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

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 Zn2Al-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 Zn2Al-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 Zn2Al-LDH host, whilst the photostability was enhanced slightly. In their composites with polyethylene, it was also found Zn2Al-AG28-LDH possessed better thermostability and photostability than AG28 as its sodium salt. (C) 2011 Elsevier Ltd. All rights reserved.