Supramolecular structural control and characteristics of p-hydroxybenzoate intercalated hydrotalcite

p-Hydroxybenzoate pillared layered double hydroxides with different Zn/Al mole ratios have been prepared by three different methods: rehydration of calcined LDH precursor, coprecipitation and anion exchange. The products have been characterized by several experimental techniques: PXRD, FT-IR, TG-DTA and UV-vis. PXRD patterns show that the interlayer distance of p-hydroxybenzoic acid (PHBA)-Zn/Al-LDH varies with ratio Zn/Al, from 14.8 to 15.3 Å, indicating that altering Zn/Al ratios can change the arrangement of the intercalated PHBA anions. Not only do infrared spectra display the characteristic absorption of both the PHBA anion and the Zn/Al layer, but also provide further evidence of the interaction between these two parts. Thermal analysis confirms that the intercalation can make PHBA stable up to 434 °C, which is 213 °C higher than that for pure PHBA. By UV-vis it is found that such a product can control blocking of UV radiation in a wider range of wavelength.