INTELLIGENT GELS

作者：RON DAGANI · 发表于：Chemical & Engineering News · 年份：1997 · DOI：10.1021/cen-v075n023.p026 · 被引用次数：39 · 研究领域：Physics and Engineering Research Articles、Advanced Numerical Analysis Techniques、Aerogels and thermal insulation

“It was very puzzling," says Toyoichi Tanaka, referring to a discovery he made shortly after joining the physics faculty at Massachusetts Institute of Technology in 1975. He and his coworkers were studying gels, cross-linked polymer networks that can absorb enough solvent to swell. They discovered that by cooling a clear polyacrylamide gel, they could make it cloud up and eventually become opaque. Warming the gel restored its clarity. That was not the kind of behavior Tanaka had been expecting. What he had stumbled upon was a phase transition in a polymer network—a phenomenon akin to the interconversion of the liquid and vapor phases of water at the critical point. Some of Tanaka's colleagues, however, were skeptical of his explanation because the gel transition occurred at about -20 °C. They thought his observations might be due to the formation of tiny ice crystals in the gel. To prove them wrong, Tanaka embarked on another experiment, one ...