ARBOR, Mich.---University of Michigan researchers
have discovered a way to self-assemble nanoparticles
into wires, sheets, shells and other unusual structures
using sticky patches that make the particles group
themselves together in programmed ways. This method
could be used to fabricate new materials and devices
computer simulation of model particles, Zhenli Zhang,
U-M research fellow in chemical engineering, and Sharon
Glotzer, U-M associate professor in chemical engineering,
studied the self-assembly of particles with sticky
molecular "patches" on their surfaces---discrete
interaction sites that cause particles to stick together
at just the right places to make the grouping organized.
The paper, "Self Assembly of Patchy Particles,"
appeared in Nano Letters this month.
results of the simulations showed that if surfaces
of particles could be patterned with patches of molecules,
they could make the particles assemble into different
shapes. The trick, according to the researchers, is
using patches that are strongly directional and attract
and repel specific parts of other particles, much
like proteins do.
finding is important because the biggest impediment
to developing nanotechnology is figuring out how to
build the tiny structures, which are only as big as
the smallest viruses. Because they are so small, nanodevices
will not be built by the traditional means of using
workers in factories or assembly lines. Rather, scientists
must develop ways to make the devices assemble by
themselves in precise ways for specific applications.
type of self-assembly happens constantly in nature,
but engineering it in the lab, so that eventually
scientists can predict their shapes and use the shapes
for specific applications, is another matter.
to the paper, many of the structures they were able
to predict with the model will prove useful in device
fabrication. For example, sheets of spheres with tunable
structures (an ordered arrangement of points that
can be changed) may serve as novel materials with
optical and mechanical properties.
chains, rings and twisted and staircase assemblies
could serve as basic structural units to further prepare
materials with more complex structures such as tubes,
helices and 3-D networks that could in turn, serve
as scaffolds or templates for assembly of electronic
or optical components, or as channels for transport
of liquids or molecules.
more information about Glotzer's group, visit http://www.engin.umich.edu/dept/che/research/glotzer/index.html
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