A new discovery by researchers in Michigan could lead to more environmentally friendly paints, better oil dispersants and a host of other innovations.
Engineers at the University of Michigan have developed a process that can sprout microscopic spikes on almost any type of particle. They call these "hedgehog particles" and their research is detailed in the latest issue of Nature.
By modifying oily, or hydrophobic, particles, the new process enables them to disperse easily in water. Similarly, water-soluble, or hydrophilic, particles, can be modified so that they dissolve in oil or other oily chemicals.
So how does it work?
The team created hedgehog particles by growing zinc oxide spikes on polystyrene microbeads, but the process can be performed on virtually any type of particle and the spikes can be made out of materials other than zinc oxide.
The tiny spikes make the particles repel each other more and attract each other less. The spikes also dramatically reduce the particles' surface area, helping them to diffuse more easily, the university reported.
These particles have potential applications in paints and coatings, where toxic volatile organic compounds (VOCs) like toluene are currently used to dissolve pigment. It's thought that pigments made from hedgehog particles could be dissolved in non-toxic carriers like water, resulting in fewer VOC emissions.
"VOC solvents are toxic, they're flammable, they're expensive to handle and dispose of safely," said Nicholas Kotov, the Joseph B. and Florence V. Cejka Professor of Engineering. "So if you can avoid using them, there's significant cost savings in addition to environmental benefits."
Kotov believes that, although some low- and no-VOC coatings are already available, hedgehog particles could provide a simpler, more versatile and less expensive way to manufacture them.
Further applications of hedgehog particles might include improved oil dispersants that help in the cleanup of oil spills, and better ways to deliver non-water-soluble prescription medications.
"Any time you need to dissolve an oily particle in water, there's a potential application for hedgehog particles," Kotov said. "It's really just a matter of finding the right commercial partners. We're only just beginning to explore the uses for these particles, and I think we're going to see a lot of applications in the future."