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Chemist Victoria
Finkenstadt displays different samples of electroactive bioplastics developed
in her laboratory at the National Center for Agricultural Utilization Research.
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Biobased Plastic Flexes its Muscle
By Jan Suszkiw
December 1, 2005
Electroactive polymersplastics that expand or contract when
stimulated by electricitycan now be made from plants rather than
petrochemicals, according to Agricultural Research Service (ARS) scientists in Peoria, Ill.
There is now significant interest in the possible use of electroactive
polymers in many industrial and biomedical applications, from light-emitting
diodes and controlled-release devices to artificial muscles and environmental
sensors. The material is typically petroleum-based, but ARS researchers
Victoria
Finkenstadt and
J.L.
Willett showed that plant polysaccharides like starch can work just as
well.
Use of the polysaccharides in certain types of conductive polymers
could leapfrog some of the pitfalls associated with using petroleum feedstocks,
such as U.S. reliance on foreign suppliers, according to Finkenstadt, a
chemist, and Willett, a supervisory chemical engineer with ARS'
National
Center for Agricultural Utilization Research in Peoria.
There, in the
Plant
Polymer Research Unit, the scientists created biobased polymers that bend
and contract slightly when pulsed with electricity. In nature, many
polysaccharides are natural insulators, meaning they obstruct the flow of
electricity. However, the Peoria team devised a process for overcoming this so
that the biopolymers conduct electricity at levels similar to synthetic
products.
Cornstarch is an ideal starter material because it is
inexpensiveabout 20 cents a poundand plentiful. In 2004, U.S.
farmers planted nearly 81 million acres of corn and harvested approximately 12
billion bushels. (One bushel yields an average of 32 pounds of cornstarch.) By
comparison, one of the synthetic polymers the scientists used, polyaniline
emeraldine, costs $58 a gram.
One potential use for the biopolymers is in recharging of lithium
batteries. Petroleum-based gels are now used, but Finkenstadt wants to find out
whether the biobased polymers could shorten the recharging time, or hold the
charge longer.
Read
more about the work in the December 2005 issue of Agricultural
Research magazine.
ARS is the U.S. Department of
Agriculture's chief scientific research agency.