Researchers at the University of Tsukuba, Japan, have developed a method for synthesizing polyaniline—a conductive polymer exhibiting golden luster—marking the first successful attempt globally. The reflection spectrum of this polyaniline resembles that of metallic gold.

Polyaniline, a conductive polymer typically synthesized in water and appears dark green, exhibits different properties based on its synthesis and processing conditions. The research team involved in the study, now published in Next Materials, successfully synthesized polyaniline, with golden luster, in two stages.

In the first stage, fine particles were prepared using short-time electrochemical polymerization, high-voltage spark treatment and other methods, and in the second stage, chemical polymerization was applied. Notably, the electrical conductivity of this golden polyaniline is lower than that of polyacetylene, making it unsuitable for transmitting large currents. However, this golden polyaniline has the potential to revolutionize the electronics sector due to its applicability in micro-organic semiconductor thin-films and other similar devices.

The reflectance spectrum of the newly developed golden polyaniline is similar to that of gold. The metallic luster of polyacetylene, a conventional conductive polymer, is based on the plasma reflection of free electrons due to the high density of π-electrons within the molecule. In contrast, the metallic luster of the newly synthesized gold-colored polyaniline is attributed to a combination of polarons, which are carriers responsible for conductivity, and surface luster.