Nanoparticle Assembly and Transport at Liquid-Liquid Interfaces

Abstract

The self-assembly of particles at fluid interfaces, driven by the reduction in interfacial energy, is well established. However, for nanoscopic particles, thermal fluctuations compete with interfacial energy and give rise to a particle-size-dependent self-assembly. Ligand-stabilized nanoparticles assembled into three-dimensional constructs at fluid-fluid interfaces, where the properties unique to the nanoparticles were preserved. The small size of the nanoparticles led to a weak confinement of the nanoparticles at the fluid interface that opens avenues to size-selective particle assembly, two-dimensional phase behavior, and functionalization. Fluid interfaces afford a rapid approach to equilibrium and easy access to nanoparticles for subsequent modification. A photoinduced transformation is described in which nanoparticles, initially soluble only in toluene, were transported across an interface into water and were dispersed in the water phase. The characteristic fluorescence emission of the nanoparticles provided a direct probe of their spatial distribution.

Interfacial liquid-state surface-enhanced Raman spectroscopy

“…The calculated area and the corresponding interfacial tensions are used to numerically determine the interfacial energy, which is a function of orientation angle and vertical displacement with respect to the interface (see Supplementary Note 1) as described by equation (1). Note that thermal fluctuation, charge effect, interparticle interaction and gravitational force can be neglected owing to: the size of the GNR 21,22 , the interparticle distance and the fact that the pH value of the GNR solution is similar to the pK a of oleic acid, respectively.…”

Forced Desorption of Nanoparticles from an Oil–Water Interface

“…The spontaneous assembly of nanoparticles to form adsorbed monolayers at fluid-fluid interfaces has been exploited for stabilization of emulsions and foams [1][2][3][4][5] , for creating capsules and nanoporous membranes [6][7][8] , and has found application in phase-transfer catalysis 9,10 and enhanced oil recovery 11 .…”

Interfacial assembly of dendritic microcapsules with host–guest chemistry

“…More recently, the introduction of compartmentalization into such complex nano-or micro-scale systems is attracting considerable and wide-ranging interest for application in future delivery technologies [7][8][9] .…”

“…Supramolecular host-guest chemistry has been applied in the preparation of various self-assembled structures, including polymers 33,34 , micelles 35 , hydrogels 36,37 , colloids 38 and more recently by our group, microcapsules 39 . In this supramolecular system, CB [8] was exploited to crosslink a naphthol (Np) modified poly(acrylamide) copolymer and methyl viologen (MV) functionalized gold nanoparticles, forming a nanocomposite supramolecular skin around aqueous microdroplets. CB [8] is a macrocyclic host molecule that is capable of simultaneously encapsulating two guests within its cavity, forming a stable yet dynamic ternary complex 40,41 .…”