Studies On Assembly And Properties Of Organic UV Ray Absorbents-Pillared Layered Double Hydroxides

In the thesis, several organic ultraviolet (UV) ray absorbents, such as cinnamic acid (CA),p-methylcinnamic acid(PMCA), p-methoxycinnamic acid (PMOCA), 3,4-dimethoxycinnamicacid (DMOCA), p-hydroxycinnamic acid (PHCA) and 4-hydroxy-3-methoxycinnamic acid(HMOCA),in their anionic forms, were intercalated into the interlayer space of Zn2Al layereddouble hydroxides (Zn2Al-LDHs) by co-precipitation reaction. Six organic-inorganiccomposite materials, cinnamic acid series organic UV ray absorbents-pillared layered doublehydroxides, Zn2Al-LDHs were obtained. Materials characterization was carried out usingX-ray diffraction (XRD), FT-IR, UV, TG-DTA and scanning microscopy (SEM). Thermalstability, UV-shielding ability and catalytic activity for the air of castor oil of the compositematerials were investigated.The results indicated that Zn2Al-LDH/organic UV absorbent composites hadwell-organized stacking arrangement by controlling experimental conditions. XRD patternsshowed that the basal spacing of Zn2Al-LDHs were greatly expanded as 1.80 nm(Zn₂Al-LDH/CA), 1.96 nm (Zn₂Al-LDH/PMCA), 2.02 nm (Zn₂Al-LDH/PMOCA), 1.91 nm(Zn₂Al-LDH/-DMOCA), 1.76 nm (Zn₂Al-LDH/PHCA) and 1.75 nm (Zn₂Al-LDH/HMOCA)respectively. FT-IR and UV results suggested that the intercalated organic UV ray absorbentsstill maintained their original structures in the interlayer. The orientation and arrangement ofthe organic anions within the interlayer of the LDHs had also been investigated. The hostmaterials can meet the matching of volume, electricity and construction of the guestmolecules, so organic anions turned the functional groups perpendicularly to LDHs layers.Electrostatic interaction and hydrogen bonds were main factors in affecting the basal spacingof Zn2Al-LDHs.TG-DTA analysis showed that the composite materials had well thermal stability.According to the UV-Vis transmittance spectra of thin films of the samples, allZn₂Al-LDH/organic UV absorbing molecule nanocomposites showed excellent UV-shieldingability and transparency in the visible light region. In comparison with unsupported organicUV absorbents, the catalytic activity for the air of castor oil of the organic UV rayabsorbents-pillared layered double hydroxides substantially decreased, so far as to be lowerthan the blank reaction without additives.