A hydrophobic tetrapodal molecule is composed of carbazole units at the periphery linked by a phenyl spacer on an adamantane core. Tetrapodal adamantane self-assembles into hollow spherical aggregates with a multilayer membrane in organic media. The spherical assembly size is dependent on the organic solvent used. Hollow spheres can entrap guest molecules within their internal spaces. By increasing the concentrations of tetrapodal molecules, hollow spheres fused into necklace-shaped nanostructures and two-dimensional networks were obtained.
Liquid–liquid
phase separation, a physical transition in which a homogeneous solution
spontaneously demixes into two coexisting liquid phases, has been
a key topic in the thermodynamics of two-component systems and may
find applications in separation, drug delivery, and protein crystallization.
Here we applied a microscale temperature gradient using optothermal
heating of a gold nanoparticle to overcome the experimental difficulties
inherent in homogeneous heating: We aimed at highlighting precise
structural development by avoiding randomly nucleating/growing microdomains.
In response to laser illumination, a single gold nanoparticle immersed
in a binary mixture of aqueous 2,6-dimethylpyridine (lutidine) and N-isopropylpropionamide (NiPPA) was clearly sensitive to
the phase transition of the surrounding liquid as demonstrated by
light-scattering signals: spectral red-shifts and bright-spot images.
The local phase separation encapsulating the gold nanoparticle resulted
in immediate formation and growth of an organic-rich droplet which
was confirmed by Raman spectroscopy. Remarkably, the droplet was stable
under a nonequilibrium steady-state heating condition because of strong
thermal confinement. Microdroplet growth was ascribed to thermocapillary
flow induced by a newly formed liquid–liquid interface around
the hot gold nanoparticle. On the basis of a tracer experiment and
numerical simulation, it is deduced that the transport of solute to
the high-temperature area is driven by this thermocapillary flow.
This study enhances our understanding of phase separation in binary
mixtures induced by microscale temperature confinement.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.