Thermodynamic Modelling as a Tool in the Design of Microsphere Controlled-Delivery Systems

We use a simplified multiphase flash formulation based on excess Gibbs free energy models such as the GC-Flory equation of state to calculate the loading of an active ingredient in a polymer matrix, produced by solvent evaporation from a liquid emulsion. We give four case studies of relevance to the development of computer-aided techniques for (1) polymer screening; (2) solvent selection; (3) replacement of the external medium phase for micro-emulsion formation, and (4) incorporating the influence of polymer molecular weights. We also present extensions of the GC-Flory parameter table to include missing group parameters for three amine groups. The parameters are determined by fitting the model to represent experimental phase equilibrium data. Twenty-four new parameters are presented describing three single groups. Twenty-seven new parameters are given for interactions with 14 other groups. Example results of correlation and predictions of real data are provided.