Ana Vesperinas

Self-assembly of light-sensitive surfactants

This review covers recent advances with an intriguing class of functionalised light-sensitive surfactants. The main chemical classes are described, and the photo-responses in interfacial and aggregation systems are discussed.

Photorecovery of nanoparticles from an organic solvent.

Commercial silica nanoparticles were dispersed in toluene, stabilized by a mixture of sodium bis(2-ethylhexyl)sulfosuccinate (AOT) and a photolyzable anionic surfactant sodium hexylphenylazosulfonate (C6PAS). Selective photolysis of the interfacial C6PAS component induces colloid instability, resulting in flocculation and eventual phase separation of the silica nanoparticles. UV-vis spectroscopy was used to follow the photochemical breakdown of C6PAS; diffusion coefficient measurements by dynamic light scattering were employed to monitor the photoinduced flocculation; and silica contents in the toluene, before and after UV light irradiation, were determined gravimetrically. The results show that light can be used to trigger separation and recovery of nanoparticles stabilized by photolabile interfacial layers.

Recycling nanocatalysts by tuning solvent quality

Catalytic surfactant stabilized gold-containing nanoparticles have been recovered by a new isothermal low-energy approach, by controlled and reversible changes in colloid stability based on fine-tuning of solvent quality. Once recovered, the nanoparticles can be re-dispersed in the solvent, or indeed dispersed into a different solvent. The morphology of the nanoparticles is not significantly affected by the recovery process and they can be used and reused as oxidation catalysts.

Stabilization of CeO(2) nanoparticles in a CO(2) rich solvent

Here it is shown that the chemical nature of outer organic surfactant layers, used to stabilize inorganic nanoparticles (NPs), is a key factor controlling solubility in a mixed liquid CO(2)-heptane (10% vol) solvent.

Recovery and Reuse of Nanoparticles by Tuning Solvent Quality

Nanoparticles Are Forever: An isothermal low-energy approach permits recovery of nanoparticles for reuse by tuning solvent quality. The recovered and redispersed nanoparticles retain their morphology and chemical reactivity for recycle and reuse. The method, shown here to be effective in the application of nanoparticles as catalysts, will have a wide and general applicability.