Rigid-Flexible Hybrid Proton-Exchange Membranes with Improved Water-Retention Properties and High Stability for Fuel Cells

A novel molecular structural design of rigid-flexible hybrid polymer backbone is proposed for proton-exchange membranes (PEMs) with the objective to preserve the material longevity by enhancing the dimensional stability. The effect of the rigid-flexible hybrid backbone is demonstrated based on performance tests for a series of non-fluorinated polyamide-sulfonimide proton conductors, among which the conductivity of the rigid-flexible hybrid structural PEM is nearly 100% higher than the rigid PEM with almost the same ion-exchange capacity (IEC). The dimensional and mechanical stabilities of these PEMs are better than those of Nafion membranes. The measured conductivity of the rigid-flexible hybrid structural PEM is on the order of 10(-2) Scm(-1).