A study of the chemical and the enzyme-catalyzed oxidative polymerization of aromatic diamine bearing chlor substituents, pursuant to structural, thermal and photophysical properties

Feyza Kolcu^a,b, Ismet Kaya^a

Polymer Synthesis and Analysis Laboratory, Department of Chemistry, Çanakkale Onsekiz Mart University, 17020 Çanakkale, Turkey.

Abstract

2,5-Dichloro-p-phenylenediamine (ClPDA) is a member of aromatic diamines. This descriptive study sought the oxidative polymerization of ClPDA with hydrogen peroxide using the enzyme-catalyzed and the chemical oxidative ways for the syntheses of P-ClPDA-E and P-ClPDA-O, respectively. Neutral ClPDA was easily oxidized to the polymers composed of ortho-coupled constitutional moieties with lower optical and electrochemical band gaps than those of ClPDA using two polymerization routes. The elucidation of molecular structures obtained from the enzyme-catalyzed and the chemical oxidative polymerization of ClPDA were carried out by the FT-IR, UV–Vis, ¹H NMR and ¹³C NMR techniques, concluded with the ladder-type and the perrnigraniline-type polymer formation as a result of two different polymerization processes. Solvent effects in selected polar solvents on the optical properties of P-ClPDA-E and P-ClPDA-O were also analyzed. Thermal and electrochemical properties of the products were fulfilled using TG-DTA-DSC and cyclic voltammetry (CV) techniques, respectively. The number of average molecular weight of P-ClPDA-E was found to be higher than that of P-ClPDA-O. The degradation of ladder-type structure of P-ClPDA-E with higher M_w value started at higher temperatures compared to P-ClPDA-O, which was composed of benzenoid and quinoid units. In response to the excitation of UV light, only P-ClPDA-E radiated blue light with high intensity and a quantum yield of 23% in DMF depending on photoluminescence measurement. Scanning Electron Microscopy (SEM) views set a precedent for the agglomerates of particles. The enzyme-catalyzed oxidation of ClPDA resulted in the formation of nanospheres of P-ClPDA-E. In course of a change in the polymerization method, the morphology of the chemical oxidative polymerized ClPDA (P-ClPDA-O) was seen spongy with some pores.

Graphical abstract

Keywords : Methane oxidation, Selenate reduction, Membrane biofilm batch reactor, Mixed consortium, Wastewater treatment.