crosslinked with 1,10‐diazido‐1H,1H,2H,2H,9H,9H,10H,10H‐perfluorodecane under UV irradiation. After 45 min only, almost completion of azide crosslinking could be achieved, resulting in crosslinked membranes with insoluble fractions higher than 95%. The sulphonation of the crosslinked membranes afforded ionic exchange capacities (IECs) ranging from 2.2 to 3.2 meq g–1. The hydration number was shown to be very high (from 30 to 75), depending on both the content of perfluorodecane and of sulphonic acid groups. The morphology of the membranes, assessed by small‐angle X‐ray scattering, was found to be a lamellar‐type structure with two types of ionic domains. For the membrane that exhibited an IEC value of 2.2 meq·g–1, proton conductivity was in the same range as that of Nafion® (120–135 mS·cm–1), whereas the membrane IEC value of 3.2 meq·g–1 showed a proton conductivity higher than that of Nafion® in liquid water from 25 to 80 °C, though a high water uptake.

(Co)polymers of Chlorotrifluoroethylene: Synthesis, Properties, and Applications

“…491 This photo-crosslinking strategy was recently confirmed on original PEMFC. 492 Patel et al 484 used the same technique described above to prepare poly(CTFE-co-VDF)-g-poly(SSA) graft copolymers. The intention was to blend them with zeolites to prepare proton-conducting membranes.…”

“…This time the hydroxyl moiety of hydroxyl ethyl acrylate (HEA) was used in an esterification reaction with a diacid (sulfosuccinic acid) . This photo-cross-linking strategy was recently confirmed on original PEMFC . Patel et al used the same technique described above to prepare poly(CTFE- co -VDF)- g -poly(SSA) graft copolymers.…”

Radical copolymerization of chlorotrifluoroethylene with 4‐bromo‐3,3,4,4‐tetrafluorobut‐1‐ene

“…They can also be involved in further reactions such as atom transfer radical polymerization or azidation. In the later case, the presence of azido groups may allow cross‐linking by photopolymerization . This topic is currently under investigation in our group and the results will be reported in due course.…”

Synthesis, Characterization and UV‐Crosslinking of Aromatic (Co)polycarbonates Bearing Pendant Azido Groups

“…The presence of pendant azido groups in (co)polycarbonates provide opportunities for post‐modifications via reactions such as CuAAC click reaction, azide‐norbornene cycloaddition, azide‐maleimide cycloaddition, azide‐thioacid amidation and reduction of azido to amine [39] . Additionally, azido functional group can be decomposed either thermally or photochemically into highly reactive nitrene intermediate which can subsequently form intra‐ and inter‐molecular bonds with neighboring polymer backbone to produce cross‐linked structures [58–60] . The nitrenes are so reactive that they attack various chemical bonds including C−C,C−H and−NH bonds as shown in Scheme 3 [61] …”

“…[39] Additionally, azido functional group can be decomposed either thermally or photochemically into highly reactive nitrene intermediate which can subsequently form intra-and inter-molecular bonds with neighboring polymer backbone to produce cross-linked structures. [58][59][60] The nitrenes are so reactive that they attack various chemical bonds including CÀ C,CÀ H andÀ NH bonds as shown in Scheme 3. [61] Polycarbonate films (thickness = 40-50 μm) were prepared by solution casting from chloroform solution and were exposed to UV irradiation at 254 nm under ambient conditions.…”