Abstract
Organic ultraviolet (UV) ray absorbents have been used as sunscreen materials, but may pose a safety problem when used at high concentration. In order to prevent direct contact of organic UV ray absorbent to the human skins organic UV absorbent such as 4,4`-diaminostilbene-2,2`-disulfonic acid (DASDSA) was intercalated into Zn2Al layered double hydroxide (Zn2Al-LDHs) by coprecipiation reaction. However, organic UV absorbents incorporated in LDH are easily deintercalated by the anion exchange reaction with carbonate ion since the selectivity of ion exchange of carbonate is quite higher. In order to depress the deintercalation of organic UV absorbent molecules from Zn2Al-LDH layer, the Zn2Al-LDH/UV-absorbing molecules could be coated with amorphous silica.
