Performance analysis of photo-liquefiable azobenzene derivatives for improving the responsive ability of their functional devices

Abstract

Room temperature photo-liquefiable azobenzene derivatives have a high application value in solar energy storage, optical actuators, reversible adhesives and other fields. It is necessary to improve their phase transformation performance continuously for improving the responsiveness of their functional devices. The rate of phase transition response between solid and liquid states is one of the most important features that can be enhanced. However, there is still no relatively systematic research scheme that can quantitatively monitor the dynamic process of its phase transition. Here, a group of small molecular azobenzene derivatives with different substituents were taken as the research objects. Two video analysis methods, the black area pixel statistical method (BAPS) and the reference frame difference analysis method (RFDA), were used together to describe the phase transition process via a mathematical language. Subsequently, the steady state absorption spectrum, the transient absorption spectrum and simulation calculations were combined to find the principles of different phase change performance, indicating that both the photochemical reaction rate and the intermolecular interaction can directly affect the phase transition rate of photo-liquefiable azobenzene derivatives. Finally, a flexible optical actuator with a composite structure was taken as an example. It demonstrated the importance of selecting the compound with the best photoinduced phase transformation performance as the material component for improving the responsive ability of the device. This study fully reveals the correlation and consistency between molecular level photochemical reactions, macroscopic photoinduced phase transitions and functional devices of azobenzene derivatives.