Optimization of UV Absorptivity of Layered Double Hydroxide by Intercalating Organic UV-Absorbent Molecules (original) (raw)
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Science of Advanced Materials, 2014
Zn/Al-layered double hydroxide (LDH) was used as a host to intercalate various organic ultraviolet (UV) radiation absorbers. The intercalation compounds were prepared via the co-precipitation method. Powder X-ray diffraction (PXRD) confirmed the successful intercalation of anions into the interlayer regions of the LDH nanocomposites. As a result of intercalation, the resulting nanocomposites loaded with UV-ray absorbers, cinnamic acid (CA), benzophenone 4 (B4) and Eusolex ® 232 (EUS)-exhibited basal spacings of 17.9 Å, 21.3 Å and 21.0 Å, respectively. Photochemical analysis revealed an increase in the UV-ray absorption capability of UV absorber/LDH nanocomposites compared to pure UV-ray absorbers. The retention ability of the organic moieties in the LDH host was tested in a skin pH simulation and was found to demonstrate low release over an extended period of time. Cytotoxicity findings indicated that none of the nanocomposites exhibit significant cytotoxicity towards human dermal fibroblast (HDF) cells up to the test concentration of 25 g/mL.
Journal of Colloid and Interface Science, 2013
Layered double hydroxides intercalated with dodecylsulfate or dodecylbenzenesulfonate were synthesized by co-precipitation under alkaline conditions. After characterization by PXRD, FTIR, and TGA/ DTA, the Zn x Al/SUR compounds were reacted with neutral benzophenone, using different procedures. The products obtained from benzophenone adsolubilization were investigated by PXRD, FTIR, and DRUV-Vis spectroscopy before and after exposure to UV radiation. In general, the content of adsolubilized benzophenone was small and depended on the synthetic procedure. The best results were achieved under microwave irradiation, which furnished 9.09 wt% adsolubilized benzophenone. The products presented good adsorption in the full UV region, from UVC to UVA, and good stability to UV radiation. They did not cause skin irritation in tests conducted on rabbits, which makes them good candidates for the development of a new generation of sunscreens.
Zn-Al LAYERED DOUBLE HYDROXIDE AS HOST MATERIAL FOR SUNSCREEN COMPOUND OF p-AMINOBENZOIC ACID
Zn-Al layered double hydroxide can be used as host material for UV active compound p-aminobenzoic acid (PABA), which is having capability to block UV light of sunlight. The formation of Zn-Al-PABA was best developed in which the nucleation process was done at room temperature and followed by hydrothermal treatment at 100 oC. To make a better product, the molar ratio of Zn to Al to PABA was adjusted to 3:1:1. From the elemental analysis and the content of PABA, it was observed that the product has structural formula of Zn0,745Al0.254(OH)1.650(PABA)0.349. 0.684H2O. The particle size of the powder as estimated using SEM was in the range 100-200 nm. FTIR and XRD proved that the p-amino benzoate ion occupied the interlayer space. This material is expected to have high sun protection factor (SPF).
Molecules
In this study, we propose a promising photoprotective additive that combines the advantages of both organic UV absorbers and inorganic particles without compromising the properties of the paint material. This additive involves the intercalation of a well-known organic UV absorber, 2-phenylbenzimidazole-5-sulfonic acid (PBISA), into zinc-aluminum layered double hydroxide (ZnAl-LDH). Three ZnAl-LDH intercalates with PBISA were prepared using various methods based on either anion exchange or direct synthesis. The intercalates were characterized using powder X-ray diffraction, thermogravimetry, elemental analysis, and IR and UV-Vis spectroscopies. The composition and basal spacings of all three intercalates are very similar. An effective UV protection film was prepared when the ZnAl–PBISA–1 intercalate was incorporated into polyurethane-acrylate lacquer. The resultant UV protective film exhibited stability and uniform distribution of the intercalated fillers. Some minimal particle sedim...
Journal of the Brazilian Chemical Society, 2015
Two anionic surfactants, dodecylsulfate (DDS) and dodecylbenzenesulfonate (DBS), were intercalated into layered zinc hydroxide salts (LHS) using the direct alkaline co-precipitation method, and characterized by powder X-ray diffraction (PXRD), Fourier-transform infrared (FTIR) and thermogravimetric analysis/differential thermal analysis (TGA/DTA). Different UV-absorbing organic molecules, like salicylates, cinnamates and benzophenones, were adsolubilized in the LHS interlayer following two different procedures (conventional microwave treatment and microwave with hydrothermal treatment). The adsolubilized products were investigated by PXRD, FTIR, diffuse reflectance UV-Vis (DRUV-Vis) and luminescence spectroscopies before and after exposure to UV radiation. Most of the products showed a good absorption in the UV region, from UVC to UVA, and good stability under UV radiation. The photodegradation tests showed that DDS-intercalated compounds were more stable than those intercalated with DBS. Adsolubilization in LHS can be an interesting alternative to immobilize neutral molecules with UV absorption capability, to prepare materials to be used in sunscreen formulations.
