Azobenzene–N-salicylideneaniline based aromatic polymers as efficient light-responsive materials

We propose a strategy for the synthesis of light-responsive polymers with azobenzene and N-salicylideneaniline units as the backbone. The polymers were prepared by condensation polymerization of tetrafluorobenzene- or octafluorobiphenylene-based bis-hydroxybenzaldehydes with aromatic meta-linked octafluorobiphenylene-based diamines. A model azo-azomethine-based dye was synthesized to confirm the formation of imine bonds between the bis-hydroxybenzaldehyde used in this study and aromatic amine (2-aminophenol). The synthesized polymers were successfully solution-cast into flexible solid films with a tensile strength of approximately 20 MPa, high values of Tg (>235 оС) and good thermal stability (up to 365 °C). Photoisomerization and light-induced birefringence changes in the polymer films were achieved upon photoirradiation with typical UV light at 365 nm, and by using both polarized and non-polarized blue and green light. Finally, we demonstrated the ability of the developed polymer films to record optical information in the form of diffraction gratings.