Efficient surface-relief gratings in hydrogen-bonded polymer-azobenzene complexes

We show that efficient photoinduced surface-relief gratings can be inscribed in polymer-azobenzene complexes which are bonded by phenol-pyridine hydrogen bonding. The grating inscription was studied as a function of chromophore concentration and the molecular weight of the host polymer, both of which can be easily tuned without demanding organic synthesis. Stable gratings with modulation depth as high as 440 nm and with diffraction efficiency exceeding 40% were inscribed in the equimolar complexes. Our results demonstrate that phenol-pyridine hydrogen bonding not only allows one to increase the chromophore content until each polymer unit is occupied but is also sufficiently strong to induce mass migration of the polymer chains in a manner comparable to covalently functionalized polymers.