Environmental remediation has always been a pressing issue because of the multiple instances of devastating oil spills such as the major spill over the gulf coast.

Martin Pumera and co-workers, Nanyang Technological University, Singapore, use self-propelled biocompatible capsules of millimetre dimensions loaded with various surfactants containing negative, positive and neutral charge (sodiaum dodecyl sulphate (SDS), cetyl trimethylammonium bromide, and Tween 20) and compared their influence upon movement of oil droplets (see figure for mechanism of motion of the oil droplet where γ is surface tension and F is pulling force). With increasing concentration of surfactants the velocity of the repulsed oil droplet increases monotonically.

The increase is most dramatic for SDS. Their findings will have profound impact on the potential applications of such millimetre capsules for environmental clean-up applications.

• Surfactant Capsules Propel Interfacial Oil Droplets: An Environmental Cleanup Strategy,
  Tzu Hui Seah, Guanjia Zhao, Martin Pumera,
  ChemPlusChem 2013.
  DOI: 10.1002/cplu.201300011