Toward Microcapsule-Embedded Self-Healing Membranes

Abstract

We herein report the first instance of a self-healing water treatment membrane that restores its water flux and particle rejection properties autonomously. The self-healing membrane is fabricated by embedding microcapsules with a polyurethane shell and an isophorone diisocyanate core within a conventional poly­(ether sulfone) membrane. A dual-surfactant system and polydopamine coating were used to control the size of these microcapsules and avoid capsule buckling. When the membrane structure is physically damaged, the microcapsules release a reactive isocyanate healing agent that reacts with the surrounding water to form a polyurea matrix that plugs the damage. The self-healing was found to recover the water flux and particle rejection of the membrane to 103 and 90% of the original membrane’s performance, respectively. The results of this study show that microcapsule-embedded membranes are a promising approach to fabricating versatile, next-generation membranes that can self-heal.

Surface modification of a BN/ETDS composite with aniline trimer for high thermal conductivity and excellent mechanical properties

“…Therefore, to ensure the durability and stability of nextgeneration electronic devices, proper heat dissipation is essential during operation. [1][2][3] A low thermal resistance between the electronic device surface and the heat sink is required; however, a substantial portion of the thermal resistance of the device depends on the interfacial morphology (i.e., interstitial gaps). A thermal interface material (TIM) can be used to reduce the rough structure and gaps at the interface.…”

Intelligent environmental nanomaterials

“…For example, stimuli responsive materials have been combined with RO membranes to improve their antifouling properties and been incorporated into the membranes to endow the membrane with self-healing capability. [80][81][82][83][84][85][86] In addition, there is increasing interest in combining MD with photothermal materials, which, in response to solar light, generates heat locally with high energy efficiency. 59 All-in-one membrane has been reported to integrate chemical reactions and physical separation in one system, where the trigger-initiated sequential reactions selectively and ondemand degraded and separated water pollutants.…”

“…64 In the past decade, the concept of self-healing has slowly but steadily been appreciated by and applied to environmental fields. Some exploratory works on endowing conventional environmental processes with self-healing materials have been conducted, including but not limited to, water filtration, [83][84][85] oil/water separation, 258 pollutant absorption 259 and antifouling surface. 257,[260][261][262] Depending on the source of self-healing agents, the self-healing materials are categorized into two types: extrinsic and intrinsic self-healing materials.…”

“…In 2016, Kim et al fabricated a self-healing filtration membrane by embedding into PES membrane the extrinsic microcapsules that had PU shell and isophorone diisocyanate core. 84 Once damaged, the healing agent of isocyanate from the broken microcapsules was released and diffused towards the crack sites, followed by reaction with the surrounding water to form polyurea plug to cover the damage sites (Figure 10a). Once healed, the water flux and particle rejection performances of the membrane were recovered to 103% and 90% of the original ones, respectively.…”

Self-healing polymeric materials for membrane separation: an example of a polybenzimidazole-based membrane for pervaporation dehydration on isopropanol aqueous solution

“…Thermally-triggered self-healing on the membranes from damaged surface morphology and properties recovers its separation ability. On the other hand, healing agents-containing microcapsules 19 and microvascular 20 have been embedded in membranes to integrate the autonomous self-healing materials and the function of membrane separations.…”