Bridging molecular orientation and isomerization state with macro-deformation in photoactive azobenzene-containing materials

• Applicants: Dr. Olga Guskova; Professorin Dr. Svetlana Santer
• Subject Area: Experimental and Theoretical Physics of Polymers
• Term: from 2016 to 2020
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 289465782

Azobenzene-containing polymers belong to a class of functional materials exhibiting a strong coupling between an external radiation field and mechanical response. Although the electromagnetic field acts only on the photosensitive azobenzene moieties, their attachment to a polymer matrix leads to intriguing phenomena involving the whole system, such as the formation of surface reliefs in thin films. The goal of this joint experimental/theoretical research project is to investigate the impact of various possible forces that emerge in azobenzene-containing thin films at different time and length scales, i.e. in the spirit of multiscale approach. First, it will be verified theoretically how strong the conformational coupling between azo-molecules and the polymer backbone itself is. Complementary to this point of view we shall investigate in how far the response of the polymer film to inhomogeneous intensity/polarization illumination arises from thermodynamic forces originating from spatial gradients in a chemical potential. Third, the morphological/elastic response of thin azo-polymer films will be studied in situ while the system is passing the glass transition temperature. Understanding the mechanisms of the responsive behaviour of photo-sensitive thin polymer films will greatly advance our ability to relate microscopic mechanisms to macroscopic response and to engineer tailor-made systems for technological applications.

• DFG Programme: Research Grants