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.