Dresden 2006 – scientific programme
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CPP: Chemische Physik und Polymerphysik
CPP 6: Electronic Structure and Spectroscopy I
CPP 6.12: Talk
Monday, March 27, 2006, 17:30–17:45, ZEU 114
Photo-induced deformations in azobenzene-containing side-chain polymers: molecular dynamics study — •Jaroslav Ilnytskyi1, Marina Saphiannikova2, and Dieter Neher1 — 1Institute for Physics, University of Potsdam, Am Neuen Palais 10, 14469 Potsdam, Germany — 2Leibniz Institute of Polymer Research, Hohe Str. 6, 01069 Dresden, Germany
The photo-induced deformations in azobenzene containing side-chain polymers and elastomers are studied by means of molecular dynamics (MD) simulations on semi-atomistic models. The phase diagrams for both polymers are built and initial configurations in nematic and smectic phases are prepared in a number of ways. By driving the elastomer system through the orientational phase transition, the reversible contraction of the sample have been reproduced. The photo-mechanical responce of both polymers involved the modelling of the photoisomerization of the azobenzenes. That was done in a simplified way, by considering solely the effect of reorientation of the trans isomers perpendicularly to the light polarization. We found the effect strongly dependent on the optical field strength. In weak fields the photo-chemical phase transition takes place and for the case of nematic elastomer the reversible shrinking along the optical field is observed. In the case of side-chain polymer in stronger fields, the rapid initial shrinking of the sample (similar to the case of elastomer) is followed by slow self-organisation of new smectic layers with the chromophores perperdicular to the light polarization (the light induced order).