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A swell gel.


A swell gel

The quest for "smart" synthetic tissues, which can respond to changing conditions inside a human body, rests on the capacity of materials to react to their environment. In the case of artificial heart valves or muscle tissue, scientists want a material that can expand and contract quickly on demand. With this in mind, biomedical engineer Teruo Okano of Tokyo Women's Medical College and his coworkers have come up with a new spongelike material. In the March 16 Nature, the team reports that when this new polymer hydrogel absorbs and expels water, it swells and shrinks faster than other materials designed for the same purpose. This feat results from "tailoring the gel architecture at the molecular level."

The material has specially crafted, crosslinked molecules, or "comb-type grafts," they say. These molecules, vaguely resembling combs, have long polymer chains studded with small, toothlike side chains. The small side chains contain surfaces that help to expel water as the material shrinks. "Whereas similar gels lacking the grafted side chains can take more than a month to undergo full de- swelling, our materials collapse in about 20 minutes," the researchers state.
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Title Annotation:new 'smart' synthetic tissue, polymer hydrogel, quickly expands and contracts
Publication:Science News
Article Type:Brief Article
Date:Mar 25, 1995
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