On the behaviour of nanoparticles in oil-in-water emulsions with different surfactants

Abstract

The distribution of narrowly dispersed gold nanoparticles in hexane-in-water emulsions was studied for different surfactants. Good surfactants such as SDS and Triton X-100 block the oil-water interfaces and confine particles in the droplet. Other surfactants (Tween 85 and Span 20) form synergistic mixtures with the nanoparticles at the interfaces that lower the surface tension more than any component. Supraparticles with fully defined particle distribution form in the droplets only for surfactants that block the interface. Other surfactants promote the formation of fcc agglomerates. Nanoparticles in emulsions behave markedly different from microparticles-their structure formation is governed by free energy minimization, while microparticles are dominated by kinetics.

A Translucent Nanocomposite with Liquid Inclusions of a Responsive Nanoparticle Dispersion

“…This processing time provided a good compromise between fragmentation and recombination due to agitation in order to achieve the desired average droplet size (see the Supporting Information). We added Triton X‐165 as a surfactant to increase the stability of the emulsion and to prevent the particles from segregating to the liquid–liquid interface …”

“…Particularly strong is the effect on coupled plasmonic particles that change color and reflectivity depending on their distance and electronic coupling, which has been exploited to enhance contrast in optical coherence tomography or dark‐field microscopy, for example. One way to control the particle arrangement is their assembly and encapsulation in liquid droplets prior to composite formation . Particles inside droplets or emulsions arrange into supraparticles as the solvent evaporates, a process that is extensively used to arrange particles in food technology and cosmetic industry…”

Green and stable processing of organic light-emitting diodes from aqueous nanodispersions

“…However, we refrain from doing so due to the fact that these are significantly less effective in stabilizing the emulsion droplets and the final solid particles. 29 After emulsification and solvent evaporation, we removed the excess of SDS by extensive dialysis 30 (see Experimental section). Optimal PLED operation would require removing as much SDS as possible, i.e.…”

Pressure-controlled formation of crystalline, Janus, and core–shell supraparticles

“…Alkanethiol-coated gold nanoparticles with 6 nm diameter do not segregate to hexane-water interfaces with Triton X-100. 16 Likewise, interfacial tension measurements that we performed indicated no segregation for any of the surfactants that we used here. We believe that the formation of supraparticles is dominated by nucleation: different supraparticles form when selfassembly starts at different particle concentrations.…”

“…The arithmetic mean and the standard deviation were calculated from a minimum of 200 calculated tension values obtained in the equilibrium state. 16 The measurements were performed at 25°C and 50°C.…”