HYDROGELS AT CRITICAL CONDITIONS .1. THERMODYNAMICS AND SWELLING BEHAVIOR

The expansion or collapse of hydrophilic networks exhibiting an upper critical miscibility temperature is described near their critical conditions in terms of thermodynamic theories of phase separation. The volume swelling ratio is expressed in terms of the normalized temperature change away from the critical temperature, and the molecular weight between successive junctions (cross links) of the network. The overall swelling or syneresis behavior can thus be predicted for various hydrogels at different temperatures. © 1990.