Functionalization of ZnAl-Layered Double Hydroxide with Ensulizole and Its Application as a UV-Protective Agent in a Transparent Polymer Coating

Abstract

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 sedimentation and aggregation were observed on the cured film’s underside, but did not compromise the films’ UV protective properties. The prepared lacquers with intercalated fillers offer a viable solution for the surface modification of plastic products.

Study on the Thermal Stabilizing Process of Layered Double Hydroxides in PVC Resin

“…Additionally, LDHs contain interlayer water molecules that can be removed without damaging the layer's structure. The general formula of LDH is [M 2+ 1−x M 3+ x (OH) 2 ](A n− ) x/n •mH 2 O, where M 2+ and M 3+ represent the divalent and trivalent metallic cations, respectively; A n− is an exchangeable n-valent anion, and x is equal to the value of the molar ratio M 3+ /(M 2+ + M 3+ ); and m is the number of interlayer water molecules [13,14]. Because of this structure, LDHs can effectively absorb the HCl formed during the dehydrochlorination of PVC and hinder the autocatalytic thermal decomposition reactions [15,16].…”