Deep eutectic solvent‐assisted synthesis of polyaniline by laccase enzyme

Abstract

Abstract BACKGROUND Deep eutectic solvents (DESs) have attracted considerable attention for many chemical applications due to their environmentally friendly characteristics, low cost and limited or no health issues. Polyaniline (PANI) has been of a great interest for many years due to its distinctive electrical and optical properties and accordingly its diverse application fields. Enzymatic synthesis of PANI offers mild and environmentally benign conditions. However, the main difficulty of the enzymatic method is the formation of undesired units in the polymer, which can be overcome by the use of templates. Thus, the reaction is guided towards the desired products. This study reports – for the first time – that DESs can be used as templates in the synthesis of polymers. RESULTS Several DESs were tested in the oxidation of aniline to form PANI by the catalytic effect of laccase and it was found that d , l ‐menthol–decanoic acid (Ment‐DA; 1:1) assisted the polymer formation. The effects of synthesis conditions such as volume concentration of Ment‐DA, laccase activity, initial concentration of aniline, pH of the medium, temperature and agitation rate on the formation of PANI were investigated. In situ doping of PANI with acids during DES‐assisted synthesis of the polymer was also carried out to provide electrically conducting PANI. The resulting polymers were characterized using their UV–visible and Fourier transform infrared spectra, electrical conductivities and morphologies. CONCLUSIONS This work introduces a new type of template for use in polymerization reactions. © 2020 Society of Chemical Industry