Induction of the vector polyphotochromism in side-chain azopolymers

Abstract

Highlights  We found the effect of photoinduced changes in the spectral properties of the material within the entire visible range.  The further investigation of this vector polyphotochromic effect is presented.  Phenomenon is related to the photoelastic interference quenching of probing beams.  We prove the relationship between the chemical composition and material optical properties.

Liquid Crystalline Copolymers Containing Sulfonic and Light-Responsive Groups: From Molecular Design to Conductivity

“…We also note that the π-π* transition band retains some residual absorbance after irradiation at 365 nm, as seen in Figure 7b, which suggests that trans-to-cis isomerisation is hindered in bulk, at least to some extent. This behaviour could not be explained, at least solely, by the greater concentration of azobenzene aggregates in the films, but also by the presence of interactions between the azobenzenes and other functional groups in the copolymers (AMPS and MMA) [52,[63][64][65][66], which are both consistent with our model proposed in Figure 6. Upon irradiation with UV light at 365 nm, the azobenzene groups undergo trans-to-cis isomerisation, and, as a result, the absorption band π → π* shifts to shorter wavelengths by a hypsochromic effect (~320 nm), and simultaneously decreases in intensity.…”

Light-responsive bent-core liquid crystals as candidates for energy conversion and storage

“…[66] Upon UV irradiation (365 nm; 260 mW•cm -2 ), the azobenzenes undergo trans-to-cis photo-induced isomerisation, evidenced by a decrease in the ~365 nm band and a simultaneous (slight) increase of the ~440 nm band, illustrated for IP31 in Fig7(b). When the solutions are kept in the dark after illumination, the UV-vis spectra recover their initial shape (prior to UV illumination) before 24 hours after exposure, due to thermally induced cisto-trans back-relaxation of the azobenzene groups [67], see also Fig. S10.…”

Ionically conducting and photoresponsive liquid crystalline terpolymers: Towards multifunctional polymer electrolytes

“…The presence of the azobenzene-based groups will allow control of their macroscopic properties using light stimuli via changes in the local order. 15,[30][31][32][33][34][35][36]…”