Leveraging 2D Material-Casting Polymer Interactions for Scalable Fabrication of Damage-Sealed Atomically Thin Membranes

Scalable synthesis and integration of two-dimensional (2D) materials with porous supports are crucial for advancing atomically thin membranes. Phase inversion of polymers cast on 2D materials synthesized via scalable chemical vapor deposition (CVD) provides a straightforward route to porous supports, yet the underlying mechanisms remain unclear. We systematically investigate phase inversion of poly(ether sulfone) (PES) on three model substrates: bare Cu, continuous monolayer CVD graphene on Cu, and unmerged CVD graphene domains on Cu. On bare Cu, PES forms dense, nonporous supports that block transport, whereas on CVD graphene, PES yields porous supports (∼300-500 nm) that provide support and allow transport. These differences arise from PES-substrate adhesion governing solvent-nonsolvent exchange. On unmerged graphene domains, PES forms a hybrid structure: porous on graphene, dense on Cu, effectively sealing damages while preserving intrinsic as well as introduced lattice defects enabling selective transport (KCl/lysozyme, ∼306.5; l-tryptophan/lysozyme, ∼75.5; and vitamin B₁₂/lysozyme, ∼27.3). These insights enable facile and scalable damage-sealed atomically thin membrane fabrication and reveal 2D materials as model platforms to probe polymer demixing via phase inversion.