Phase-separation dynamics in binary polymer blends

We study a continuum model for phase-separation in binary polymer blends based on the Cahn-Hilliard equation with the Flory-Huggins-De Gennes free-energy functional and a concentration-dependent mobility. The model is solved analytically, by means of the self-consistent large-n limit approach, and numerically for values of the parameters corresponding to the weak and strong segregation limits, for both critical and off-critical blends. For deep quenches me identify a complex structure of intermediate regimes and crossovers and the existence of a time domain characterized by the pinning of the phase-ordering process. The duration of this stop is analytically computed and diverges differently when the chains length is increased or the temperature is lowered. This result allows the interpretation of recent experiments which show pinning in off-critical polymeric mixtures suggesting that the continuum model contains sufficient physical ingredients to explain the experimental evidence.