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Breath-figure self-assembly is the
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Breath-figure self-assembly is the self-assembly
Self-assembly is a process in which a disordered system of pre-existing components forms an organized structure or pattern as a consequence of specific, local interactions among the components themselves, without external direction. When the ...
process of formation of honeycomb
A honeycomb is a mass of hexagonal prismatic wax cells built by honey bees in their nests to contain their larvae and stores of honey and pollen.
Beekeepers may remove the entire honeycomb to harvest honey. Honey bees consume about of honey ...
micro-scaled polymer patterns by the condensation of water droplets. "Breath-figure" refers to the fog that forms when water vapor contacts a cold surface. In the modern era systematic study of the process of breath-figures water condensation was carried out by Aitken and Rayleigh, among others. Half a century later the interest to the breath-figure formation was revived in a view of study of atmospheric processes, and in particular the extended study of a dew formation which turned out to be a complicated physical process. The experimental and theoretical study of dew formation has been carried out by Beysens. Thermodynamic and kinetic aspects of dew formation, which are crucial for understanding of formation of breath-figures inspired polymer patterns will be addressed further in detail.
Breakthrough in the application of the breath-figures patterns was achieved in 1994–1995 when Widawski, François and Pitois reported manufacturing of polymer
A polymer (; Greek '' poly-'', "many" + ''-mer'', "part")
is a substance or material consisting of very large molecules called macromolecules, composed of many repeating subunits. Due to their broad spectrum of properties, both synthetic a ...
films with a self‐organized, micro-scaled, honeycomb
A honeycomb is a mass of hexagonal prismatic wax cells built by honey bees in their nests to contain their larvae and stores of honey and pollen.
Beekeepers may remove the entire honeycomb to harvest honey. Honey bees consume about of honey ...
morphology using the breath-figures condensation process. The reported process was based on the rapidly evaporated polymer solutions exerted to humidity. The introduction into experimental techniques involved in manufacturing of micropatterned surfaces is supplied in reference 1; image representing typical breath-figures-inspired honeycomb pattern is shown in Figure 1.
The main physical processes involved in the process are: 1) evaporation of the polymer solution; 2) nucleation of water droplets; 3) condensation of water droplets; 4) growth of droplets; 5) evaporation of water; 6) solidification of polymer giving rise to the eventual micro-porous pattern. This experimental technique allows obtaining well-ordered, hierarchical, honeycomb surface patterns. A variety of experimental techniques were successfully exploited for the formation of breath-figures self-assembly induced patterns including drop-casting, dip-coating
image:Dip coating.svg, A schematic of the continuous dip coating process.
Roll of coarse cloth
Cloth
Bath
Liquid material
Rollers
Oven
Scrapers
Excess liquid falls back
A coating remains on the fabric cloth.
Dip coating is an industrial ...
and spin-coating
Spin coating is a procedure used to deposit uniform thin films onto flat substrates. Usually a small amount of coating material is applied on the center of the substrate, which is either spinning at low speed or not spinning at all. The substrate ...
. Adapted techniques to achieve varied pattern morphologies and hierarchical designs have also been developed. The characteristic dimension of pores is usually close to 1 µm, whereas the characteristic lateral dimension of the large-scale patterns is ca.
CA or ca may refer to:
Businesses and organizations Companies
* Air China (IATA airline code CA)
* CA Technologies, a U.S. software company
* Cayman Airways, a Cayman Islands airline
* Channel America, a defunct U.S. television network
* Classi ...
10–50 µm. {{open accessSee also
*Self-assembly
Self-assembly is a process in which a disordered system of pre-existing components forms an organized structure or pattern as a consequence of specific, local interactions among the components themselves, without external direction. When the ...
* Marangoni effect
The Marangoni effect (also called the Gibbs–Marangoni effect) is the mass transfer along an interface between two phases due to a gradient of the surface tension. In the case of temperature dependence, this phenomenon may be called thermo-capill ...
* Droplet cluster
Droplet cluster is a self-assembled levitating monolayer of microdroplets usually arranged into a hexagonally ordered structure over a locally heated thin (about 1 mm) layer of water. The droplet cluster is typologically similar to co ...
References