Precise Size‐Selective Sieving of Nanoparticles Using a Highly Oriented Two‐Dimensional Supramolecular Polymer

Abstract

The development of size‐selective membranes with well‐defined nanopores towards the precise separation of nanometer‐sized substances is a challenging task to achieve. Here a supramolecular membrane is presented that comprises a highly oriented, honeycomb‐like, 2D supramolecular polymer on a polycarbonate filter support. It enables precise size‐selective sieving of colloidal nanoparticles (NPs). Owing to the uniform parallel‐aligned nanocavities within the 2D supramolecular polymers, the composite membrane shows a high size‐selectivity with a sub‐nanometer accuracy in the cutoff size of about 4.0 nm. In principle, the species of size‐separable particles are unlimited, as demonstrated by quantum dots, noble metal, and metal oxide NPs. This supramolecular membrane combined with filtration advances the potential of NPs in terms of their monochromatic emission and size monodispersity, and also enables rapid removal of small magnetic NP adsorbents that are otherwise difficult to capture.

Two-Dimensional Supramolecular Ionic Frameworks for Precise Membrane Separation of Small Nanoparticles

“…2.2 nm as analyzed from the data for two membranes (M50 and M100) of different thicknesses (Figures S27 and S28). In comparison to the published separation results of membranes comprising of frameworks bearing various pore structures and compositions (Table S7), ,,,− this value represents a very smaller threshold in the present stage. It should be noted that the particles with size greater than the measured pore size (1.92 nm) of the framework structure occupy about 4.33% in the filtrate (Figure f), implying that this portion of nanoparticles does not pass through the regular pores in the membrane.…”

Stimuli-Responsive Two-Dimensional Supramolecular Polymers Based on Trinuclear Platinum(II) Scaffolds: Reversible Modulation of Photoluminescence, Cavity Size, and Water Permeability

“…Recently, we reported the first honeycomb-like 2D SP constructed with dimeric Pt···Pt building units of a novel trinuclear Pt II complex, which was solution-processable into a multifunctional separation membrane that enables not only efficient capture of anionic Pt II species but also precise size-selective sieving of nanoparticles . Motivated and encouraged by the previous performance, we herein demonstrate an acid–base responsive 2D SP formed via noncovalent Pt···Pt and π···π stacking interactions.…”

“…47,48 Recently, we reported the first honeycomb-like 2D SP constructed with dimeric Pt•••Pt building units of a novel trinuclear Pt II complex, 49 which was solution-processable into a multifunctional separation membrane that enables not only efficient capture of anionic Pt II species but also precise sizeselective sieving of nanoparticles. 50 properties, including adaptive expansion and contraction in cavity size, tunable photoluminescence colors, as well as pHmodulated water transportation (Figure 1b). To the best of our knowledge, this is the first example reported on a stimuliresponsive 2D SP with switchable structures and functionalities.…”

Coordination Cages Selectively Transport Molecular Cargoes Across Liquid Membranes

“…They have been demonstrated to separate ions and heavy metals − but not neutral molecules as yet. The use of such membranes for neutral-molecule separation may help enable the goal of purifying chemical mixtures at a lower energy cost than is currently possible. , Membranes constructed using supramolecular principles have also shown a promising ability to selectively filter compounds based on size − and charge differences.…”