Nonlinear diffusion and phase separation

Non-Fickian diffusion driven by gradients in chemical potential rather than concentration is important for nonideal mixtures, Conventional formulations of the chemical potential must be supplemented by gradient term whenever phase separation is possible, Equilibrium composition profiles are predicted in both confined and large systems using the Landau-Ginzburg functional, Parameter estimates based on mean-field theories work well for polymers, The dynamics of phase change are described by the modified Cahn-Hilliard equation, Domain growth in quiescent systems occurs by Ostwald ripening and by hydrodynamics induced by concentration gradients. Simulations without adjustable constants are used to predict non-equilibrium morphologies in binary and ternary polymer, Experimentally confirmed morphologies include dual-continuous phases, dual-dispersed phases, core-shell particles and more complex structures, Most impurities are enriched at the phase boundaries. (C) 2001 Published by Elsevier Science Ltd.