Cleaning oily smears from kitchen countertops, mirrors, garage floors, and
other surfaces with plain water - rather than strong detergents or smelly solvents
- may seem like pure fantasy. But scientists in Indiana today describe what
they believe to be a simple and effective state-of-the-art oil stain remover.
They have developed a new coating for glass, plastics, and a range of other
materials that would enable consumers to wipe away those pesky oils with plain
water.
 | | To create easy-to-clean surfaces, scientists have developed coatings for use on an array of materials, including fabrics, glass, concrete and windshields. Credit: Aldridged, Dreamstime.com |
Their report at the 238th National Meeting of the American
Chemical Society (ACS) points out that the same coatings can be added to
common window cleaning sprays and used to prevent bathroom mirrors, automobile
windshields and other surfaces from fogging up.
"You add water, and the oil just comes right off like magic," said
Jeffrey Youngblood, Ph.D., lead researcher on the project. "These are eco-friendly
coatings - environmentally 'green' in the sense that they eliminate the
need for harsh detergents and solvents in settings ranging from home kitchens
to industrial machine shops that must contend with heavy oil spills."
The materials could be used in a range of consumer and industrial products,
Youngblood said. They include household cleaners, easy-to-clean paints, water
filters that separate water from oil, sealants for concrete floors and walls
that repel oil in home garages and auto repair shops. In addition, anti-fog
coatings could be used on windshields or eyewear, including everyday lenses
and fog-free scuba masks.
The eco-friendly plastics could reduce the need for detergents containing phosphates.
"We put out tons of detergents and phosphates each year," said Youngblood,
adding that the polymer materials also could reduce the use of detergents for
laundering clothes. This would cut down on the release of phosphates, which
wash into lakes and streams and stimulate growth of algae, depleting oxygen
supplies in ways that cause fish kills in waterways and make swimming unsafe
for humans.
"The idea is to use these polymers to clean in situations where it's inconvenient
to apply soap or anywhere you would need to have oil cleaned off easily,"
said Youngblood, a materials engineer at Purdue University in West Lafayette,
Ind. "Oil fouling is always a problem. A lot of people overlook the fact
that pure water will generally not remove oil from a surface, but using this
product transforms water into a super detergent."
Youngblood's group spent years in an effort to develop substances with the
goal of making a surface that would repel oil more than water. Once successful,
their framework for self-cleaning plastics was in place. "With these materials,
if you stuck an oil droplet on them you could completely remove it with water.
You could basically do soap-free rinsing."
These polymer coatings - about 20,000 times thinner than the width of
a human hair - were highly sensitive to water and would break to the touch.
Youngblood has built upon these materials to make a new family of ready-to-use
polymers that can be easily applied to a variety of surfaces.
They have a bottom layer of polyethylene glycol, which attracts water, and
an upper layer of a Teflon-like molecule that prevents the passage of oil. The
result is a surface that holds a film of water while repelling oil. "Our
work is a big step forward toward useable materials as either additives or coatings,"
he said, "and few others are working in this area. Most research on self-cleaning
is done with different surfaces."
Youngblood is currently evaluating self-cleaning and anti-fog capabilities
for polymers on different kinds of metals and ceramics. Preliminary tests on
the lifetime of anti-fog coatings are especially encouraging. "We have
stored these on shelves and use it months afterwards, and we haven't noticed
a decrease in performance," he said. "We feel that we can make all
our self-cleaning plastics commercially available within a few years."
Posted August 16th, 2009
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