A novel photoactive hyperbranched poly(aryl ether ketone) with azobenzene end groups for optical storage applications

A novel hyperbranched poly(aryl ether ketone) terminated by azobenzene chromophores (azo-HPAEK) was prepared using 1,3,5-tris[4-(4-fluorobenzoyl)phenoxy] benzene (B3) as a core molecule, 4,4′-(hexafluoroisopropylidene) diphenol as an A2 monomer and 4-(4-hydroxyphenylazo) benzonitrile as an end-capping reagent. It is shown that azo-HPAEK exhibits a high glass transition temperature (Tg), excellent thermal stability and homogeneous photochromic behavior. By exposing the spin-coated film to a laser beam interference pattern, azo-HPAEK can be used for rapid (within 30 s) fabrication of surface relief gratings (SRGs), and the azo-HPAEK gratings cannot be totally erased by heating, even at 300 °C. In particular, azo-HPAEK shows a large photoinduced birefringence intensity and good reversible optical storage upon irradiation with 532 nm Nd:YAG laser.