US Patent No. 9,168,218 B2; L’Oréal has patented a composition that contains photoluminescent polymer (PLP), which is a polyester synthesized from a multifunctional monomer containing two carboxylic acid groups and a functional moiety comprising a carboxylic acid group or a hydroxyl group, and a diol. The photoluminescent polymer has grafted thereon or incorporated into the polymer backbone, an amino acid or an amino acid derivative that is S-benzyl-L-cysteine. The composition also contains s...