SHAPE-MEMORY GELS MADE BY THE MODULATED GEL TECHNOLOGY

Shape memory gels based on interpenetrating only part of one gel netwo rk with another gel network have been synthesized. These gels consist of two parts: a control element, which is responsive to a designated e nvironmental stimulus, and a nonresponsive substrate element. By desig ning the pattern in the gelation process, a variety of shapes are obta ined including ''spiral,'' ''square,'' ''fish,'' ''numbers,'' ''alphab ets,'' and ''tube.'' The change between two different shapes can be co ntrolled by external stimuli such as temperature and is reversible. (C ) 1997 John Wiley & Sons, Inc.