Hydrogen Bond and Dipole-Dipole Interaction Enabling Ultrastable, Quick Responding, and Self-Healing Proton Exchange Membranes for Fuel Cells.

Proton exchange membranes (PEMs) are subject to mechanical degradation, such as microcracks and pinhole formation, under real-world fuel cell operating conditions, which leads to great issues in terms of device death and safety concerns. Therefore, PEMs with self-healing features are imperative but have rarely been used for proton exchange membrane fuel cells (PEMFCs). Here, a dimensionally stable and self-healing PEM is developed by tuning the hydrogen bond and dipole-dipole interactions between the mature perfluorinated sulfonic acid (PFSA) and a self-healing copolymer, which is specifically synthesized with hexafluorobutyl acrylate (HFBA) and acrylic acid (AA). This hexafluorobutyl acrylate-acrylic acid copolymer (HFBA--AA) is suggested as the key to improving the self-healing efficiency of the blended PFSA/HFBA--AA membrane. This PFSA/HFBA--AA membrane can recover 43.6% of the original tensile strength within only 20 min at 80 °C. This study may pave an avenue toward the development of reliable and durable PEM for fuel cells.