Effects of phenylene ring derivatization of polyaniline on its optical properties

Abstract Thin films of polyaniline (PANI) and PANI derivatives have been prepared by spincoating method with alkoxy substitutions at the phenyl rings for the study of derivatization effects on the optical properties. A proper analysis of the resulted UV–visible spectra by taking into account the reflection loss clearly indicates systematic blue-shift of the PANI absorption maximum with longer alkoxy substituents as well as increasing suppression of its absorption tail. It is further found that in addition to improved film quality due to increased solubility, the alkoxy substitutions also result in remarkable enhancement of optical damage threshold of PANI allowing its non-linear optical application with higher light intensity. The result of THG measurement on poly(ethoxyaniline) (E-PANI) does not show significant difference of χ (3) from those reported for PANI and poly(methoxyaniline) (M-PANI). These results suggest the desirability of a further study on the optimal structural modification of PANI for its potential photonic applications.