Pattern Formation in Variety of Gels

Spontaneous pattern formations are fundamental characteristics of systems under thermodynamically open conditions. Polymer gel of a cross-linked polymer network immersed in liquid shows rich spatiotemporal pattern formations since it is a typical open system exchanging its matter and energy with the surroundings [158]. Gel reversibly swells and shrinks when the external condition, such as temperature or solvent composition, varies[164, 200]. 

When ionized acrylamide polymer gel undergoes extensive swelling, an extremely fine pattern appears on the surface, and evolves with time[201]. On the other hand, when cylindrical gels of acrylamide shrink, they exhibit bubble pattern and bamboo-like pattern[202]. Under certain conditions, alternate swollen and shrunken portions appear (bubble pattern). In other cases, cross-sectional planes made of the collapsed gel membrane, whose thickness comparable to the wavelength of light, appear in the cylinder (bamboo-like pattern). Gel has also played an important role in the study of the Belousov-Zhabotinsky (BZ) reaction [168, 203], which induces spatiotemporal patterns like the Turing pattern [204, 205] and spiral wave [206]. In the reaction, gel works as supporting 

The polymer gel we utilized has been known for bending mechanism, but has not been investigated from the viewpoint of pattern formation. The patterns generated in this chapter were discovered for the first time. There should be 

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