Clay reduces permeability of biomedic...( Chicago A compound used in cosmetics a...),Health

"The polymers used for various parts of artificial heart devices are somewhat permeable to air and water," says Dr. James Runt, professor of polymer science. "We decided to look at two methods for decreasing permeability a chemical method and a nanocomposites approach." The methods tried used a poly (urethane urea) polymer similar to that already used for the pumping chamber, cannula and compliance chamber in the Arrow LionHeart, a left ventricular device developed by Arrow International and Penn State, and earlier heart devices developed at Penn State. In the current devices, air inside the compliance chamber helps in the pumping, but over time, the air seeps through the polymer wall of the chamber into the body and dissipates. The air has to be periodically replaced. The polymer used is also permeable to water, and care must be taken so that the electronics in artificial heart devices remain dry.

The chemical method took the standard polymer and attached polyisobutylene chains to it to form a comb like structure. The hope was that these combs would create a barrier for air and water. The researchers incorporated up to35 percent by volume polyisobutylene into the poly (urethane urea). The resulting polymer had good mechanical properties, but has not been tested for fatigue resistance.

"Creating these copolymers was relatively difficult and only achieved a factor of two improvement in permeability over the original polymer," Runt told attendees at the 222nd American Chemical Society annual meeting in Chicago today (Aug. 26). "It involved quite a bit of work with only a modest return."

Turning to an alternative solution to the problem, the researchers looked at a commercially available silicate clay, cloisite 15A, produced by Southern Clay Produ
'"/>

Contact: A'ndrea Elyse Messer
aem1@psu.edu
814-865-9481
Penn State
26-Aug-2001