Dutch researchers have discovered a quick and inexpensive method to make polymers water repellant. The process uses a special high-speed laser, called 'fematosecond laser', which shot short bursts of high-energy light at one-millionth of a billionth of a second onto a steel surface. At that high speed, the laser has very little time to melt the metal or produce craters.
With one burst, the fematosecond laser vaporizes a tiny spot about half the diameter of a human hair, and some billionth of a meter deep. By applying more pulses, one can create deeper holes and by careful arrangement of millions of laser bursts, it is possible to write the bumpy structure. During vaporization, tiny structures in the metal begin to grow. These substructures add a second roughness, which makes the surface super water repellent. This technique can easily be applied during injection moulding process. During process, while forcing molten polymer into the mould under high pressure, the molded product becomes water repellant.
Other developments in water repellant polymers include:
A team from Virginia Commonwealth University has developed a novel material that becomes water repellent when wet, by creating an enigmatic polymer that is hydrophilic, or water loving, when dry, and hydrophobic, or water resistant, when wet. This material is a leap forward for advances in engineering, medicine and diagnostics. This innovation was accidently made when the team was working to create antimicrobial coatings by incorporating a molecule called hydantoin into fluorine-containing polymer chains. It was observed that the water drops were spreading, wetting the surface. The change was caused by a rearrangement of the polymer side chain, which exposed the hydrophobic, fluorine-containing groups to the surface and made them repel water.
A team at North Carolina State University has forced molecules to create an almost impenetrable layer by bonding them chemically to a polymer material that has been stretched, then released again to regain its original shape. The molecules are jammed into a tight-knit, non-stick layer that could one day coat everything from frying pans to disk drives, medical implants to airplanes. Such surfaces would be highly water-repellent and nearly frictionless, and might reduce the need for many lubricants. Potential applications could include:
Improving the biocompatibility of medical implants or prostheses by reducing friction and inhibiting the interaction with surrounding cells
Coating airplanes with a water repellent that could eliminate the need for de-icing
Covering adjacent disk drive components with a substance slippery enough to prevent scratching.
Researchers at General Electric have come up with a way to process a common polymer so that it repels fluid so effectively that even honey rolls right off it. The resulting property is called superhydrophobicity. The discovery could allow everything from new, easy-to-clean building materials to cheap diagnostic devices with plastic microfluidic channels. GE estimates it will take at least five years to commercialize the technology, once all manufacturing issues are resolved.