Abstract: Shell-structured particles for sunscreen applications are provided herein. A method includes selecting one or more particles to serve as a core material in a sunscreen composition, wherein each of the one or more particles comprises a band gap within a predetermined range, and wherein said selecting is based on a desired absorption spectrum of the sunscreen composition; coating the one or more particles with at least one layer of zinc oxide. A composition includes selecting one or more particles to serve as a coating layer in a sunscreen composition, wherein each of the one or more particles comprises a band gap within a predetermined range, and wherein said selecting is based on a desired absorption spectrum of the sunscreen composition; and coating one or more zinc oxide particles with the one or more selected particles.

Abstract: The purpose of the present invention is to provide: a copolymer for cosmetics, which has excellent water repellency and oil repellency even though a polyfluoroalkyl group therein has 6 or less carbon atoms; a surface treatment agent which contains the copolymer for cosmetics; a powder for cosmetics, which is treated with the surface treatment agent and has excellent water repellency and oil repellency; and a cosmetic preparation which contains the powder for cosmetics. A copolymer for cosmetics of the present invention contains: 70-90% by mass of a constituent unit (A) that is derived from a compound represented by formula (a); 2-25% by mass of a constituent unit (B) that is derived from a compound represented by formula (b); 2-25% by mass of a constituent unit (C) that is derived from a compound represented by formula (c); 0.