COUPLING BETWEEN DIFFUSION AND DEFORMATION OF GELS IN BINARY SOLVENTS- A MODEL STUDY

We study theoretically the dynamics of chemically crosslinked gels in binary solvents on the basis of the Flory-type model and nonequilibriu m thermodynamics. We find with the aid of numerical integration of the evolution equation that an instability occurs in the gel upon changin g the composition of the surrounding solution. This instability is cau sed by a marked difference of timescales between quick mutual diffusio n of solvent molecules and slow deformation of the gel network. Profil es of solvent composition and network deformation are also described i n some details.