Breath Figure Arrays: Unconventional Fabrications, Functionalizations, and Applications

Abstract

A breath figure (BF) is the water droplet array that forms when moisture comes in contact with a cold substrate. This water droplet array has been widely utilized in the past two decades as a versatile soft template for the fabrication of polymeric porous films. Accordingly, the ordered pores on the polymer films formed with such a method are named a breath figure array (BFA).The BF templating technique is undergoing rapid development. Several unconventional BF processes have been established to prepare porous films with unique morphologies or primary materials, and various newly developed functionalization techniques have significantly improved the performance of polymeric films with BFA, leading to novel applications, including templates, biosensors, and separation membranes. These recent achievements will be described in this Minireview.

Fabrication of macroporous protein-containing films through the reverse emulsions approach featuring β-cyclodextrin-conjugated PEG-PLGA copolymers

“…Normally, materials with pore size below 2 nm are defined as microporous ones, while mesoporous ones have pores from 2 nm to 50 nm, and macroporous ones have pores above 50 nm [5] . Among various porous materials, porous polymeric materials show great potential in application as cell culture substrates [6] , biosensors [7] , selective adsorbents [8] , drug delivery [9] and catalyst supports [10] in the past decades, mainly due to their low cost, light weight, as well as the easy fabrication process and the variety of functionalities based on the diversity of polymeric materials.…”

Homogeneous dewetting on large-scale microdroplet arrays for solution-processed electronics

“…Dewetting phenomena are widely investigated at present since they provide fundamental understanding of microfluid dynamics [1][2][3][4][5][6][7][8] and solutions for practical applications, including microfluidic devices, 1,2 anti-icing surfaces 5 and protein micropatterns. 8 Particularly, dewetting organic semiconductor inks on a smooth surface enables the deposition of organic semiconductor thin films and electronic devices.…”

“…8 Particularly, dewetting organic semiconductor inks on a smooth surface enables the deposition of organic semiconductor thin films and electronic devices. 9 In general, the dewetting process spontaneously occurs in a droplet when the following condition is satisfied: γ gl -γ ls -γ gs o 0 (γ gl , γ ls and γ gs are the gas-liquid, liquid-solid and gas-solid surface tensions, respectively).…”

Fabrication of Durable Honeycomb‐Patterned Films of Poly(ether sulfone)s via Breath Figures

“…Compared with other templating and lithography techniques, the BF process shows advantages of low-cost, easy preparation, and the use of water droplets as sacrificial templates, which are removed spontaneously. [ 11 ] In a typical procedure, the solution of polymers in a highly volatile and water-immiscible solvent is cast onto a substrate under high humidity. The fast evaporation of solvent contributes to a temporarily cold solution-air interface condition in long-term continuous use without causing any dimensional change or physical deterioration.…”