Adsorption-Assisted Interfacial Polymerization toward Ultrathin Active Layers for Ultrafast Organic Permeation

Abstract

Thin-film composite (TFC) membranes show exceptional permeation properties of key importance for many separations. However, their design and development need ultrathin and defect-free nanofilms as the active layer to alleviate the bottleneck of permeation-rejection trade-off. Here, a 25 nm thick film is fabricated on a porous support by introducing polydopamine (PDA) as an adsorption layer, imparting a unique adsorption-assisted interfacial polymerization (IP) strategy. The PDA layer efficiently captures and enriches amine monomers even from ultradilute solution toward uniform stacking on the support, thus generating ultrathin and defect-free films after polymerization. This is superior to the defective one from conventional IP. Such an active layer features ultrafast permeation for organics, favorable solute rejection, and excellent operation stability. Particularly, the acetone permeance of this new TFC membrane reaches 96.3 L m h bar, which exceeds that from conventional IP by more than 10 times, ranking among one of the highest performances reported to date. More significantly, the pernicious permeation-rejection trade-off of the TFC membrane is thus alleviated. Besides, this strategy is facile, versatile, and easy to scale-up, giving controllable physical and chemical structures to the active layer. This study may pave a way to well-design highly efficient film materials for various transport and separation applications.

Beetle‐Inspired Assembly of Heterostructured Lamellar Membranes with Polymer Cluster–Patterned Surface for Enhanced Molecular Permeation

“…For example, n ‐hexane and toluene permeances of GO membrane drop by, respectively, 21.9% and 24.0% by PDMS film, contrasting to the times increase by PDMS clusters. This should be caused by the high transport resistance of polymer film (permeance < 2.0 L m −2 h −1 bar −1 ; Figure S24, Supporting Information), resulted from small‐sized transport paths (i.e., free volume cavities) . This finding also highlights the advantage of surface modification of polymer clusters, which can manipulate dissolution property of solvents while not generating additional transport resistance.…”

“…Similarly, Qiao et al achieved an enhanced CO 2 /N 2 selectivity from ≈1 to 34 by coating a CO 2 ‐philic polyactive film on a metal‐organic framework membrane . However, the permeance of those polymer film–coated lamellar membranes is usually sacrificed because the dense polymer film renders small‐sized transfer channels (i.e., free‐volume cavities) . And the increase of membrane thickness leads to additional mass transfer resistance .…”

Ultra-permeable polyamide membranes harvested by covalent organic framework nanofiber scaffolds: a two-in-one strategy

“…This unique method provides a promising way for improving the permeance of PA layers through substrate reconstruction. Similarly, various materials have been utilized for substrate reconstruction to reduce the thickness of the PA layers, such as carbon nanotubes,12–15 copper hydroxide nanostrands,16 cellulose nanocrystals,17 polydopamine18,19 and polyphenol 20,21. It is noteworthy that, for the state-of-the-art NF membranes, the thickness of the PA layers has been successfully reduced to ∼10 nm 6,12,15,22.…”

Monitoring the Interfacial Polymerization of Piperazine and Trimesoyl Chloride with Hydrophilic Interlayer or Macromolecular Additive by In Situ FT-IR Spectroscopy

“…Additionally, Ren et al used FT-IR microscopy for IP reaction of microporous polymer film formed in the aqueous/organic interface for polyesterification by choosing the adequate phenol monomer [29]. Yang et al reduced the IP reaction rate of piperazine (PIP) and trimesoyl chloride (TMC) reaction system to a certain extent by introducing interlayers between the porous substrate and the polyamide layer [30][31][32]. Tan et al added the macromolecular additive of polyvinyl alcohol (PVA) in the aqueous solution of PIP and obtained the Turing structure [33].…”