Polarization Dependent Photoinduced Supramolecular Chirality in High-Performance Azo Materials

Abstract

Here, we will show photo-induced supramolecular chirality in thin films of achiral amorphous polymers with azo groups in their side-chain. A matter of particular interest is the effect of various film thicknesses on azimuthal rotation and ellipticity of incident/transmitted polarized light. Furthermore, we investigated the temporal stability of inscribed chirality. By polarimetric measurements, we found out that the azimuthal rotation gets higher with layer thickness. In this scope, we were able to measure a very high azimuthal rotation of Δψ/d=112.5∘/μm. The inscribed chirality was stable for several days. Furthermore, we investigated the time-resolved behavior of incident and transmitted polarization ellipticities for various thicknesses. The time dependency may be explained by a two-step process: (1) fast trans-cis-isomerization resulting in photo-orientation and (2) slow photo-induced mass flow.

Reversible Photo-Induced Reshaping of Imprinted Microstructures Using a Low Molecular Azo Dye

“…Therefore, it is suspected that the stretching quantity behaves similar to the stretching behavior itself, namely with a fast beginning increase and ending in reaching slowly a saturation point. This behavior is very similar to well known photo-induced surface and bulk structuring of azo films [ 56 , 57 , 58 , 59 ].…”

“…For further investigations samples with medium AZOPD concentration (Azo30) were selected in order to set the duration for illuminating the samples. The illumination duration of 2, 10, and 30 min were chosen for the Azo30 sample based on previous report [ 56 ].…”

“…At this step, azo molecules move or flow parallel to the polarization plane. This process is temporally limited and stops after reaching a saturation point [ 27 , 34 , 37 , 39 , 46 , 47 , 56 , 57 ]. As can be seen in Figure 6 , the time dependency of light-induced stretching can be confirmed.…”