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 (ClO 4 – -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.

No abstract

Solution-cast coating films of perchlorate-doped oligo(3-methoxythiophene) exhibited a gold-like luster similar to that of metallic gold despite the involvement of no metals. However, the development mechanism of the luster remains ambiguous. To understand the mechanism, we performed scanning electron microscopic analysis, variable-angle spectral reflectance measurements, and ellipsometry measurements on ClO4−-doped oligo(3-methoxythiophene) cast film with a gold-like luster. The results revealed that the lustrous color of the film was not induced by the submicron-sized regular structures (structural color), nor by the high-density free electrons (reflective response based on Drude model), but by the large optical constants (refractive index and extinction coefficient) of the film, as speculated previously.

No abstract