High temperature proton exchange membranes with enhanced proton conductivities at low humidity and high temperature based on polymer blends and block copolymers of poly(1,3-cyclohexadiene) and poly(ethylene glycol)

• Published in: Polymer (Guilford) Vol. 77; pp. 208 - 217
• Main Authors: Deng, Shawn, Hassan, Mohammad K., Nalawade, Amol, Perry, Kelly A., More, Karren L., Mauritz, Kenneth A., McDonnell, Marshall T., Keffer, David J., Mays, Jimmy W.
• Format: Journal Article
• Language: English
• Published: United States Elsevier Ltd 23.10.2015; Elsevier
• Subjects: Blends; Block copolymers; Conductivity; electrolyte membranes; Exchange; fluorinated polymer; fuel-cell applications; Glycols; INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CHEMISTRY; Membranes; molecular dynamics; Poly(1,3-cyclohexadiene); Poly(ethylene glycol); Polymer blends; Proton exchange membrane; Relative humidity; sulfonated polybenzimidazoles; Proton exchange membrane; Poly(1,3-cyclohexadiene); Poly(ethylene glycol)
• ISSN: 0032-3861; 1873-2291
• DOI: 10.1016/j.polymer.2015.09.033

Hot (at 120 °C) and dry (20% relative humidity) operating conditions benefit fuel cell designs based on proton exchange membranes (PEMs) and hydrogen due to simplified system design and increasing tolerance to fuel impurities. Presented are preparation, partial characterization, and multi-scale modeling of such PEMs based on cross-linked, sulfonated poly(1,3-cyclohexadiene) (xsPCHD) blends and block copolymers with poly(ethylene glycol) (PEG). These low cost materials have proton conductivities 18 times that of current industry standard Nafion at hot, dry operating conditions. Among the membranes studied, the blend xsPCHD-PEG PEM displayed the highest proton conductivity, which exhibits a morphology with higher connectivity of the hydrophilic domain throughout the membrane. Simulation and modeling provide a molecular level understanding of distribution of PEG within this hydrophilic domain and its relation to proton conductivities. This study demonstrates enhancement of proton conductivity at high temperature and low relative humidity by incorporation of PEG and optimized sulfonation conditions. [Display omitted] •Synthesis of sulfonated, aliphatic proton exchange membranes(PEMs) are presented.•Homopolymer PEMs are based on crosslinked, sulfonated poly(1,3-cyclohexadiene).•PEMs incorporate poly(ethylene glycol) as a blend and as a block copolymer.•PEMs display high proton conductivities even at low humidity and high temperature.•Morphologies were studied using a host of experimental and simulation methods.