Researchers engineer new polymers to change their stiffness and strength when exposed ...( CLEVELAND -- An interdisciplinary t...)

CLEVELAND -- An interdisciplinary team of researchers from the departments of macromolecular science and engineering and biomedical engineering at the Case School of Engineering and the Louis Stokes Cleveland Department of Veterans Affairs Medical Center has published ground-breaking work on a new type of polymer that displays chemoresponsive mechanic adaptability -- meaning the polymer can change from hard to soft plastic and vice versa in seconds when exposed to liquid -- in the March 7, 2008, issue of Science, one of the world's most prestigious scholarly journals covering all aspects of science.

Jeffrey R. Capadona, associate investigator at the VA's Advanced Platform Technology (APT) Center, graduate student Kadhiravan Shanmuganathan, and Case Western Reserve University professors and APT investigators Dustin Tyler (biomedical engineering), Stuart Rowan (macromolecular science) and Christoph Weder (macromolecular science) have unveiled a radically new approach for developing polymer nanocomposites which alter their mechanical properties when exposed to certain chemical stimuli.

"We can engineer these new polymers to change their mechanical properties -- in particular stiffness and strength -- in a programmed fashion when exposed to a specific chemical," says Weder, one of the senior authors of the paper.

"The materials on which we reported in Science were designed to change from a hard plastic -- think of a CD case -- to a soft rubber when brought in contact with water," adds Rowan, who has been Weder's partner on the project for almost six years.

"Our new materials were tailored to respond specifically to water and to exhibit minimal swelling, so they don't soak up water like a sponge," saud Shanmuganathan.

In their new approach, the team used a biomimetic approach -- or mimicking biology -- copying nature's design found in the skin of sea cucumbers.

"These creatures can reversibly and quickly change the stiffness of the
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