Journal of Polymer Research, 2019
In this research work, ternary (Mg + Zn:Al; M 2+ :M 3+ = 2:1) layered double hydroxides (LDH) intercalated with nitrate and paminobenzoate anions were synthesized through the coprecipitation method at constant alkaline pH. These materials were characterized by several instrumental techniques and used as functional fillers in low-density polyethylene (LDPE), obtaining homogeneous nanocomposites by means of injection molding. In the samples prepared with percentages of 0.5, 2, 4, 6 and 10% by weight in relation to LDPE, maintenance or slight improvement of the mechanical properties was observed for all samples. In the LDPE nanocomposites the UV absorption showed to be higher than neat polyethylene. Weathering experiments performed with the neat LDPE and LDPE nanocomposites containing 5% of maleic anhydride and 5% of LDH intercalated with paminobenzoate demonstrated a decrease of oxidation product generated due to ultraviolet radiation absorption because the organic intercalated specie, indicating that the ternary LDH is a potential filler to protect polymers from UV radiation degradation.
Recent advances in layered double hydroxides applied to photoprotection
einstein (São Paulo), 2019
Layered double hydroxides have received more attention from researchers due to their range of applications, ease of synthesis and low cost of production. With broader knowledge about solar radiation effects on the body, the use of sunscreens has become even more important. The ability of some nanostructures, such as layered double hydroxides, to act as matrices has made it possible to obtain improvements in photoprotective formulations, with solutions to problems caused by radiation and sunscreens. This review article brings together the most recent advances of these clays, the layered double hydroxides, applied to photoprotection.
Journal of the Brazilian Chemical Society, 2020
Zn 2 Al-Cl and Zn 2 Al-NO 3 layered double hydroxides (LDHs) were synthesized through the fixed pH co-precipitation method and used as precursor materials for the intercalation of p-aminobenzoate through anion exchange reactions. Since chloride in Zn 2 Al-Cl was only partially exchanged with p-aminobenzoate, the phases Zn 2 Al-NO 3 and Zn 2 Al-NAB (nitrate exchanged with p-aminobenzoate) were used in different percentages as functional fillers to produce nanocomposites of low-density polyethylene doped with maleic anhydride (LDPE). Analysis of thermal properties showed that the melting and recrystallization temperatures were slightly increased in the nanocomposite containing 5 wt.% Zn 2 Al-NAB. Weathering tests performed with neat LDPE and the nanocomposite films showed that the addition of the LDHs improved ultraviolet (UV) absorption and reduced the LDPE degradation by 25 and 76% when using Zn 2 Al-NO 3 and Zn 2 Al-NAB , respectively, as fillers, showing a promising UV-shielding effect. Preliminary results also showed a potential application of Zn 2 Al-NAB as antioxidant in natural insulating oils (natural ester FR3 and castor oil), opening new opportunity of applications.
Applied Clay Science, 2019
This paper outlines the encapsulation of benzoate and its two derivatives i.e. para-hydroxybenzoic acid (p-BZOH) and 2-chloro-5-nitrobenzoic acid (BZCN) having antibacterial activity in between the interlayer distance of ZneAl layered double hydroxides to form an antibacterial composite material. The three reagents were successfully intercalated in between ZneAl LDH via anion-exchange mechanism. The intercalation was successfully evaluated by the increase in the basal spacing from X-ray diffraction, FTIR and thermogravimetry (TG-DTA) analysis. By variation of incoming reagents, the nature of interlayer arrangement, the tendency of binding, kinetics of release of the reagent from the inorganic lamella and bactericidal effect differ. The novel nanocomposites demonstrated a distinctly enhanced bactericidal effect towards both gram positive (Staphylococcus aureus, MTCC 96) and gram negative (Escherichia coli, MTCC 739) bacterial strains having diverse rate of killing. Also the diffusion of the active molecules out of the nano-composites was found to be very slow and in a sustained manner in case of BZCN as compared to other two. Therefore these newly designed organic-inorganic fusions may offer a promising antimicrobial elucidation to the society.
In vitro photostability and photoprotection studies of a novel ‘multi-active' UV-absorber
Free Radical Biology and Medicine, 2008
This paper reports on the synthesis and properties of a new UV-absorber (OC-NO) based on the most popular UV filter worldwide, ethylhexyl methoxycinnamate (OMC) in which the methoxy group has been replaced with a pyrrolidine nitroxide bearing antioxidant activity. This sunscreen active has therefore both UVabsorbing and antioxidant properties which could ideally address both the UV-B and UV-A skin photodamage. For broad-spectrum coverage, the combinations of OC-NO with two commonly used UV-A absorbers (BMDBM and DHHB) were also studied. The results obtained reveal that OC-NO: (a) is as photostable as OMC after UV-A exposure; (b) acts as free radical scavenger as demonstrated by EPR and chemical studies; (c) reduces UV-A and UV-A+BMDBM induced lipid peroxidation in liposomes and cells, measured as reduced TBARS levels and increased C11-BODIPY red fluorescence, respectively; (d) has comparable antioxidant activity to that of vitamin E and BHT commonly used in skin care formulations; (e) is non-cytotoxic to human skin fibroblasts as assessed with the MTT assay when exposed to increasing doses of UV-A; and (f) OC-NO+ DHHB is a promising, photostable broad spectrum UV-filter combination that concomitantly reduces UVinduced free radical damage. These results suggest that nitroxide/antioxidant-based UV-absorbers may pave the way for the utilization of 'multi-active' ingredients in sunscreens thereby reducing the number of ingredients in these formulations.