ИСТИНА

Over the years many techniques and methods have been proposed to self-assemble nanoparticles (NPs) at liquid-liquid interfaces. However, vast majority of them are dedicated to reduce of Coulombic repulsion between nanoparticles with salt or “promoters” of aggregation,1,2 to charge a gold core3,4 or to use solvent evaporation.5 However, self-assembly of gold nanoparticles (AuNPs) at a liquid-liquid interface can be achieved by decreasing of the interfacial surface tension rather than decreasing of Coulombic repulsion. Here, propylene carbonate (PC) having an extremely low interfacial surface tension with water was examined towards the formation of lustrous nanofilms even without tetrathiafulvalene (TTF) molecules. Presence of TTF slightly charged wetting properties of AuNPs and allowed them to cross the interface forming new colloid of AuNPs@TTF charged particles in PC (Fig.1A). AuNPs@TTF in PC phase had a distinguishable UV-Vis extinction spectrum from a nanofilm (Fig. 1B). Qualitative calculations confirmed experimental observations. Among potential applications there are: fabrication of ultra-concentrated AuNPs suspensions for ink-jet printing, electrically-driven liquid mirrors, as well as biphasic SERS. Figure 1. (A) Photographs of PC-water system. From left to right: before, right after shaking, and after complete phase separation with and without TTF in the PC phase at the bottom. (B) UV-Vis spectra of the initial solutions, the spectra of the aqueous and PC phases after complete phase separation and the extinction spectra of nanofilms formed at the given LLI. References: 1. V.A.Turek et al, DOI: 10.1021/nn302941k 2. M.P.Konrad et al, DOI: 10.1021/ac4008607 3. E.Smirnov et al, DOI: 10.1021/nn503644v 4. E.Smirnov et al, DOI:10.1039/C6NR00371K 5. Y.-K. Park et al, DOI: 10.1021/cm703498y