Hydrophilic–hydrophobic multiblock copolymers based on poly(arylene ether sulfone) via low-temperature coupling reactions for proton exchange membrane fuel cells

Sulfonated hydrocarbon membranes for medium-temperature and low-humidity proton exchange membrane fuel cells (PEMFCs)

“…In related studies, well-defined nano-phase separated morphologies were attained for multiblock copolymers as the block length was increased. This in turn improved the proton conductivity and water uptake of the structures [74,121]. In particular, multiblock copolymers based on sulfonated and non-sulfonated poly(arylene ether sulfone) oligomers exhibited anisotropic swelling behavior (i.e., a lower inplane swelling, but higher through-plane swelling than a random copolymer and Nafion ® with isotropic swelling behaviors).…”

“…McGrath and co-workers first adapted the concept of distinct phase separation in block copolymers to sulfonated aromatic PEMs, such as SPAESs and SPIs, and extensively studied novel sulfonated multiblock copolymers using various sulfonated monomers [73,74,[119][120][121][122][123]. Images of well-defined nano-phase separation were obtained for sulfonated multiblock SPAES copolymers, and the PEMs had high proton conductivity even under low humidity conditions below 40% RH.…”

“…In particular, multiblock copolymers based on sulfonated and non-sulfonated poly(arylene ether sulfone) oligomers exhibited anisotropic swelling behavior (i.e., a lower inplane swelling, but higher through-plane swelling than a random copolymer and Nafion ® with isotropic swelling behaviors). This could be advantageous in actual fuel cell systems operated under low humidified conditions by reducing the effect of dimensional miss-match between hydrocarbon PEM and PFSA ionomer-catalyst [121]. Multiblock copolymers exhibit proton conductivities that are less RH-dependent and higher than that of Nafion ® [124].…”

“…A high dependency on the annealing temperature is more significantly observed in hydrophilic-hydrophobic multiblock copolymers than in randomly sulfonated copolymers. Multiblock copolymers are generally synthesized via a coupling reaction between phenoxide-terminated disulfonated hydrophilic oligomers and coupling agent (e.g., decafluorobiphenyl)-end-capped hydrophobic oligomers with a controlled molecular weight [121]. Multiblock copolymers have two T g values: one from the hydrophilic block (high T g ) and another from the hydrophobic block (low T g ).…”

Investigation on Structure and Behaviours of Proton Exchange Membrane Materials by TEM

“…The proton conductivity of membrane was closely related to their microstructure. In order to improve proton conductivity, McGrath and co-works have synthesized a series of block sulfonated copolymers, which shows higher proton conductivity than that of random sulfonated copolymers at the same of degree of sulfoantion and IEC values [52][53][54]. This is attributed to the different distribution of ion domains in membranes.…”