Micelle Forming Properties of Polystyrene/Polyisoprene AB Block Copolymers.

摘要

If block copolymers (e.g., AB block copolymers) are dissolved in a solvent which is a good solvent for one block, and a poor solvent for the other block, aggregates are formed under certain conditions. Commonly, it is assumed that spherical micelles are formed in which the insoluble block forms the micelle core and the soluble block forms the shell. Static and dynamic light scattering, small-angle X-ray scattering, and viscosity measurements were used to characterize solutions of polystyrene-polyisoprene AB block copolymers with constant molecular weight of polyisoprene and various molecular weights of polystyrene in aniline. Aniline is a selective solvent for polystyrene, is isorefractive with polystyrene, and also has the same electron density as polystyrene. This fact enabled us to measure independently both the core and the total size of the micelles formed. From the data, we were able to obtain a picture of the micelle structure. The hard-sphere model and a model proposed by S. Alexander were applied to interpret the data. Reprints. (aw)