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Proceedings Paper

Photo-fluids as optical sensors and data storage materials
Author(s): Peter Karageorgiev; Dieter Neher; Burkhard Schulz
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Paper Abstract

An increase in stochastic molecular vibrations of a solid due to heating above the melting point leads to a decrease in its long-range order and a loss of structural symmetry. Therefore conventional liquids are isotropic media. We report on a light-induced isothermal phase transition of polymer materials from an isotropic solid to an anisotropic liquid state in which the degree of mechanical anisotropy can be controlled by light. Whereas during irradiation by circular polarized light the materials behave as an isotropic viscoelastic fluid, they display considerable fluidity only in the direction parallel to the light field vector under linear polarized light. In this case the polymers behave visually as a liquid along one direction and as a solid in others (one-direction liquid-state), demonstrating thus extraordinarily anisotropic mechanical properties. The fluidisation phenomenon is related to photoinduced motion of azobenzene-functionalised molecular units, which can be effectively activated only when their transition dipole moments are oriented close to the direction of the light polarization. We also show that the selective excitation of chromophores orientated parallel to the light polarization not only has great influence on the anisotropy of the mechanical properties of the materials, but also induces an anisotropic expanding force, which can be used for polarization-selective opto-mechanical actuators and sensors.

Paper Details

Date Published: 20 April 2006
PDF: 7 pages
Proc. SPIE 6192, Organic Optoelectronics and Photonics II, 61921G (20 April 2006); doi: 10.1117/12.662484
Show Author Affiliations
Peter Karageorgiev, Ctr. of Advanced European Studies and Research (Germany)
Univ. Potsdam (Germany)
Dieter Neher, Univ. Potsdam (Germany)
Burkhard Schulz, Univ. Potsdam (Germany)

Published in SPIE Proceedings Vol. 6192:
Organic Optoelectronics and Photonics II
Paul L. Heremans; Michele Muccini; Eric A. Meulenkamp, Editor(s)

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