Vacuum-Assisted Self-Healing Amphiphilic Copolymer Membranes for Gas Separation

Membrane gas separation provides a multitude of benefitsover alternativeseparation techniques, especially in terms of energy efficiency andenvironmental sustainability. While polymeric membranes have beenextensively investigated for gas separations, their self-healing capabilitieshave often been neglected. In this work, we have developed innovativeself-healing amphiphilic copolymers by strategically incorporatingthree functional segments: n-butyl acrylate (BA), N-(hydroxymethyl)acrylamide (NMA), and methacrylic acid(MAA). Utilizing these three functional components, we have synthesizedtwo distinct amphiphilic copolymers, namely, AP(NMA) (PBA (x) -co-PNMA (y) ) and AP(MAA) (PBA (x) -co-PMAA(y)). These copolymers have beenmeticulously designed for gas separation applications. During thecreation of these amphiphilic copolymers, BA and NMA segments wereselected due to their vital role in the ease of tuning mechanicaland self-healing properties. The functional groups (-OH and-NH) present on the NMA segment interact with CO2 through hydrogen bonding, thereby boosting CO2/N-2 separation and achieving superior selectivity. We assessedthe self-healing potential of these amphiphilic copolymer membranesusing two distinct strategies: conventional and vacuum-assisted self-healing.In the vacuum-assisted approach, a robust vacuum pump generates asuction force, leading to the formation of a cone-like shape in themembrane. This formation allows common fracture sites to adhere andtrigger the self-healing process. As a result, AP(NMA) maintainsits high gas permeability and CO2/N-2 selectivityeven after the vacuum-assisted self-healing operation. The ideal CO2/N-2 selectivity of the AP(NMA) membranealigns closely with the commercially available PEBAX-1657 membrane(17.54 vs 20.09). Notably, the gas selectivity of the AP(NMA) membrane can be readily restored after damage, in contrast to thePEBAX-1657 membrane, which loses its selectivity upon damage.