|218. Loos, K.; Böker, A.; Zettl, H.; Zhang, M.; Müller, A.H.E.; Krausch, G.: Micellar Aggregates of Amylose-block-Polystyrene Rod-Coil Block Copolymers in Water and THF, Macromolecules 38, 873-879 (2005) -- DOI: 10.1021/ma0345549|
Amylose-block-polystyrenes with various block copolymer compositions were investigated in water and in THF solution. Fluorescence correlation spectroscopy, dynamic light scattering (DLS), and asymmetric flow field-flow fractionation with multi-angle light scattering detection indicate the presence of unimers, oligomers, and large micellar species in THF. Up to four different species were detectable by DLS with hydrodynamic radii ranging from a few nanometers to > 10 µm, indicating that the system is not in a thermodynamic equilibrium state. Collapsed aggregates were monitored on a silicon surface by scanning force microscopy and transmission electron microscopy. In water, crew-cut micelles were obtained from the same block copolymers by a single solvent approach, using elevated temperature and pressure. These crew-cut aggregates are much more uniform than the respective star aggregates in THF and their radii scale with Rh∝ Ncore1/4; Rh∝ Ncorona1/6 in solution and with R ∝ Ncore1/4; R∝ Ncorona1/2 on a silicon surface.
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