Mathematical Modeling of Structure Evolution in Phase Separating Polymer Systems

2 Mathematical Modeling of Structure Evolution in Phase Separating Polymer Systems 

For a binary polymer/sol vent system, the evolution of polymer composition (wt fraction) via spinodal decomposition has been derived by Caneba and Soong (1985b), resulting in the following equation  

During the early-stage spinodal decomposition, it suffices that the mobility coefficient, M c), and the thermodynamic factor,/ (c), to be constant at c=Co. In this case, Eqs. (1.4.1) and (1.4.2) reduce to 

For a model system wherein the resulting composition profile can properly approach both binodal compositions, quadratic D c) and Af(c) are required, such as 

Simulation results in binary amorphous polymer/solvent systems have been obtained for a poly(methyl methacrylate) (PMMA)/sulfolane system (Caneba and Soong, 1985b), which has a UCST of 51°C. For a polystyrene (PS)/cyclohexanol system with a UCST of 82°C, simulation results are presented by Caneba and Saxena (1996). Table 1.4.1 shows parameter values used in these systems. 

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