Spontaneous and rapid self-healing ionogels membrane based on dual dynamic crosslinking networks strategy for high-efficiency CO2 separation

Abstract

Ionogels membranes have excellent solubility selectivity for CO₂ and show great potential for CO₂ separation and capture. However, the poor mechanical properties, susceptibility to damage, and short service life of ionogels membranes have limited their applications. Herein, we employed a novel strategy involving the construction of dynamic dual self-healing networks based on a double network (DN) structure to enhance the self-healing efficiency and mechanical performance of ionogels membranes. The first dynamic chemical cross-linking supramolecular network was formed based on imine bonds. The second dynamic physical cross-linking network was established between the UPy units, which served as a sacrificial network to dissipate stresses and generally enhance the mechanical properties of the DN membranes. When the free ionic liquids (ILs, [EMIM]DCA) were added at 60 wt%, the CO₂ permeability (P_CO2) was 310 Barrer, and the ideal CO₂/N₂ selectivity (α (CO₂/N₂)) was 62, approaching the 2019 Robeson upper bound. Due to the synergistic effect of the dual self-healing networks, the self-healing efficiency of DN membrane was greatly improved. The DN (UPy 5 wt%) membrane exhibited a high stress healing efficiency (σHE) of 95% and a high strain healing efficiency (εHE) of 125% after 1 h of self-healing at room temperature. These values significantly exceeded the self-healing efficiency observed with single self-healing network and approached the upper bound for tensile strength as a function of self-healing time. Additionally, the ionogels membrane exhibited excellent functional recovery and reproducibility. The ionogels membrane underwent three puncture/healing (1 h) experiments, achieving P_CO2 self-healing efficiency of 96.8%, 98.1%, and 97.3%, and α(CO₂/N₂) self-healing efficiency of 89.7%, 87.4%, and 90.3%, respectively. Therefore, the construction of dual self-healing networks is an effective strategy to prepare high performance self-healing gas separation membranes.