The interfacial structure of nano- and micron-sized oil and water droplets stabilized with SDS and Span80.

In this work, we provide a comparison between the stability and the interfacial structure of micrometer-sized and nanometer-sized droplets by employing a multi-instrumental approach comprised of the surface-sensitive technique of sum frequency scattering as well as dynamic light scattering and microscopy. We monitor the stability of oil-in-water and water-in-oil emulsions and the structure of surfactants at the oil/water nano-interface, when stabilized with an oil-soluble neutral surfactant (Span80), a water-soluble anionic surfactant (sodium dodecyl sulfate, SDS), or with a combination of the two. Micron-sized droplets are found to be stabilized only when a surfactant soluble in the continuous phase is present in the system, in agreement with what is traditionally observed empirically.

Bioinspired Viscoelastic Capsules: Delivery Vehicles and Beyond.

Microcapsules are often used as individually dispersed carriers of active ingredients to prolong their shelf life or to protect premature reactions with substances contained in the surrounding. This study goes beyond this application and employs microcapsules as principal building blocks of macroscopic 3D materials with well-defined granular structures. To achieve this goal and inspired by nature, capsules are fabricated from block-copolymer surfactants that are functionalized with catechols, a metal-coordinating motive.

Cross-talk between emulsion drops: how are hydrophilic reagents transported across oil phases?

Emulsion drops are frequently used as vessels, for example, to conduct biochemical reactions in small volumes or to perform screening assays at high throughputs while consuming minimal sample volumes. These applications typically require drops that do not allow exchange of reagents such that no cross-contamination occurs. Unfortunately, in many cases, reagents are exchanged between emulsion drops even if they have a low solubility in the surrounding phase, resulting in cross-contaminations.