Synthesis and Properties of Fluorenyl-Containing Multiblock Sulfonated Poly(Arylene Ether Sulfone) Membranes for Fuel Cell Applications

A series of novel multiblock copolymers containing rigid hydrophilic/soft hydrophobic blocks were synthesized and evaluated for use as proton exchange membranes (PEMs). The multiblock copolymers were prepared by a coupling reaction between phenoxide-terminated sulfonated poly(arylene ether sulfone) oligomer (OSO) and fluorine-terminated poly(arylene ether sulfone) oligomer (FNO). All copolymers produced tough, flexible and transparent membranes by casting from DMSO solution. The resulting membranes displayed good water stability and enhanced proton conductivities comparable to that of the corresponding random ones with similar ion exchange capacity (IEC) values. They also showed slight anisotropic swelling behavior, while isotropic behavior for the random ones. The results revealed that these multiblock copolymers were potential candidates for PEM materials.