New low-band gap polyurethanes containing azomethine bonding: Photophysical, electrochemical, thermal and morphological properties

Abstract

In this paper, a series of new Schiff bases with different substituents were prepared via condensation reaction of vanillin and different diamines. These monomers were converted to polyurethane derivatives using aliphatic and aromatic diisocyanates as co-monomer via step-polymerization reactions. Photophysical, electrochemical, thermal and morphological properties of these compounds were also clarified. Photophysical properties of the compounds were determined by using UV-vis and photoluminescence (PL) spectroscopy. Thermal stability and degradation behavior of Schiff bases and their poly(azomethine-urethane) derivatives were investigated by using TG-DTA technique. Also, thermal transitions properties of polyurethanes containing azomethine linkage were clarified using DSC technique. Mechanical and morphological properties of poly(azomethine-urethane)s were also determined by using DMA and SEM, respectively. Morphological photographs showed that poly(azomethine-urethane)s have different particle sizes and consist of semi crystalline particles. Electrochemical properties of the materials were investigated by using cyclic voltammetry (CV). Electrochemical results showed that PAMUs have electrochemical band gap below 2.0 eV. (C) 2015 Taiwan Institute of Chemical Engineers. Published by Elsevier B.V. All rights reserved.