Creates Porous Support on Graphene, Sealing Tears and Damages
This fabrication approach casts polymers on 2D materials (e.g. graphene) for sealing damaged regions and fabricating atomically thin membranes. Atomically thin 2D materials are promising platforms for membrane separations, with graphene standing out because of its atomic-scale thickness, tunable defects that can act as selective nanopores, high mechanical strength, and chemical robustness. These materials have been studied for ionic and molecular sieving, proton exchange membranes, isotope separation, energy harvesting, gas separation, desalination, nanofiltration, and dialysis, but practical use is dependent on scalable integration with porous supports for preserving membrane integrity and compatibility. In parallel, polymer phase inversion offers a route to porous supports with tunable morphology, low cost, and high scalability, although the behavior of polymer solutions cast directly on 2D materials remain insufficiently understood. In 2023, the global graphene membrane market size was valued at approximately $200 million and is expected to grow to $1.2 billion by 2032, with a compound annual growth rate (CAGR) of 22.5%.
Researchers at the University of Florida identified a fabrication approach for casting graphene polymers on 2D materials to fabricate atomically thin membranes. The researchers used unmerged chemical vapor deposition (CVD) graphene domains on copper and identified the polymer forms a dense, nonporous layer on bare copper, a porous layer on continuous graphene, and a hybrid morphology on partial graphene coverage, with porous polymer over graphene regions and dense polymer over exposed copper. This structure helps automatically seal larger damaged regions while preserving selective transport through graphene-based membrane areas. Sealing damages is essential to fabricate atomically thin membranes at practically relevant separation length scales.
Application
This approach creates porous support while sealing large tears, thereby enabling practical separations for dialysis, food processing, pharmaceuticals, and water treatment
Advantages
- Dense polymer regions impede salt and small-molecule transport, helping seal cracks, tears, and other large defects in CVD graphene
- Porous polymer regions preserve intrinsic and nanoscale graphene defects, functioning as selective nanopores
- On unmerged graphene domains, the process creates a hybrid structure with porous regions over graphene and dense regions over exposed copper
- On continuous CVD graphene, the polymer forms porous supports of about 300–500 nm, adhering well to graphene and supporting it effectively for membrane applications
Technology
The technology casts polyether sulfone onto a 2D-material-coated substrate and induces phase inversion. The differences in polymer-substrate adhesion change the solvent and nonsolvent exchange behavior during de-mixing, leading to different outcomes on different surfaces: dense, relatively nonporous polymer on bare copper; porous support on continuous graphene; and a combined dense/porous structure on partially covered surfaces. In the disclosed membrane, a substrate contacts a 2D material layer, and a phase-inverted polymer contacts that 2D material layer; the 2D layer may be continuous or discontinuous. Thin membranes achieve unprecedented performance across a broad spectrum of applications, including ionic/molecular sieving, proton exchange membranes, isotope separation, energy harvesting, gas separation, desalination, nanofiltration, and dialysis.
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