Aggregating block copolymers as model systems to study polymer brush dynamics |
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Authors: | M Monkenbusch D Schneiders D Richter B Farago L Fetters J Huang |
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Institution: | 1. Institut für Festk?rperforschung, Forschungszentrum Jülich, KFA D-52425, Jülich, Germany 2. Institute Laue Langevin, BP156X, 38041, Grenoble, France 3. Exxon Research and Engineering Company, 08801, Annandale, NJ, USA
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Abstract: | Summary A-B block copolymers in a selective solvent—good for the B-species and bad for the A-species—form micellar aggregates with
a compact A-core with a corona (brush) of B ?hairs? reaching into the solvent. Whereas polystyrene(PS)-polyisoprene(PI) in
decane forms spherical micelles with a PS core of about 10 nm radius, polyethylene(PE)-polyethylenepropylene(PEP) forms micellar
platelets, the shape of which is goverend by the habitus of PE crystallites forming the core. These planar aggregates have
large (several hundred nanometers) lateral extension and a core thickness in the range of 10 nm. Both systems are model systems
for polymer brushes, either on a spherical surface or planar. Neutron spin-echo experiments allow for the investigation of
the dynamics of the brushes which reflects their viscoelastic properties. Results of neutron small-angle and spin-echo investigations
are reported. The brush dynamics is explained using a model based on an idea of de Gennes describing the brush properties
in terms of scaling relations for osmotic pressure and viscosity of a semi-dilute solution with inhomogeneous density.
Paper presented at the I International Conference on Scaling Concepts and Complex Fluids, Copanello, Italy, July 4–8, 1994. |
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Keywords: | Neutron scattering techniques (including small-angle scattering) |
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