Oligo(3-methoxythiophene)s as Water-Soluble Dyes for Highly Lustrous Gold- and Bronze-like Metal-Effect Coatings and Printings.

To overcome various shortcomings associated with commercial metal-effect gloss paints containing metal flakes, we examine possible candidates to be used as novel organic-only metal-effect dyes for both paints and inks. Recently, one of the authors developed a potential candidate (ClO4 --doped oligo(3-methoxythiophene)), but the required solvent was not industrially acceptable and the cured paint displayed low glossiness. Herein, we synthesized and characterized Cl--doped oligo(3-methoxythiophene) dyes that were water-soluble and displayed a highly lustrous gold- and bronze-like hue upon curing. Additionally, we found that films derived from these oligomers form extremely regular and compact edge-on lamella crystallites through self-organization; these films also display a highly glossy metallic appearance due to the extremely high optical constants of the crystallites. These as-prepared films were easily soluble in water, but we also found that the films become insoluble in water upon dehydration, making industrial implementation feasible.