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Team Combines Coatings to Produce Water- and Microbe-Resistant
Fabric
CAMBRIDGE, Mass., October 1, 2003 - Researchers at the ISN
have recently demonstrated a technique for combining two polymeric
coatings to create fabrics that are both water-repellent and
bactericidal. The combination of the two coatings, which were
initially developed in two separate laboratories, shows significant
potential for use on soldier uniforms and other equipment.
Researchers working with Professor
Karen Gleason of the Department of Chemical Engineering
have used a process called hot filament chemical vapor deposition
(HFCVD) to deposit nanolayers of polytetrafluoroethylene (PTFE,
also known as Teflon®). They have used the process to
waterproof ordinary cotton T-shirt fabric, which retains its
breathability and is indistinguishable in look and feel from
untreated fabric.
Unlike many commercially available waterproofing processes,
the HFCVD process deposits the coating from the vapor phase,
offering the potential to coat materials that cannot be immersed
in a solution. “For example, the U.S. Army is interested
in waterproofing bullet-resistant panels made of Kevlar®,”
Gleason said. “Because of the chemical characteristics
of Kevlar®, some of these other solution-based techniques
wouldn’t necessarily even wet it.”
Concurrently, researchers working with Prof.
Alex Klibanov of the Department of Chemistry have developed
coatings of N-alkylated poly(4-vinylpyridines) and polyethylenimines
(PEIs) that render glass, plastic and various textile surfaces
high microbicidal. The coatings have been shown to kill various
bacteria (like staphylococcus and E. coli)
and fungi (like candida albicans) efficiently on
contact.
Under the auspices of the ISN, the two faculty members came
together to study how the two coatings might be combined to
create fabrics and other surfaces that are both water-repellent
and bactericidal. Early work has demonstrated that cotton
fabric coated first with N-alkyl-PEI followed by chemical
vapor deposition of a fluorocarbon polymer (similar to PTFE)
shows excellent water repellency and bactericidal efficiency
of up to 92%. The coatings retained their effectiveness even
after a 30-minute washing in cold water containing 10% commercial
liquid detergent with vigorous stirring.
Gleason’s waterproofing technique is also capable of
coating unusual geometries, like fine wires, on which traditional
PTFE deposition processes—involving baking a thick layer
of powder—do not work. Gleason also points out that
the HFCVD process can go beyond the exterior surface of a
material to coat interior cavities, such as those in a porous
substance like foam.
“If we coat a piece of one-inch thick foam and we cut
the foam open, it’s hydrophobic, or water-repellent,
in the middle,” she says. Her group is currently studying
how the process might be used to provide multi-layer water-repellency
to a soldier’s nylon poncho liner. The combined coatings
are being studied for use on soldier clothing, bedding, and
equipment.
Profs. Gleason and Klibanov recently published a paper on
their joint work to Biotechnology Letters Vol. 25(19),
pp. 1661-1665. Coauthors included Dr. Jian Lin, Dr. Shashi
K. Murthy, and Mr. Bradley D. Olsen.
Contact:
Franklin Hadley
617-324-6413
fhadley@mit.edu
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