Borrowing from one of nature's most __________-repellent __________ , the leaf of the lotus plant, scientists have developed a simple, inexpensive way to create synthetic coatings with exceptional anti-wetting properties. Such coatings can help to reduce drag on ship hulls, stain- and __________-proof fabrics and improve separation processes in mining industries.
The raincoats we wear to stay dry during stormy weather work because a special coating on the fabric prevents __________ from soaking through the fibers. To determine how __________-repellent a given __________ is, scientists look at the shape of a __________ droplet on that __________. More precisely, they study the so-called contact : the __________ formed by the intersection of imaginary lines drawn tangent to the droplet __________ and the fabric __________. The more hydrophobic a substance is, the higher the contact __________ and the more spherical the __________ bead. Human skin, for example, is a hydrophobic __________ with a contact __________ of about 90 degrees. Bird feathers and lotus leaves are considered superhydrophobic, with contact __________ of 150 and 170 degrees, respectively.

The __________ of a lotus leaf is not perfectly smooth. Rather it has a porous texture much like that of a sponge or bird's nest, albeit on a micrometer scale. The air trapped in the crevices prevents __________ from adhering to the solid. Researchers led by H. Yildirim Erbil of Kocaeli University in Turkey re-created this naturally superhydrophobic __________ in their laboratory by first dissolving polypropylene, a commercially available simple plastic, in a solvent. They then added a precipitating agent and applied the solution to a glass slide. After evaporating the solvent mixture in a vacuum oven, they had a highly porous gel coating with a contact __________ of 160 degrees and __________-repelling capabilities comparable with those of the lotus leaf. (The investigators applied their coating to other substrates, too - aluminum foil and stainless steel, among them - and achieved similar results.)

Superhydrophobic coatings already in use often require expensive materials and time-intensive application procedures. The new findings, published in the current issue of the journal Science, show that the __________ repellency of polypropylene can be significantly increased through an easy processing step. The researchers thank the lotus flower: "We mimicked nature to find a simple solution for a difficult technological problem."