Mechanical phase diagram of shrinking cylindrical gels.

When polymer gels are subjected to an external stimulus such as temperature or solvent change, they undergo a phase transition often driving pattern formation. In this paper, we use an elastic model to investigate the linear stability of shrinking cylindrical NIPA gels. This model exhibits bubble and bamboo patterns. The wavelengths of these patterns and their phase diagram are in agreement with the experiment of Matsuo and Tanaka [Nature (London) 358, 482 (1992)].