The study of proton conductivity processes has gained intensive attention in the past decades due to their potential applications in chemical sensors, electrochemical devices, and energy generation. The scientific community has focused its efforts on the development of high‐performing polymeric membranes as proton exchange membranes (PEMs) for fuel cell (FC) applications. In particular, high conductivity at different humidity and temperature and enhanced chemical and mechanical stability under operative conditions are considered the main goals to be reached. The design of mixed‐matrix membranes (MMMs) based on conductive polymers and inorganic fillers is an approach commonly used for achieving materials with improved conductive and mechanical properties. In the last five years, the use of metal‐organic frameworks (MOFs) as fillers for conductive MMMs has rapidly grown for their intrinsic stability and structural versatility. The recent progress around the proton conductivity of MOF based composite membranes on PEMs for FC applications is critically reviewed.

In the last decade, interest in the functionalization of surfaces and materials has increased dramatically. In this regard, click chemistry deserves a central focus because of its mild reaction conditions, high efficiency, and easy post‐treatment. Among such novel click reactions, those that do not require any metal catalyst are of special interest, as metals may have undesirable effects in many fields. In this Review, the backgrounds and application of such metal‐free click reactions for the modification of surfaces are highlighted.

The realization of covalent adaptable networks with excellent mechanical and dynamic properties remains a major challenge. Herein, the acylsemicarbazide (ASC) moieties with dynamic reversibility and multiple hydrogen bonding were disclosed and used to prepare transparent, high modulus, and malleable polymer networks. It was found that the ASC moiety can reversibly generate isocyanate and hydrazide at elevated temperatures, that is, exhibiting dynamic reversibility. ASC can also produce the disordered multiple hydrogen bonds that contribute to superior mechanical strength for dynamic polymers. The hydrogen bonding in ASC moieties can diminish the energy barrier for the cleavage of dynamic covalent bonds, and the dissociation of ASC moieties further promotes the disruption of hydrogen bonds, showing the synergistic dynamic effects. ASC moieties provide a valuable molecular engineering opportunity toward high-performance dynamic polymer materials. The polymer containing ASC moieties possesses excellent optical transparency, superb mechanical performance (Young's modulus up to 1.7 GPa), together with malleable and healing properties.

The highly resonance-stabilized urea covalent moiety can be made dynamic through mediation of metal salts, thus allowing the development of novel classes of self-healing polymer materials with excellent healing efficiency.

The preparation and characterization of composite polybenzimidazole (PBI) membranes containing zeolitic imidazolate framework 8 (ZIF-8) and zeolitic imidazolate framework 67 (ZIF-67) is reported. The phosphoric acid doped composite membranes display proton conductivity values that increase with increasing temperatures, maintaining their conductivity under anhydrous conditions. The addition of ZIF to the polymeric matrix enhances proton transport relative to the values observed for PBI and ZIFs alone. For example, the proton conductivity of PBI@ZIF-8 reaches 3.1 × 10−3 S·cm−1 at 200 °C and higher values were obtained for PBI@ZIF-67 membranes, with proton conductivities up to 4.1 × 10−2 S·cm−1. Interestingly, a composite membrane containing a 5 wt.% binary mixture of ZIF-8 and ZIF-67 yielded a proton conductivity of 9.2 × 10−2 S·cm−1, showing a synergistic effect on the proton conductivity.