Decompression-Induced Encapsulation of Core-philic Solutes by Block Copolymer Micelles in Compressible Solutions: Polystyrene and Polystyrene-block-polybutadiene in Near-Critical Propane

作者：Winoto Winoto; Radosz Maciej^*

来源：Macromolecules, 2011, 44(13): 5392-5400.

DOI：10.1021/ma2006188

Pressure-tuned propane capacity and selectivity for polystyrene-block-polybutadiene allows for random molecular solutions at high pressures, micellar solutions at moderate pressures, and bulk phase separation at low pressures. While corona-philic homopolymer solutes primarily stay in solution when the micelles are formed, core-philic homopolymer solutes, such as polystyrene, are found to concentrate in and hence become encapsulated by the micelle core. If the concentration of such a block-sized polystyrene solute is in the right range, say up to 15 wt % on a solvent-free basis, it can produce an encapsulation peak on either the transmitted-light intensity trace or the scattered-light intensity trace, or both. Such encapsulation peaks can help detect the onset of micellization and encapsulation, especially when guided by a macromolecular model, such as statistical associating fluid theory (SAFT1), used to estimate the onset of bulk phase transitions in this work. A core-philic solute, free polystyrene in this case, does not alter the crucial micellization pressure or even the micellar cloud pressure, at which the micelles coalesce and precipitate from solution in bulk.

• 出版日期2011-7-12