The effect of photoisomerization ratio and configuration on the macroscopic properties of azobenzene liquid crystal elastomer: A molecular dynamics study

The mechanical and thermal properties of azobenzene liquid crystal elastomers (LCEs) are dependent on photoisomerization. In this paper, molecular models of azobenzene LCEs are firstly established. The photoisomerization process for azobenzene LCEs with different photoisomerization ratio and molecular configuration is discussed, and the impact of the molecular configuration on the macroscopic performance of azobenzene LCEs is clarified on the molecular level. Then, based on the azobenzene LCEs with different photoisomerization ratio and molecular configuration, the mechanical and thermo properties of azobenzene LCEs is investigated. The results indicate that except for photoisomerization ratio, molecular configuration also plays an importance role on the determination of macroscopic responses of azobenzene LCEs. Azobenzene LCEs with the same photoisomerization ratio but different molecular configuration display different photoisomerization process, and the molecular configuration has a significant impact on the yield stress and collapse stress, as well as glass transition temperature. The results obtained in the paper provide a guidance for the macroscopic property tuning based on molecular design of azobenzene LCEs.