High-Pressure Micellar Solutions of Polystyrene-block-polybutadiene and Polystyrene-block-polyisoprene in Propane Exhibit Cloud-Pressure Reduction and Distinct Micellization End Points

Authors

Winoto Winoto, Soft Materials Laboratory, Department of Chemical & Petroleum Engineering, UniVersity of Wyoming, Laramie, Wyoming
Sugata P. Tan, Soft Materials Laboratory, Department of Chemical & Petroleum Engineering, UniVersity of Wyoming, Laramie, Wyoming
Youqing Shen, Soft Materials Laboratory, Department of Chemical & Petroleum Engineering, UniVersity of Wyoming, Laramie, Wyoming
Maciej Radosz, Soft Materials Laboratory, Department of Chemical & Petroleum Engineering, UniVersity of Wyoming, Laramie, Wyoming
Kunlun Hong, Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee
Jimmy W. Mays, Center for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, Tennessee

Date of this Version

2009

Comments

Published in Macromolecules 2009, 42, 3823-3826.

Abstract

Micellar solutions of polystyrene-block-polybutadiene and polystyrene-block-polyisoprene in propane are found to exhibit significantly lower cloud pressures than the corresponding hypothetical nonmicellar solutions. Such a cloud-pressure reduction indicates the extent to which micelle formation enhances the apparent diblock solubility in near-critical and hence compressible propane. Concentration-dependent pressure-temperature points beyond which no micelles can be formed, referred to as the micellization end points, are found to depend on the block type, size, and ratio. The cloud-pressure reduction and the micellization end point measured for styrene-diene diblocks in propane should be characteristic of all amphiphilic diblock copolymer solutions that form micelles in compressible solvents.