Photochromic supramolecular azopolyimides based on hydrogen bonds

• We obtained photooptically active supramolecular azopolymers based on the hydrogen bonds.
• As matrixes poly(esterimide)s and poly(etherimide)s with phenolic hydroxyl or carboxylic groups were applied.
• We investigated thermo-optic and photoinduced properties of prepared azopolymers.
• The photoresponsive behavior of the azo-assemblies was tested in holographic recording experiment.

The approach of deriving new photoresponsive active supramolecular azopolymers based on the hydrogen bonds is described. Polymers with imide rings, i.e., poly(esterimide)s and poly(etherimide)s, with phenolic hydroxyl or carboxylic groups were applied as matrixes for the polymer–dye supramolecular systems. Supramolecular films were built on the basis of the hydrogen bonds between the functional groups of the polymers and various azochromophores, that is, 4-phenylazophenol, 4-[4-(6-hydroxyhexyloxy)phenylazo]benzene, 4-[4-(6-hexadecaneoxy)phenylazo]pyridine and 4-(4-hydroxyphenylazo)pyridine. The hydrogen bonding interaction in azo-systems were studied by Fourier transform infrared spectroscopy and for selected assembles by 1H NMR technique. The obtained polyimide azo-assembles were characterized by X-ray diffraction and DSC measurements. H-bonds allow attaching a chromophore to each repeating unit of the polymer, thereby suppressing the macroscopic phase separation except for the systems based on 4-[4-(6-hydroxyhexyloxy)phenylazo]benzene. H-bonds systems were amorphous and revealed glass transition temperatures lower than for the polyimide matrixes (170–260 °C). The photoresponsive behavior of the azo-assemblies was tasted in holographic recording experiment.