Photoinduced surface-relief gratings in films of supramolecular polymer-bisazobenzene complexes

We demonstrate that hydrogen-bonded polymer-azobenzene complexes, containing nonpolar bisazobenzene chromophores, yield efficient photoinduced surface-relief gratings over a wide chromophore concentration range. The efficient grating formation is thought to be enabled by the lack of spacer between the chromophores and the polymer backbone, which prevents the formation of liquid-crystalline phases even at high chromophore concentrations. The surface-modulation depth can be tuned by varying the chromophore content, and the deepest gratings (625 nm) are obtained, when every second polymer repeat unit is occupied by a chromophore. The gratings are thermally erasable by heating the samples above their glass-transition temperature, and no irreversible photodegradation of the chromophores is observed.