Photo-induced deformations in azobenzene-containing side-chain polymers: molecular dynamics study

• Published in: Condensed Matter Physics
• Date: 2006
• Main Authors: Ilnytskyi, J., Saphiannikova, M., Neher, D.
• Format: Article
• Language: English
• Published: Інститут фізики конденсованих систем НАН України 2006
• Online Access: https://nasplib.isofts.kiev.ua/handle/123456789/121287
• Journal Title: Digital Library of Periodicals of National Academy of Sciences of Ukraine
• Cite this: Photo-induced deformations in azobenzene-containing side-chain polymers: molecular dynamics study / J. Ilnytskyi, M. Saphiannikova, D. Neher // Condensed Matter Physics. — 2006. — Т. 9, № 1(45). — С. 87–94. — Бібліогр.: 25 назв. — англ.

We perform molecular dynamics simulations of azobenzene containing side-chain liquid crystalline polymer
 subject to an external model field that mimicks the reorientations of the azobenzenes upon irradiation with polarized
 light. The smectic phase of the polymer is studied with the field applied parallel to the nematic director,
 forcing the trans isomers to reorient perpendicularly to the field (the direction of which can be assosiated with
 the light polarization). The coupling between the reorientation of azobenzenes and mechanical deformation
 of the sample is found to depend on the field strength. In a weak field the original smectic order is melted
 gradually with no apparent change in the simulation box shape, whereas in a strong field two regimes are
 observed. During the first one a rapid melting of the liquid crystalline order is accompanied by the contraction
 of the polymer along the field direction (the effect similar to the one observed experimentally in azobenzene
 containing elastomers). During the slower second regime, the smectic layers are rebuilt to accomodate the
 preferential direction of chromophores perperdicular to the field.