At Albert Poortinga

Microcapsules from Self-Assembled Colloidal Particles Using Aqueous Phase-Separated Polymer Solutions

We report a new way of producing microcapsules consisting of a shell of aggregated colloids (also referred to as colloidosomes) using aqueous phase-separated polymer solutions (water-in-water emulsions) as a template. The extremely low interfacial tension of the template allows the production of reversible colloidosomes that spontaneously disintegrate depending on environmental conditions, making them ideal for controlled release purposes. Also, colloidosomes can have an elongated shape such that they may be used as microfluidic membranes or artificial arteries. Because the method described here does not use any organic solvents, it enables the use of sensitive materials such as cells and proteins.

Generation of antibubbles from core-shell double emulsion templates produced by microfluidics.

We report the preparation of antibubbles by microfluidic methods. More specifically, we demonstrate a two-step approach, wherein a monodisperse water-in-oil-in-water (W/O/W) emulsion of core-shell construction is first generated via microfluidics and freeze-dried thereafter to yield, upon subsequent reconstitution, an aqueous dispersion of antibubbles. Stable antibubbles are attained by stabilization of the air-water interfaces through a combination of adsorbed particles and polymeric surfactant. The antibubbles strongly resemble the double emulsion templates from which they were formed. When triggered to release, antibubbles show complete release of their cores within about 100 ms.

Long-Lived Antibubbles: Stable Antibubbles through Pickering Stabilization

Antibubbles, which are liquid droplets surrounded by a thin shell of gas in a liquid phase, have several promising applications, among which is encapsulation. A major hurdle toward these applications has hitherto been the inherent instability of antibubbles, leading to lifetimes of at most minutes. Here we show the production of antibubbles with a lifetime of at least tens of hours, with their stability stemming from the adsorption of colloidal particles at gas-water interfaces. Antibubbles were produced by coating aqueous droplets with hydrophobic colloidal particles, gelling the droplets, and then dropping them into an aqueous colloidal suspension. This resulted in the formation of antibubbles with a long lifetime, also after the melting of the gel.