From Nanodroplets by the Ouzo Effect to Interfacial Nanolenses

Abstract

Polymerizing nanodroplets at solid-liquid interfaces is a facile solution-based approach to the functionalization of large surface areas with polymeric lens-shaped nanostructures. In this work, we have applied a one-pot approach to obtain polymeric nanolenses with controlled sizes and densities. We take advantage of the formation mechanism by the direct adsorption of nanodroplets from a surfactant-free microemulsion onto an immersed hydrophobic substrate. The interfacial nanodroplets were photopolymerized to produce polymeric nanolenses on the substrate surface. The surfactant-free microemulsion of the monomer nanodroplets was obtained through the spontaneous emulsification (i.e., ouzo effect) in the tertiary system of ethanol, water, and precusor monomer. The size of nanolenses on the surface was adjusted by the nanodroplet size, following a linear relationship with the ratio of the components in the microemulsion. This simple approach is applicable to produce nanolenses over the entire surface area or on any specific area at will by depositing a drop of the microemulsion. Possessing high optical transparency, the resulting substrates may have potential application as functional biomedical supporting materials or effective light-harvesting coatings.

Rayleigh–Taylor instability by segregation in an evaporating multicomponent microdroplet

“…For this we mix 30 mg silicone oil with 5970 mg 1,2-hexanediol aqueous solution in a glass container and sonicate it for 10 min. We performed evaporation experiments on a hydrophobized glass slide coated by octadecyltrichlorosilane (OTS, Sigma-Aldrich, >90 %) (Peng et al 2014). Before usage, the substrates were cleaned sequentially by 15 min sonication in 99.8 % ethanol and 5 min in Milli-Q water, and subsequently dried with compressed N 2 flow for 30 s. The droplet in each experiment was deposited by a glass syringe with a full metal needle (Hamilton, 10 μl, Model 701 NWG SYR, Cemented NDL).…”

Sequential Evaporation–Induced Formation of Polymeric Surface Microdents via Ouzo Effect

“…This provides an approach to tune the size of the microdents. Since the ternary solution of toluene/water/acetone was prepared by mixing water–acetone solution and PS–toluene solution in proportion, the nucleation of water droplets can be controlled by adjusting water concentration in water–acetone solution18,19b and the PS film thickness can be tuned by PS concentration in PS–toluene solution.…”

“…Recently, “Ouzo effect” was applied to fabricate micro/nanostructures, such as micro/nanodroplets, micro/nanoparticles, and micro/nanolenses 14b,18. “Ouzo effect” is referred to the nucleation of tiny oil droplets after water is added into a Greek drink of Ouzo .…”

“…Instead of adding water into ethanol–oil mixture, evaporation of ethanol in an Ouzo drop can also trigger Ouzo effect . The Ouzo effect provides an efficient approach to produce microdroplets that in turn serve as templates for the formation of micro/nanostructures . Compared with the existed methods, micro/nanostructure fabrication via Ouzo effect can be conducted without any special setups and complex operations.…”

Simple Nanodroplet Templating of Functional Surfaces with Tailored Wettability and Microstructures

“…[1] These nanodroplets are 10 nm to 1 mmi nh eight and 100 aL to 100 fL in volumew ith potential applications in 3D printing of optical and electronic devices, [2][3][4] bio-microarrays, [5][6][7] highly efficient chemicalm icroreactors, [8][9][10] heatt ransfer, [11][12][13] and laboratoryon-chip devices. [14][15][16][17] Several techniques have been reported to generates uch small droplets, including nanodeposition, [18,19] emulsion capturing, [20] and controlled dewetting of thin polymer films. [21][22][23] Among them, the solvent-exchange process, which is as imple and versatile approacht op repare surface nanodroplets or nanobubbles, is capable of producing al arge number of surface nanodroplets on variouss ubstrates immersedi nl iquids.…”