Volume Phase Transition of Gels under Uniaxial Tension

We present the first experimental evidence of the effect of uniaxial tension on a volume phase transition (or gel-gel transition) of polymer gels. With an increase in the magnitude of tension, the first-order transition temperature T 0 of poly-N-isopropylacrylamide/water gel increases and the size discontinuity at the transition becomes larger. These results are consistent with a phenomenological theory of volume phase transition of gels under anisotropic stress. The magnitude of the shift of T 0 with tension can be correctly predicted using empirical parameters determined in previous studies.