Novel photoactive hyperbranched poly(aryl ether)s containing azobenzene chromophores for optical storage

Two novel hyperbranched poly (aryl ether)s with azobenzene moieties in both the main chain and side chain of the branched arms were prepared by using B3 + A2 methodology via a nucleophilic aromatic substitution polycondensation. Structures of the hyperbranched poly (aryl ether)s with azobenzene moieties (azo-HPAEs) were characterized by means of IR, UV-visible, 1H NMR spectroscopy, and XRD. It is shown that both the azo-HPAEs exhibit high glass transition temperatures (Tg), excellent thermal stability and homogeneous photochromic behavior. By exposing their spin-coating films to an interference pattern of laser beam, both the azo-HPAEs could be used for rapid (within 30 s) fabrication of surface-relief gratings (SRGs). The obtained SRGs present no shape changes even at temperatures up to 200 deg C. Especially, the azo-HPAE with azobenzene moieties in the side chain shows larger photoinduced birefringence intensity and better reversible optical storage than the one with azobenzene moieties in the main chain upon irradiation with 532 nm Nd:YAG laser. The novel azo-PAEs are photoactive to UV light (355 nm), making them potentially useful for high density information storage.