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Dynamics and Transport of Molecules in Polymer and Colloidal-Rod Networks

Published online by Cambridge University Press:  01 February 2011

Kyongok Kang
Kyongok Kang*
Affiliation:
[email protected], Forschungszentrum Juelich, IFF-Weiche Materie, Leo-Brandt Str.4, Juelich, D-52425, Germany, +49-2461-61-2149, +49-2461-61-2280
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Abstract

Re-orientational dynamics of liquid crystal molecules in a polymer network subjected to an electric field is studied by means of light diffraction [1]. When the optical pitch of the electric-field induced cholesteric phase is small compared to the optical wavelength of light, dynamic light scattering (DLS) can be performed to extract the relaxation dynamics of the chiral nematic molecules in the presence of the polymer network. Intriguingly, the reactive mesogenic type of polymer network exhibits a confinement effect, which can be probed within the limited range of scattering angles that comply with the structural correlation length in the system [2].

Diffusive mass transport of molecules through a rod network can be studied via fluorescence correlation spectroscopy (FCS) and DLS. Long time self-diffusion of tracer spheres (silica and proteins) in isotropic and nematic colloidal-rod networks (fd-viruses) is systematically studied for various tracer-sphere sizes as compared to the mesh size of the network [3]. In addition, by varying the salt concentration, the relative contribution of electrostatic interactions can be varied. A theory is developed where the diffusion coefficient is expressed in terms of the hydrodynamic screening length of the highly entangled rod-network. The hydrodynamic screening length of rod networks is extracted from diffusion data as a function of the rod concentration both for isotropic and nematic networks [4-5].

Keywords

diffusionbiologicalpolymer
Type
Research Article
Information
MRS Online Proceedings Library (OPL) , Volume 1060: Symposium LL – Bioinspired Polymer Gels and Networks , 2007 , 1060-LL04-05
Copyright
Copyright © Materials Research Society 2008

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References

REFERENCES

1. Kang, K., and Sprunt, S., Phys. Rev. E., 72, 031702 (2005).Google Scholar
2. Kang, K., Chien, L. C., and Sprunt, S., Liq. Cryst. Vol. 29, No. 1, 9–18 (2002).Google Scholar
3. Kang, K., Gapinski, J., Lettinga, M. P, Buitenhuis, J., Meier, G., Ratajczyk, M., Dhont, J. K. G., and Patkowski, A., J. Chem. Phys., 122, 044905 (2005).Google Scholar
4. Kang, K., Wilk, A., Buitenhuis, J., Patkowski, A., and Dhont, J. K. G., J. Chem. Phys., 124, 044907 (2006).Google Scholar
5. Kang, K., Wilk, A., Patkowski, A., and Dhont, J. K. G., J. Chem. Phys., 126, 214501 (2007).Google Scholar
6. Kang, K., and Sprunt, S., Mol. Cryst. Liq. Cryst., Vol. 466, 23–38 (2007).Google Scholar