Collaborators:

Vladimir Toshchevikov, Markus Koch, Bharti Yadav, Vladyslav Savchenko, Nina Tverdokhleb and Olga Guskova

Introduction

Azobenzene polymers have been extensively explored in the last decade as photo-deformable smart materials. They have a number of technical applications as data storage media, aligning layers in display and semiconductor technology, light-controllable artificial muscles, etc. We develop a theory of light-induced deformation of azobenzene polymers both for glassy polymers and for crosslinked azobenzene elastomers. The reorientation of azo-chromophores perpendicular to the polarization of light is found to be a self-sufficient explanation for the photo-mechanics of azo-polymers. The theory demonstrates that the light-induced stress caused by azo-reorientation is enough to deform glassy polymers irreversibly and the sign of deformation (expansion/contraction) depends on the chemical structure of the molecules. The results of the theory are in agreement with molecular dynamic simulations performed by us to study light-induced deformation of azobenzene polymers with different chemical architecture. Presently we study the effects of orientation interactions between chromophores on the light-induced deformation and the kinetics of this deformation.

Cooperation:

• Prof. Svetlana Santer (Potsdam University)
• Prof. Jaroslav Ilnytskyi
• Prof. Seungwoo Lee

Highlights:

1. S. Loebner, B. Yadav, N. Lomadze, N. Tverdokhleb, H. Donner, M. Saphiannikova, S. Santer
   Local direction of opto-mechanical stress in azobenzene containing polymers during surface relief grating formation
   Macromolecular Materials and Engineering, accepted
2. M. Koch, M. Saphiannikova, O. Guskova
   Cyclic photoisomerization of azobenzene in atomistic simulations: Modeling the effect of light on columnar aggregates of azo stars
   Molecules 26 (2021) 7674
3. B. Yadav, J. Domurath, K. Kim, S. Lee, M. Saphiannikova
   Orientation approach to directional photodeformations in glassy side-chain azopolymers
   J. Phys. Chem. B 123 (2019) 3337–3347
4. M. Montagna, O. Guskova
   Photosensitive cationic azobenzene surfactants: Thermodynamics of hydration and the complex formation with poly(methacyrylic acid)
   Langmuir 35 (2018) 311–321
5. V. Toshchevikov, T. Petrova, M. Saphiannikova
   Kinetics of ordering and deformation in photosensitive azobenzene lc networks
   Polymers 10 (2018) 531
6. V. Toshchevikov, J. Ilnytskyi, M. Saphiannikova
   Photoisomerization kinetics and mechanical stress in azobenzene-containing materials
   Journal of Physical Chemistry Letters 8 (2017) 1094-1098