Synthesis and UV absorption properties of 5-sulfosalicylate-intercalated Zn-Al layered double hydroxides

5-sulfosalicylic acid (SSA) anions have been intercalated into layered double hydroxides (LDHs) by an anion-exchange reaction using ZnAl-NO3-LDH5 as a precursor. The samples were characterized by XRD, FT-IR, TG-DTA/MS and UV visible spectroscopy. The results show that the NO3- anions in the precursor have been completely replaced by SSA anions to give ZnAl-SSA-LDHs having a high degree of crystallinity. Detailed studies reveal the existence of a supramolecular structure in ZnAl-SSA-LDHs involving electrostatic attraction between opposite charges, hydrogen bonding and other weak chemical bonding interactions between host layers and SSA anions. The thermal stability of ZnAl-SSA-LDHs is considerably enhanced compared with that of a mixture of ZnAl-NO3-LDHs and SSA. After addition of 2.0wt% ZnAl-SSA-LDHs to polypropylene (PP), the resistance of the polymer to UV degradation is significantly improved. (C) 2007 Elsevier Inc. All rights reserved.