Expulsion of unimers from polystyrene-block-poly(acrylic acid) micelles-Wangqing Zhang

The pH response of the micelles of polystyrene-block-poly(acrylic acid) (PS200-b-PAA78) in water is studied using a combination of techniques: static light scattering (SLS), dynamic light scattering (DLS), and transmission electron microscopy (TEM). The structure of the micelles in dilute aqueous solution is dependent on pH. At pH values <2.5, the micelles precipitate. At pH values from 2.5 to 3.5, the micelles associate to form micellar clusters. At pH values ranging from 3.5 to 8.0, the micelles are dynamically frozen. At pH > 8.1, some PS200-b-PAA78 unimers gradually escape from the micelles and subsequently re-associate to form smaller micelles.

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