Carbon 41 (2003) 1391–1395 Electrical properties of composites based on conjugated polymers and conductive fillers a a, b b * I.A. Tchmutin , A.T. Ponomarenko , E.P. Krinichnaya , G.I. Kozub , b O.N. Efimov a Enikolopov Institute of Synthetic Polymeric Materials, RAS, Moscow 117393, Russia b Institute of Problems in Chemical Physics, RAS, Chernogolovka, Russia Received 13 August 2002; accepted 31 January 2003 Abstract Composite materials based on undoped conjugated polymers and conductive filler were synthesized and their electrophysical and electrochemical properties were investigated. Conjugated polymers such as polyaniline (PANI), polyacetylene (PA) and typical polymer dielectric, polypropylene (PP) were used as matrices. Graphite and single-walled nanotubes were used as conductive fillers. The investigation of the dependencies of conductivity on filler concentration show that in contrast to PP and PANI, PA becomes conductive due to injected charge carriers from filler particles. This conclusion is supported by investigated dependencies of composite conductivity on temperature and time during aging and on cyclic voltammetry data. It was shown that a conjugated polymer matrix allows composite materials with new electrophysical and electrochemical properties to be produced.  2003 Elsevier Science Ltd. All rights reserved. Keywords: A. Carbon composites; Carbon nanotubes; Natural graphite; B. Heat treatment; D. Electrical properties 1. Introduction erties. The principal tasks were to determine the possibility of such a matrix being doped by charge carriers from filler Synthesis and investigation of electrophysical properties particles, and the filler concentration starting from which of polymer composites based on polyconjugated matrices the composites demonstrate essential conductivity that is and graphitized carbon species, including single-walled important both in theoretical and practical aspects. nanotubes (SWNT), are currently very popular topics in the field of materials science and, therefore, are of theoret- ical and practical interest. For example, even now 2. Experimental nanotube–polymer composites are regarded as promising materials for use in lithium batteries, supercapacitors, Conjugated polymers such as polyaniline (PANI), poly- actuators, sensors, etc. It follows from various publications acetylene (PA) and typical polymer dielectric, poly- that the electrical, thermal, mechanical and other properties propylene (PP) were used as matrices. PA was prepared as of composites based on graphitized carbon fillers, par- a powder by polymerization of prepurified and desiccated ticularly SWNT, are dependent on their preparation pro- acetylene on the Ziegler–Natta catalyst of the Al(C H ) – 2 5 3 cedure and correlate with their structure [1]. Ti(OC H ) composition. The method of PA synthesis was 4 9 4 The aim of the present work was to synthesize compo- described in detail in Ref. [2]. site materials based on undoped conjugated polymers and PANI was prepared as a product of oxidation poly- conductive filler—graphite and carbon nanotubes—and to merization of aniline. The reaction temperature was in the investigate their electrophysical and electrochemical prop- range 0–20 8C. Polyaniline chloride was filtered, washed by distilled water (pH57), alcohol and acetone, and then dried at 600 8C under dynamic vacuum for 3–5 h. The *Corresponding author. Fax: 17-95-333-9470. E-mail address: anapon@ispm.ru (A.T. Ponomarenko). PANI base was prepared by treating PANI with 3% 0008-6223 / 03 / $ – see front matter  2003 Elsevier Science Ltd. All rights reserved. doi:10.1016 / S0008-6223(03)00067-8