Grease gone: A five-micrometer drop of a solvent bounces off a
surface coated with the new material. German researchers armed
with smoking candles have come up with a cheap and easy way to
coat surfaces so that oil droplets bounce or roll right off. The
advance could eventually lead to eyeglass coatings and tablet
computer screens that can evade the mark of even the greasiest
fingerprints. Making surfaces able to repel fluids—whether
water- or oil-based—is also important for industrial and
biomedical applications. But it’s harder to make a surface that
repels oil or organic solvents as opposed to water because oil
has a far lower surface tension than water. What’s required is a
very specific type of surface roughness—akin to the branches of
a budding tree—that achieves oil-repellency. This has been
understood for some time, but it has been difficult to fabricate
such a texture. Earlier work at MIT and elsewhere involved
complex nanolithographic techniques. Researchers at the Max
Planck Institute for Polymer R