TEMPERATURE HYSTERESIS AND MORPHOLOGY OF VOLUME PHASE-TRANSITION OF GELS

Temperature hysteresis is theoretically studied for the volume phase t ransition of chemically cross-linked gels. The condition of the appear ance of a ''surface skin layer'' of new phase is formulated and calcul ated. The result predicts that the surface skin layer is destabilized near the critical point of the transition due to volume fluctuations. We discuss the relevance of this result to inaccessibility to the Isin g critical point [L. Golubovic and T. C. Lubensky, Phys. Rev. Lett. 63 , 1082 (1989)].