Neutron spin-echo investigation of the dynamics of block copolymer micelles

Abstract

The dynamics of E92B18 (E=OCH2CH2: oxyethylene, B=OCH2CH(C2H5): oxybutylene; the subscripts are the number of repeats) block copolymer micelles is investigated by neutron spin-echo (NSE). The dynamics of chains in E92B18 micelles is investigated in the hard gel and soft gel phases of the E92B18 in D2O, as well as in the micellar solution. NSE revealed the presence of two dynamic modes, i.e., “fast” and “slow” modes, which are observed independent of the phase, i.e., micellar liquid, soft gel or hard gel. A “slow” mode that dominates at low scattering angles corresponds to the translational diffusion of micelles, the micellar size Rs being in good agreement with the apparent hydrodynamic radius from dynamic light scattering experiments on a dilute solution. An additional “fast” mode was observed, and ascribed to internal “blob scattering” in the micellar corona.