Original Fuel‐Cell Membranes from Crosslinked Terpolymers via a “Sol–gel” Strategy

Abstract

Hybrid organic/inorganic membranes that include a functionalized (‐SO3H), interconnected silica network, a non‐porogenic organic matrix, and a ‐SO3H‐functionalized terpolymer are synthesized through a sol–gel‐based strategy. The use of a novel crosslinkable poly(vinylidene fluoride‐ter‐perfluoro(4‐methyl‐3,6‐dioxaoct‐7‐ene sulfonyl fluoride)‐ter‐vinyltriethoxysilane) (poly(VDF‐ter‐PFSVE‐ter‐VTEOS)) terpolymer allows a multiple tuning of the different interfaces to produce original hybrid membranes with improved properties. The synthesized terpolymer and the composite membranes are characterized, and the proton conductivity of a hybrid membrane in the absence of the terpolymer is promising, since 8 mS cm−1 is reached at room temperature, immersed in water, with an experimental ion‐exchange‐capacity (IECexp) value of 0.4 meq g−1. Furthermore, when the composite membranes contain the interfaced terpolymer, they exhibit both a higher proton conductivity (43 mS cm−1 at 65 °C under 100% relative humidity) and better stability than the standard hybrid membrane, arising from the occurrence of a better interface between the inorganic silica and the poly[(vinylidene fluoride)‐co‐hexafluoropropylene] (poly(VDF‐co‐HFP)) copolymer network. Accordingly, the hybrid SiO2‐SO3H/terpolymer/poly(VDF‐co‐HFP) copolymer membrane has potential use as an electrolyte in a polymer‐electrolyte‐membrane fuel cell operating at intermediate temperatures.

Proton Conducting Sulphonated Fluorinated Poly(Styrene) Crosslinked Electrolyte Membranes

“…The low dependence of temperature to proton conductivity may be related to a continuous network of ionic domains, thus facilitating proton migration [52]. This was confirmed by SAXS measurements which showed that lamellar structure resulted from both M50 and M60 membranes [49] at 100% RH.…”

“…The general feature is a gradual decay of intensity scaling as q -2 over more than one decade of angles which may be assigned to a lamellar morphology [46][47][48][49]. Two very broad scattering maxima modulate this intensity decay and can be observed at about 0.1 and 0.01 Å -1 .…”

Polymer-Layered Silicate Nanocomposite Membranes for Fuel Cell Application

“…PEMFCs operating above 100 C are preferred over that operating at low temperature to overcome several disadvantages (like CO catalyst poisoning and heat and water management) associated with the later [1,6,7,24]. Inferior proton conductivity of Nafion at high temperature and low humidity has prompted towards the development of new polymer membranes such as polyethersulfone (PES) [25,26], polyetheretherketone (PEEK) [27][28][29][30], polyimide (PI) [31][32][33], polybenzimidazole (PBI) [34][35][36][37][38][39][40][41], polystyrene-acrylonitrile (SAN) [42,43], and polyvinylidene fluoride (PVDF) [44][45][46] to meet the U. S. Department of Energy (DOE) targets [47,48].…”

Fuel Cell Membranes Based on Polymer-Modified Silica Colloidal Crystals and Glasses: Proton Conductivity and Fuel Cell Performance

“…[4,5] Hybrid organic-inorganic materials may meet all these requirements. [6][7][8] Recently, we reported the development of such hybrid systems, where a rigid highly ordered silica colloidal crystal containing a continuous network of nanopores provides mechanical and thermal stability, non-swelling and water retaining properties, while polymer brushes grown on the surface of silica and having sulfonic groups provide proton conductivity. [9] Highly-ordered silica colloidal crystals could serve as good inorganic matrix materials for DMFC proton conductive membranes, however they are limited by size, since it is challenging to obtain uniform and evenly thick free-standing membrane of large size (e.g.…”