Researchers Create "Smart," Switchable Surfaces
Molecular coating could aid nanoscale assembly, microfuidics
Materials researchers at Iowa State University, working in part under a grant from the National Science Foundation, have demonstrated a novel coating that makes surfaces “smart”—meaning the surfaces can be switched back and forth between glassy-slick and rubbery on a scale of nanometers, the size of just a few molecules.
Possible applications include the directed assembly of inorganic nanoparticles, proteins, and nanotubes, and the ultra-precise control of liquids flowing through microfluidic devices that are finding their way into biomedical research and clinical diagnostics.
The new coating is a single layer of Y-shaped “brush” molecules, according to principal investigators Vladimir V. Tsukruk and Eugene R. Zubarev, lead authors on a report of the work in the September 16 issue of the journal Langmuir.
Each molecule attaches to the surface at the base of the Y, which forms a kind of handle for the brush, and extends two long arms outward to form the bristles. The coating can be switched because one arm is a polymer that is hydrophilic, or attracted to water, while the other is a polymer that is hydrophobic, or repelled by water.
Thus, say the researchers, when the coated surface is exposed to water, the molecules collapse into a series of mounds about 8 nanometers wide, with the hydrophilic arms on top shielding the hydrophobic arms inside. Conversely, when the surface is treated with an organic solvent such as toluene, the surface spontaneously reorganizes itself into mounds that have the hydrophobic arms on top.
Not surprisingly, the two states are very different when it comes to properties such as stickiness and the ability to become “wet.”
In future work, the Iowa State team hopes to coax the mounds into an ordered pattern, instead of the current random scatter, which may allow the researchers to make surfaces that are lubricating in one direction and sticky in others.
NSF Media contact: M. Mitchell Waldrop, (703) 292-7752, email@example.com
NSF Program manager: Andrew Lovinger, (703) 292-4933, firstname.lastname@example.org
Principal Investigators: Vladimir Tsukruk, (515) 294-6904, Vladimir@iastate.edu
Eugene R. Zubarev, (515) 294-9465, email@example.com
All news from this category: Materials Sciences
Materials management deals with the research, development, manufacturing and processing of raw and industrial materials. Key aspects here are biological and medical issues, which play an increasingly important role in this field.
innovations-report offers in-depth articles related to the development and application of materials and the structure and properties of new materials.
A little friction goes a long way toward stronger nanotube fibers
Rice model may lead to better materials for aerospace, automotive, medical applications. Carbon nanotube fibers are not nearly as strong as the nanotubes they contain, but Rice University researchers are…
Light-induced twisting of Weyl nodes switches on giant electron current
Scientists at the U.S. Department of Energy’s Ames Laboratory and collaborators at Brookhaven National Laboratory and the University of Alabama at Birmingham have discovered a new light-induced switch that twists…
Acidification impedes shell development of plankton off the US West Coast
Shelled pteropods, microscopic free-swimming sea snails, are widely regarded as indicators for ocean acidification because research has shown that their fragile shells are vulnerable to increasing ocean acidity. A new…