Collective dynamics of tethered chains: Breathing modes.

Polystyrene (PS)-polyisoprene (PI) diblock copolymers dissolved in n-decane aggregate into spherical micelles with a PS core and a corona of tethered PI chains. The PI corona may be considered as a brush on the surface of a sphere or as the outer part of a many-armed polymer star. The thermal density fluctuations of the PI corona have been observed by neutron spin-echo spectroscopy. The peculiar multi-decay time relaxation behavior can be described remarkably well by a model based on an idea of de Gennes for treating the corona as a semidilute polymer solution with varying concentration profile.