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Dynamics and structure in complex liquids under shear explored by neutron scattering
Max Wolff1, Andreas Magerl, Bernhard Frick
1Lehrstuhl fuer Kristallographie und Strukturphysik, Universitaet Erlangen-Nuernberg, 91054 Erlangen, Germany. v-wolff@ill.fr
Physical Review. E, Statistical, Nonlinear, and Soft Matter Physics
|February 9, 2005
Summary
Shear affects triblock copolymer structures in water. Monomer diffusion becomes anisotropic under shear, slowing in the flow direction due to structural ordering.
Area of Science:
- Polymer Science
- Soft Matter Physics
- Rheology
Background:
- Triblock copolymers in aqueous solutions form polymer micelles.
- High concentrations and increasing temperatures induce micelle crystallization.
- Crystalline polymer micelle phases rearrange under applied shear stress.
Purpose of the Study:
- To correlate the structural arrangements of polymer micelles with microscopic dynamics.
- To investigate the effects of shear on monomer and solvent dynamics.
- To understand how structural ordering influences diffusion anisotropy.
Main Methods:
- Utilizing triblock copolymers in aqueous solutions as a model system.
- Applying shear to induce structural rearrangements and observe dynamic changes.
- Correlating macroscopic structural changes with microscopic monomer and solvent dynamics.
Main Results:
- Monomer dynamics are influenced by the arrangement of polymer micelles.
- Pronounced structural ordering leads to anisotropic monomer diffusion under shear.
- Diffusion along the shear gradient is slower than diffusion in the flow direction.
Conclusions:
- Shear-induced structural ordering in polymer micelles significantly impacts monomer dynamics.
- Anisotropic diffusion of monomers is a key characteristic of sheared polymer solutions.
- Understanding these dynamics is crucial for applications involving flowing soft materials.