Synthesis and Characterization of N- and O-Alkylated Poly[aniline-co-N-(2-hydroxyethyl) aniline] Leyla Shadi, 1 Homa Gheybi, 1 Ali Akbar Entezami, 1 Kazem D. Safa 2 1 Laboratory of Polymer, Faculty of Chemistry, University of Tabriz, Tabriz, Iran 2 Laboratory of Organo Silicone, Faculty of Chemistry, University of Tabriz, Tabriz, Iran Received 21 November 2010; accepted 8 July 2011 DOI 10.1002/app.35218 Published online 26 October 2011 in Wiley Online Library (wileyonlinelibrary.com). ABSTRACT: Poly[aniline-co-N-(2-hydroxyethyl) aniline] was synthesized in an aqueous hydrochloric acid medium with a determined feed ratio by chemical oxidative polymer- ization. This polymer was used as a functional conducting polymer intermediate because of its side-group reactivity. To synthesize the alkyl-substituted copolymer, the initial copol- ymer was reacted with NaH to obtain the N- and O-anionic copolymer after the reaction with octadecyl bromide to pre- pare the octadecyl-substituted polymer. The microstructure of the obtained polymers was characterized by Fourier trans- form infrared spectroscopy, 1 H-NMR, and X-ray diffraction. The thermal behavior of the polymers was investigated by thermogravimetric analysis and differential scanning calo- rimetry. The morphology of obtained copolymers was stud- ied by scanning electron microscopy. The cyclic voltammetry investigation showed the electroactivity of poly [aniline-co-N-(2-hydroxyethyl) aniline] and N and O-alky- lated poly[aniline-co-N-(2-hydroxyethyl) aniline]. The con- ductivities of the polymers were 5  10 5 S/cm for poly[aniline-co-N-(2-hydroxyethyl) aniline] and 5 10 7 S/ cm for the octadecyl-substituted copolymer. The conductiv- ity measurements were performed with a four-point probe method. The solubility of the initial copolymer in common organic solvents such as N-methyl-2-pyrrolidone and dime- thylformamide was greater than polyaniline. The alkylated copolymer was mainly soluble in nonpolar solvents such as n-hexane and cyclohexane. V C 2011 Wiley Periodicals, Inc. J Appl Polym Sci 124: 2118–2126, 2012 Key words: conducting polymers; conjugated polymers; functionalization of polymers; graft copolymers; polymer synthesis and characterization INTRODUCTION During the past 3 decades, a wide variety of electri- cally conducting polymers have been studied because of their exclusive physical properties. Among the con- ducting polymers, including polyaniline, polypyrrole, polythiophene, and polyacetylene, polyaniline has been studied extensively for its environmental stability in the conducting form, easiness in synthesis, low-cost synthesis, unique redox properties, and reasonable conductivity. 1 These properties are favorable for its applications in gas sensing, 2–4 solar cells, 5,6 electro- magnetic interference shielding, 7,8 antistatic coating, 9 and organic light-emitting diodes. 10–12 However, for a long time, it has been revealed to be difficult to pro- cess, having no solubility and melting point, likely because of its intrinsic stiffness. Numerous methods have been developed to overcome these shortcomings. These include • The postprocessing technique. 13 • Emulsion polymerization. 14–16 • Preparation of the composites or blends. 17–19 • Copolymerization. 20,21 • The incorporation of side groups into the main chain. 22–25 • The grafting of electron-donating groups, such as alkyl groups. 26–28 Among these methods, important chemical modi- fications have been the copolymerization and addi- tion of saturated hydrocarbon alkyl side chains to the polymeric backbone. These approaches have been successfully applied to solubilize the intractable polyaniline with the copolymerization of aniline with other monomers and the incorporation of alkyl groups with various sizes. Zheng et al. 26 reported the incorporation of alkyl side chains into the polya- niline backbone. They showed that the incorporation of alkyl substituents in various sizes could control the chemical structure, innovate in its tractability for processing applications, and modify the physical properties of this conjugated polymer. In addition, the improvement of solubility in common organic solvents for products with more than eight carbons on the side chain was proven. Cataldo and Maltese 29 made a complete investigation of the thermal stability of PANI and its alkyl and N-alkyl derivatives in the undoped state, known as emeraldine base, and in the doped state, where camphorsulfonic acid (CSA) was used as a dopant for its applications in a gas-sensing device. Recently, the synthesis and characterization of Correspondence to: A. A. Entezami (aaentezami@yahoo. com or aentezami@tabrizu.ac.ir). Journal of Applied Polymer Science, Vol. 124, 2118–2126 (2012) V C 2011 Wiley Periodicals, Inc.