Hydrophilic-hydrophobic multiblock copolymers have been widely demonstrated to exhibit improved performance over that of analogous random copolymers in fuel cell operation. This improvement is attributed to the highly developed phase-separated morphology of the multiblock copolymers. The composition of these hydrophilic and hydrophobic segments can have a drastic effect on the morphology and performance of the multiblock copolymers and the corresponding proton exchange membranes. Thus in order to design better membranes a strong understanding of the structure-property relationship for this class of materials is important.In this paper the effect of backbone structure was investigated by using a series of multiblock copolymers with increasing hydrophilicity. The sulfonated poly(arylene ether sulfone) hydrophilic component was synthesized by reacting three different comonomers, (biphenol, hydroquinone, and sulfonated hydroquinone), with a disulfonated sulfone monomer to form a series of oligomers with increasing ion-exchange capacity (IEC). Multiblock copolymers were synthesized by reacting the highly sulfonated oligomers with partially fluorinated poly(ether ether ketone)s and poly(arylene ether benzonitrile)s hydrophobic oligomers.  The effects of backbone hydrophilicity on the properties of the corresponding membranes were characterized in regard to water adsorption, proton conductivity, mechanical properties, and morphology. In addition the MEA fabrication and performance in fuel cell operation of these membranes will be discussed.

Properties and performance of multiblock copolymers based upon a varying hydrophilicity backbone

247th National Meeting (2014)

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