Effective Core and Corona Block Sizes for Approximating Micelle Formation Pressures and Micelle Aggregation/Precipitation Pressures in Polystyrene-Block-Polybutadiene and Polystyrene-Block-Polyisoprene Solutions in near Critical Propane From SAFT

The statistical associating fluid theory version referred to as SAFT1 is demonstrated to represent the bulk and micellar phase transitions of polystyrene-block-polybutadiene and polystyrene-block-polyisoprene copolymer solution in propane when reduced segment approximation (RSA) and secluded segment approximation (SSA) are applied to calculate effective corona (diene) and core (styrene) block sizes. The RSA considers a reduced segment number for the corona-forming block to compensate the supposedly soluble block upon micellization transition, hence RSA can fit SAFT1 to micellization pressure of polystyrene-block-polydiene solution in propane. The SSA considers the micelle core excluded from interaction with the solvent during precipitation of micelle from the solution. The SSA can fit SAFT1 to micellar cloud pressure of polystyrene-block-polydiene solution in propane.