Prepared And Property Study Of Pillared LDHs With Organic UV Absorbent

Five organic UV absorbents, p-(dimethylamino) - benzoic acid, 2-Phenylbenzimidazole-5-Sulfonic acid, p-methoxy benzoic acid, 2,3-dimethoxy benzoic acid, 2,4-dimethoxy benzoic acid, in their anionic, has been intercalated into a layered double hydroxide (LDHs) host by coprecipitation method. Five organic-inorganiccomposite materials, Zn₂Al-LDH/PDMABA, Zn₂Al-LDH/UV-T, Zn₂Al-LDH/ PMOBA, Zn₂Al-LDH/2,3-DMOBA and Zn₂Al-LDH/2,4-DMOBA were obtained. Products obtained were characterized by X-ray diffraction (XRD), FT-IR, UV-Vis, TG-DTA. Thermal stability, UV shielding ability, catalytic activity for the air of castor oil and chemical stablility of the composite materials were investigated.The results indicated that synthetic products had well layered brucite-like structure in control of the experimental condition (Zn/Al=2.0, pH≈9.0, Aging Temperature=70℃, Aging Time=24h). Results suggested that the intercalated organic UV ray absorbents still maintained their original structures in the interlayer. The orientation and arrangement of the organic anions within the interlayer of the LDHs had also been investigated. Crystallite size in direction a is 13-20nm and crystallite size in direction c is 13-28nm.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, all Zn₂Al-LDHs/organic UV absorbent molecule nanocomposites showed excellent UV-shielding ability and transparency in the visible light region. In comparison with unsupported organic UV absorbents, the catalytic activity for the air of castor oil of the organic UV ray absorbents-pillared layered double hydroxides substantially decreased, so far as to be lower than the blank reaction without additives. The Zn₂Al-LDHs layer had protection to the interlayer organic anionion.The incorporation of organic UV absorbents in interlayer of Zn₂Al-LDHs avoided the direct contact of the organic molecule and skins. The Zn₂Al-LDHs/organic UV absorbents, which were easy to prepare in laboratory, were sunscreen stability, little catalytic activity and thermal stability. Thus, a new protection sunscreen model had been designed. It is promising to use in cosmetic.