Controlled open-cell two-dimensional liquid foam generation for micro- and nanoscale patterning of materials

Abstract

Liquid foam consists of liquid film networks. The films can be thinned to the nanoscale via evaporation and have potential in bottom-up material structuring applications. However, their use has been limited due to their dynamic fluidity, complex topological changes, and physical characteristics of the closed system. Here, we present a simple and versatile microfluidic approach for controlling two-dimensional liquid foam, designing not only evaporative microholes for directed drainage to generate desired film networks without topological changes for the first time, but also microposts to pin the generated films at set positions. Patterning materials in liquid is achievable using the thin films as nanoscale molds, which has additional potential through repeatable patterning on a substrate and combination with a lithographic technique. By enabling direct-writable multi-integrated patterning of various heterogeneous materials in two-dimensional or three-dimensional networked nanostructures, this technique provides novel means of nanofabrication superior to both lithographic and bottom-up state-of-the-art techniques.

New structural approach to rationalize the foam film stability of oppositely charged polyelectrolyte/surfactant mixtures

“…Liquid foams are nonequilibrium dispersions of gas in a liquid that are stabilized against drainage and collapse by surface active agents. 1,2 Foams are of huge importance as they are used in a wide range of applications such as oil recovery, firefighting, foods and personal care products. [3][4][5] The stability of foams is important as it determines the lifetime of the product.…”

“Nano-garden cultivation” for electrocatalysis: controlled synthesis of Nature-inspired hierarchical nanostructures

“…8 It can indeed control the topology of the pattern accurately and is widely used in the nanofabrication of semiconductors. [9][10][11][12][13][14][15] Nonetheless, this approach is rather time-consuming and cost-ineffective, hampering its wide applications in different elds. 15,16 Therefore, the bottom-up synthesis is increasingly explored which promises to address the drawbacks of the top-down counterpart.…”

Markov Models of Coarsening in Two-Dimensional Foams with Edge Rupture

“…The missing total number is interpreted as a gel, or a single massive particle of infinite mass. In (2), we find that the rate of cell merging between i and j-gons is…”

“…The similarity between K F i,j and K i,j suggests a gelation in (2), which should be interpreted as a cell with infinitely many sides. In Section 5, we indeed find strong numerical evidence for the gelation of (2) through Monte Carlo simulations of the mean-field model.…”