Layered Yttrium Hydroxide as a Host for Enhancing the UV‐Protective Capacity and Photostability of Benzophenone‐5

Layered yttrium hydroxide (LYH) was explored as a host material for a highly efficient organic UV‐absorber, 2‐hydroxy‐4‐methoxybenzophenone‐5‐sulfonic acid (BP5), with the intercalation of BP5 anions into the interlayer galleries of LYH. On the basis of the powder X‐ray diffraction (XRD) pattern and Infrared (IR) spectra of the resulting BP5‐LYH hybrid, it was suggested that the double aromatic rings of BP5 anion are arranged parallel to the hydroxocation layers in the interlayer space in LYH. Thermogravimetry (TG) curves indicated the incomplete inclusion of BP5 anions due to the insufficiency of the lateral area of the interlayer space in LYH to accommodate the parallel arrangement of fully exchanged BP5 anions. The UV absorption band of BP5 was so broad as to absorb over the full UV range after intercalation in the LYH host. Long‐term use tests showed that BP5 was not significantly released from the LYH matrix in artificial seawater. This hybrid was well dispersed in a PVA solution to produce transparent BP5‐LYH/PVA composite UV‐filter films. The BP5‐LYH hybrid exhibited excellent photostability in PVA composites, maintaining complete UV‐filtering performance under simulated sunlight. A BP5‐LYH hybrid could therefore be a promising candidate not only as a UV‐filter that does not release BP5 into aquatic systems but also as a transparent outdoor UV‐screening polymer film whose single species covers the full UV range. Enlarged UV absorption range and improved photostability as well as no significant release of 2‐hydroxy‐4‐methoxybenzophenone‐5‐sulfonic acid (BP5) in galleries of layered yttrium hydroxide (LYH) substantiate the versatile potential of BP5‐LYH for safe UV‐absorber applications as a single species covering the entire UV range.