1. Introduction Polyaniline (PANI) has been one of the most stud- ied electrically conducting polymers. This is mainly because of its simple doping-dedoping REDOX chemistry, ease of synthesis, relatively inexpensive production and ability to yield nanostructured mate- rials of different morphologies. There are different means for obtaining PANI including a chemical, an electrochemical and recently introduced a micro- wave (MW) assisted methodology [1–3]. Over the last decade the chemical approach i.e. the oxidative polymerization of aniline has been used for the synthesis of wide variety of products with different morphologies and physical and chemical properties [4–14]. The specific characteristics make PANIs applicable in various fields such as gas sen- sors, biosensors, actuators, anticorrosive coatings, electronic devices etc. [1, 2]. Some of syntheses have been performed at medium or high pH (pH > 4) com- pared to standard, relatively low pH conditions (pH < 2.5) [15, 16]. The standard low pH synthesis in an acidic medium using 1 M HCl for instance yields morphologically featureless and highly conductive PANIs. On the other hand it has been shown that higher pH values very often favour self-assembly of well-defined, but less conductive supramolecular 745 Self-assembly of nanostructures obtained in a microwave-assisted oxidative polymerization of aniline M. R. Gizdavic-Nikolaidis 1,2 , M. M. Jevremovic 3 , M. C. Allison 1 , D. R. Stanisavljev 2 , G. A. Bowmaker 1 , Z. D. Zujovic 1,4,5* 1 School of Chemical Sciences, The University of Auckland, Private Bag 92019, 1142 Auckland, New Zealand 2 Faculty of Physical Chemistry, Studentski Trg 12-16, 11001 Belgrade, Serbia 3 Nuclear Facilities of Serbia, 12–14 Mike Petrovica Alasa, Vinca, 11351 Belgrade, Serbia 4 Institute of General and Physical Chemistry, Studentski Trg 12–16, 11001 Belgrade, Serbia 5 MacDiarmid Institute for Advanced Materials and Nanotechnology, Victoria University of Wellington, 6140 Wellington, New Zealand Received 9 April 2014; accepted in revised form 26 May 2014 Abstract. For the first time, microwave assisted aniline oxidative polymerization is performed in the presence of acetic acid (CH 3 COOH) and ammonium hydroxide (NH 4 OH) at different microwave power levels. The reaction system is kept at constant temperature of 24±1°C. The products are investigated by Fourier Transform Infrared Spectroscopy (FTIR), Raman, solid-state Nuclear Magnetic Resonance (NMR) and Electron Paramagnetic Resonance (EPR) spectroscopies. EPR signals in polyaniline (PANI) originate from the polarons formed upon protonation and doping by acid. The microwave radiation causes an increase in the spin concentration which is slightly more evident for 8 W than for 93 W. The morphol- ogy is investigated by using scanning electron microscopy (SEM). SEM micrographs revealed the formation of nanorods (in the presence of CH 3 COOH) and nanospheres (in the presence of NH 4 OH). FTIR, Raman and solid-state NMR spectro- scopies indicate the presence of PANI and aniline oligomers. X-ray Diffraction (XRD) measurements showed the presence of well-ordered structures. Keywords: polymer synthesis, molecular engineering, microwave-enhanced, self-assembly, polyaniline, nanomaterials eXPRESS Polymer Letters Vol.8, No.10 (2014) 745–755 Available online at www.expresspolymlett.com DOI: 10.3144/expresspolymlett.2014.77 * Corresponding author, e-mail: z.zujovic@auckland.ac.nz © BME-PT