Caneba: Developing an All-Purpose Polymer
Gerard Caneba hands out two plastic baggies of what look like polystyrene
muffins in aluminum pans. One set is hard and flat, as if someone forgot
to add the baking soda. The others are airy, fluffy balls of . . . what?
Caneba, an associate professor of chemical engineering, picks up one
of the big puffy ones. "I like this," he says, turning it around
in his fingers. "It's amazing to see what it does when it's blown
up in a vacuum."
So, what is it, besides a cupcake-size version of packing peanuts?
Caneba starts a list: it's sticky but can become slippery; it's a surfactant
and a foam. Plus, it can be made biodegradable.
At some point, there might be a shorter name for the stuff. But for now,
this patent-pending copolymer is known by its two parts; vinyl acetate-acrylic
acid. Its dual nature is what makes it so versatile. "We've developed
a unique and efficient process to distribute the two chemicals differently
along the chain or neutralize the acid with a variety of bases and have
different properties," Caneba said.
"We've produced some really neat new materials."
The surfactant, or detergent, form of the copolymer dissolves into particles
up to 200 times larger than regular detergents. "It can disperse
big, toxic organic compounds such as PCBs much more efficiently,"
which could make it particularly useful in mopping up spills. And, being
biodegradable, it wouldn't be as polluting.
The copolymer has been shown to have promise in oil recovery. "Usually,
petroleum is trapped within the pores of the rocks inside an oil well,"
Caneba said. "Billions of barrels of oil is unrecovered from existing
wells here in the continental US alone."
Surfactants are used to improve oil recovery, and it looks like vinyl
acetate-acrylic acid may outperform current products--by up to 400 percent--at
a much lower cost.
You can also rearrange the copolymer to produce a coating that's slick
on one side and sticky on the other. "That lets you make real low-friction
surfaces," Caneba said.
And another form of vinyl acetate-acrylic acid could be used to create
composites, binding wood and plastic together. "It seems to have
an affinity for lots of natural materials," Caneba said. "It's
inexpensive, it performs well and its environmentally responsible."
It even has an unusual property that could give it a role in constructing
micro- or nano-electrical mechanical systems.
The copolymers naturally form tight coils and don't tangle up with each
other. "They stay separate for a long time; it's amazing," Caneba
said.
At Argonne National Laboratory, where Caneba was a summer research fellow,
he and his colleagues were able to show through X-ray scattering methods
that the primary structures formed during chemical reactions are very
stable, even at nano-scales.
"When you get to that level, quantum mechanics kicks in and people
don't know what's going on, especially in a chemical reaction," Caneba
noted. "But this reaction is very well-controlled, so it might be
useful in MEMS or even NEMS production."
Because it can form such small, stable structures, the copolymer might
be used to make super-small filters, used in bioengineering and pharmaceuticals.
"Or it might be used as a grid for cells to grow on," Caneba
muses. "When the primary structures are that small, you can do really
fine patterning."
At this point, he and his co-workers are using X-ray lithography, a technique
used in microelectronics, to produce a very uniform, square grid pattern
from a similar material that's biologically compatible, opening up possibilities
in medicine and biological engineering.
"I'm sure other people would have other ideas," he adds. "It's
quite exciting."
03/01/02
