Calix[4]arene-derivative surfactants form monodisperse micelles with a well defined aggregation number (Nagg), the value of which is selected from among 4, 6, 8, 12, and 20, corresponding to the Platonic solids. This feature is in strong contrast to conventional micelles. Here, we focused on a kinetics; a transition from dodecamer (Nagg = 12) to icosamer (Nagg = 20) induced by a rapid increase of the NaCl concentration (CNaCl) using a stopped-flow device was directly observed with time-resolved small-angle X-ray scattering. Nagg was unchanged during 60 s after CNaCl increased, and then abruptly increased to 20. This phenomenon is similar to the phase transitions in a supersaturated or supercooled state, or highly cooperative phenomena. The phenomena may be related to our hypothesis that only a few Nagg values are thermodynamically allowed, when Nagg is sufficiently small. This is the first observation of such abnormal discontinuous change in micellar aggregation behavior.

Platonic micelles part 2: Thermodynamic and kinetic consideration of the micelles with the discrete aggregation numbers and mono-dispersity

255th National Meeting (2018)

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