Improved thermal and photostability of an anthraquinone dye by intercalation in a zinc–aluminum layered double hydroxides host

Abstract

Intercalation of the dianion of the anthraquinone dye Acid Green 28 (1,4-bis[(4-butylbenzene-2-sulphonate)amino]-5,8-dihydroxyanthraquinone) (AG28 2−) into a Zn 2Al–layered double hydroxides (LDH) has been carried out by an anion-exchange method in an effort to improve its thermostability and photostability. The interlayer distance of the LDH was 1.918 nm after reaction with AG28 2− anions, confirming their intercalation into the interlayer galleries of the LDH host. Infrared spectroscopy and thermogravimetric analysis revealed the presence of host–guest interactions between LDH layers and AG28 2− anions. The thermostability of AG28 as its sodium salt and Zn 2Al–AG28–LDH were compared by thermogravimetric–differential thermal analysis and UV–visible spectroscopy. It was found that the thermostability of AG28 was markedly improved by intercalation into the Zn 2Al–LDH host, whilst the photostability was enhanced slightly. In their composites with polyethylene, it was also found Zn 2Al–AG28–LDH possessed better thermostability and photostability than AG28 as its sodium salt.