Embargoed until 2 p.m. EST
NSF PR 01-23 - April 5, 2001
Media contact:
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Amber Jones
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(703) 292-8070
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aljones@nsf.gov
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Program contact:
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Andrew Lovinger
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(703) 292-4933
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alovinger@nsf.gov
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This material is available primarily
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Polymer Full of Holes -- But Good for Photonics?
Simple process makes good use of bubbles
Scientists developing photonic devices for optical
and electronic applications may get a boost from a
new process for "cutting" 3-D arrays of holes in a
polymer material.
Mohan Srinivasarao of the Georgia Institute of Technology
found a way to create an orderly pattern of air bubbles
throughout a polymer film using a simple solvent.
By controlling the polymer, solvent, humidity and
flow of air across the polymer, he triggers the condensation
of tiny uniform water droplets. The droplets sink
into the polymer film. The process repeats itself
on its own until the film is filled with a three dimensional
array of water bubbles. When the solvent and water
evaporate, they leave behind a polymer scaffold with
a lattice of equal-sized air bubbles.
"The beauty of this process lies in its simplicity,"
said Andrew Lovinger, director of the polymers program
at the National Science Foundation (NSF), which funded
the work.
"You just let the solvent evaporate at room temperature
and in a few seconds you get these beautiful honeycombed
polymer films."
"This represents an easy way of making materials with
the regular structure needed for optical and photonic
applications," said Srinivasarao. "This is completely
a self-assembly process." He reports on the results
in the April 6 issue of Science.
If the process is shown to be usable in developing
photonic bandgaps or photonic crystals, it could contribute
to the development of optical switches and the ability
to direct or "steer" light beams, just as electrical
switches and conducting materials control and direct
electrical current. Potential applications include
lasers, antennas, millimeter wave devices and solar
cells.
Srinivasarao, a physical polymer chemist in Georgia
Tech's textiles and fiber engineering department,
is an NSF CAREER awardee. The CAREER program provides
financial support to young investigators during the
early years of their faculty positions. According
to Lovinger, the program emphasizes not only first-rate
research but also "educational commitment and innovation."
As part of his educational outreach, Srinivasarao organized
several workshops sponsored by NSF and Exxon Corp.
for high-school science teachers on "Polymers in Everyday
Life."
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