Synthesis, characterization and photoresponsive behaviour of a series of azobenzene-containing poly(ether sulfone)s with high glass transition temperatures

To improve the stability of photoinduced birefringence, a series of azobenzene-functionalized poly(ether sulfone)s (azo-PES) with high glass transition temperature (Tg) were successfully synthesized via Ullmann coupling between PES with bromine side groups and azo compound 4-((4-methoxyphenyl)diazenyl)phenol. Their chemical structures and properties were characterized by means of ultraviolet–visible and proton nuclear magnetic resonance spectroscopies. The results of differential scanning calorimetry and thermogravimetric analysis suggested that the polymers had high Tgs and good thermal stability. Upon irradiation with a 532 nm neodymium-doped yttrium aluminium garnet (Nd:YAG) laser beam, these azo polymers presented large photoinduced birefringence with a remnant value up to 94%, indicating good stability of the photoinduced orientation. Furthermore, multiple writing/erasing experiments indicate that the azo polymers have potential applications in reversible optical storage.