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–LDHs 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 2.0 wt% ZnAl–SSA–LDHs to polypropylene (PP), the resistance of the polymer to UV degradation is significantly improved.

UV–visible absorbance curves of SSA (a), ZnAl–NO3–LDHs precursor (b) and ZnAl–SSA–LDHs (c).Figure optionsDownload as PowerPoint slide