Next-Generation Asymmetric Membranes Using Thin-Film Liftoff

Abstract

For the past 30 years, thin-film membrane composites have been the state-of-the-art technology for reverse osmosis, nanofiltration, ultrafiltration, and gas separation. However, traditional membrane casting techniques, such as phase inversion and interfacial polymerization, limit the types of material that are used for the membrane separation layer. Here, we describe a novel thin-film liftoff (T-FLO) technique that enables the fabrication of thin-film composite membranes with new materials for desalination, organic solvent nanofiltration, and gas separation. The active layer is cast separately from the porous support layer, allowing for the tuning of the thickness and chemistry of the active layer. A fiber-reinforced, epoxy-based resin is then cured on top of the active layer to form a covalently bound support layer. Upon submersion in water, the cured membrane lifts off from the substrate to produce a robust, freestanding, asymmetric membrane composite. We demonstrate the fabrication of three novel T-FLO membranes for chlorine-tolerant reverse osmosis, organic solvent nanofiltration, and gas separation. The isolable nature of support and active-layer formation paves the way for the discovery of the transport and selectivity properties of new polymeric materials. This work introduces the foundation for T-FLO membranes and enables exciting new materials to be implemented as the active layers of thin-film membranes, including high-performance polymers, two-dimensional materials, and metal–organic frameworks.

The stability of a graphene oxide (GO) nanofiltration (NF) membrane in an aqueous environment: progress and challenges

“…14A). 117 In detail, the active layer GO is cast onto a glass pane, and the thickness and chemistry of the GO selective layer can be facilely tuned during this casting process. Then, a fiber-reinforced, epoxy-based resin is cured on top of the GO layer to form a covalently bound support layer.…”

“…After submersion in water, the cured membrane lifts off from the substrates, providing a robust, freestanding, asymmetric GO composite membrane. 117 Compared with a common scenario such as the deposition of a GO film by filtering a GO suspension on substrates, the T-FLO method results in much stronger adhesion between the GO membrane and substrates. 118 As a result, the obtained T-FLO-GO membrane can remain stable in water for at least 30 days (Fig.…”

“…14 (A) GO NF membranes based on thin-film liftoff (T-FLO). 117 (a) Fabrication of thin-film lift off (T-FLO) membranes. The thin-film interference pattern created by a several-hundred-nanometers-thick active layer can be seen in the top right photograph.…”

Ultrapermeable nanofiltration membranes with tunable selectivity fabricated with polyaniline nanofibers

“…1,2 Membrane technology offers a solution with high selectivity, high efficiency, and low energy consumption, which has been widely applied in desalination and wastewater treatment for providing fresh water beyond the hydrological cycle. 3,4 Nanofiltration (NF) is a membrane-based separation process with precise nanosized molecular sieving capability and mild operating conditions. 5 NF membranes with different molecular weight cut-offs (MWCO) are designed for increasingly important industrial applications, such as monovalent and divalent salt screening, 6,7 molecular weight-based sieving of organics, 8–10 and concentration of high value-added materials.…”

Fruit ripeness sensors based on poly(lactic acid)/polyaniline solution blow‐spun fibrous membranes

“…22 However, the device sensitivity can be improved by a new thin-film fabrication technique recently developed. 23 The design of highly conductive materials by processing conjugated polymers into nanofibrous structures has led to the development of electrical devices of great scientific and commercial interest, resulting from their remarkably high surface area, such as smart wearables, 24 organic solar cells, 25 biosensors, 26 gas sensor, 14 gas separation membrane, 27 and particulate matter filters. 28 Specifically, for gas sensors, nanofibers offer more advantages than thin films, 29,30 since they have a higher surface area, and the fibrillar structure allows for better diffusivity of gases in the sensitive layer.…”