We investigate the dynamics of kinetically frozen block copolymer micelles of different softness across a wide range of particle concentrations, from the fluid to the onset of glassy behavior, through a combination of rheology, dynamic light scattering and pulsed field gradient NMR spectroscopy. We additionally perform Brownian dynamics simulations based on an ultrasoft coarse-grained potential, which are found to be in quantitative agreement with experiments, capturing even the very details of dynamic structure factors S(Q, t) on approaching the glass transition. We provide evidence that for these systems the Stokes-Einstein relation holds up to the glass transition; given that it is violated for dense suspensions of hard colloids, our findings suggest that its validity is an intriguing signature of ultrasoft interactions.
@article{arxiv.1508.07241,
title = {Validity of Stokes-Einstein Relation in Soft Colloids up to the Glass Transition},
author = {Sudipta Gupta and Jörg Stellbrink and Emanuela Zaccarelli and Christos N. Likos and Manuel Camargo and Peter Holmqvist and Jürgen Allgaier and Lutz Willner and Dieter Richter},
journal= {arXiv preprint arXiv:1508.07241},
year = {2015}
}