New thermally stable polyesters based on 2,5-pyridinedicarbonyl dichloride and aromatic diols: Synthesis and characterization Hossein Nasr Isfahani a , Khalil Faghihi b, * a Faculty of Chemistry, Shahrood University of Technology, Shahrood, Iran b Organic Polymer Chemistry Research Laboratory, Department of Chemistry, Faculty of Science, Arak University, Arak 38156, Iran Received 2 December 2008 Abstract Six new thermally stable polyesters (4a–f) were synthesized through the solution polycondensation reaction of 2,5-pyridine dicarbonyldichloride (2) with six aromatic diols in N,N 0 -dimethyl acetamide (DMAc) solution and in the presence of pyridine as a base. The polycondensation reactions produce a series of new polyesters (4a–f) in high yields, and inherent viscosity between 0.30 and 0.55 dL/g. The resulting polyesters were characterized by elemental analysis, viscosity measurements, thermal gravimetric analysis (TGA and DTG), solubility test, Fourier transform infrared (FT-IR) spectroscopy and gel permeation chromatography (GPC). # 2009 Khalil Faghihi. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. Keywords: High performance polymers; Polyesters; Pyridyl moiety High-performance-heat resistance polymers such as aromatic polyimides, poly(amide-imide)s, polyamides and polyesters are characterized by their excellent balance of thermal and mechanical properties which makes them useful materials for engineering applications. However, these polymers particularly those with para-substituted rings exhibit poor processability and limited solubility in organic solvents. Therefore, many efforts have been made to create structurally modified aromatic polymers having increased solubility and processability with retention of their high thermal stability [1–9]. In this paper the synthesis of a new series of polyesters (4a–f) containing pyridyl moieties in the main chain was reported by polycondensation reaction of 2,5-pyridinedicarbonyl dichloride (2) with six different aromatic diols (3a–f) in N,N 0 -dimethyl acetamide (DMAc) solution and in the presence of pyridine as a base. These polymers have a heterocyclic aromatic ring such as pyridyl moiety in the main chain that cases better solubility in organic solvents in compared to aromatic polyesters. 1. Experimental All chemicals were purchased from Merck Chemical Co. (Germany) and Aldrich (USA). Fourier transform infrared (FT-IR) spectra were recorded on Galaxy series FT-IR 5000 spectrophotometer (England) as KBr pellets. www.elsevier.com/locate/cclet Available online at www.sciencedirect.com Chinese Chemical Letters 20 (2009) 885–888 * Corresponding author. E-mail address: k-faghihi@araku.ac.ir (K. Faghihi). 1001-8417/$ – see front matter # 2009 Khalil Faghihi. Published by Elsevier B.V. on behalf of Chinese Chemical Society. All rights reserved. doi:10.1016/j.cclet.2009.01.014