Preparation and characterization of green reflective films of polyaniline analogs containing azobenzene units

• Published in: Journal of applied polymer science 2015-01, Vol.132 (2), p.np-n/a
• Main Authors: Yamada, Hikaru, Kukino, Minoru, Wang, Zhi An, Miyabara, Ryo, Fujimoto, Nobutaka, Kuwabara, Junpei, Matsuishi, Kiyoto, Kanbara, Takaki
• Format: Article
• Language: English
• Subjects: Analogs; coatings; Color; dyes/pigments; Luster; Materials science; optical properties; Polyanilines; polycondensation; Polymers; Reflection; Refractive index; Refractivity; Surface chemistry
• ISSN: 0021-8995; 1097-4628
• DOI: 10.1002/app.41275

ABSTRACT Pd‐catalyzed polycondensation of aniline derivatives and 4,4′‐dibromoazobenzene affords polyaniline analogs containing azobenzene units. The polymers are red in solution and in thin films state, whereas they have a green luster in thick films. Substitution of 4,4′‐dibromoazobenzene for 4,4′‐dibromostilbene changes the reflection color from green to blue, whereas the introduction of a non‐conjugated unit slightly affects the reflection color. The glossiness of the film is dependent on the smoothness of the film surface. The reflectance measurements using polarized light reveal that reflection spectra correlate well with the complex refractive index (ñ = n + ik) of the film. These results confirm that the green luster can be attributed to the uniform surface reflection of the object, which has a large refractive index and absorption coefficient at around 500 nm. The polymer films exhibit good transmission of radio frequency signals owing to the lack of free electron carriers. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41275.