New generation of thermally stable and conducting poly(azomethine-ester)s: nano-blend formation with polyaniline

Abstract

A new dihydroxy monomer, (E)-1-(4-(4-(4-hydroxybenzylidene)thiocarbamoylaminobenzyl)phenyl)-3-(4-hydroxybenzylidene)thiourea, was synthesized and polymerized with thiophene-2,5-dicarbonyl/terephthaloyl chloride. The structural characterization of the resulting polymers was carried out using spectral techniques (Fourier transform infrared and 1H NMR) along with a physical property investigation. Novel polyesters are readily soluble in various amide solvents and possess high molar mass of 112 × 103–133 × 103 g mol−1. The thermal stability was determined via 10% weight loss to be in the range 519–523 °C and the glass transition temperature was 286–289 °C. Electrically conducting poly(azomethine-ester)-blend-polyaniline blends were prepared using mash-blending and melt-blending techniques. Materials obtained using the conventional melt-blending approach generated an efficient conductive network compared with those produced by mash blending. Field emission scanning electron microscopy revealed a nano-blend morphology for the melt-blended system owing to increased physical interactions (hydrogen bonding and π–π stacking) between the two constituent polymers. Miscible blends of thiophene-based poly(azomethine-ester)-blend-polyaniline had superior conductivity (1.6–2.5 S cm−1) and thermal stability (T10 = 507 °C) even at low polyaniline concentration relative to reported thiophene/azomethine/polyaniline-based structures. The new thermally stable and conducting nano-blends could be candidates for various applications including optoelectronic devices. © 2012 Society of Chemical Industry