Splashy route to small capsules

Abstract

A new high-speed encapsulation method ensnares droplets in a thin polymer film. The technique, developed by Narayanan Menon, Deepak Kumar, and Thomas P. Russell of the University of Massachusetts, Amherst, along with Joseph D. Paulsen of Syracuse University, could create a new type of tiny chemical reaction flask or be used for targeted delivery of tiny amounts of liquid cargo. In conventional liquid-encapsulation methods, a fluid layer of surfactants or particles forms a shell around the contents. The new technique involves dropping a hydrophobic liquid onto a solid, ultrathin polymer disk floating on an aqueous solution. The oil droplet’s impact pushes the disk, which is just 46–372 nm thick, down into the aqueous solution, coaxing the polymer to wrap around the oil and form a tiny bag—a process that takes less than half a second (Science 2018, DOI: 10.1126/science.aao1290). “All the droplet has to do is punch the polymer sheet