Functionalization of Multi-Walled Carbon Nanotubes by Electrografting of Polyacrylonitrile Petar Petrov,* a Xudong Lou, Christophe Pagnoulle, Christine Je ´ro ˆme, Ce ´dric Calberg, Robert Je ´ro ˆme* Center for Education and Research on Macromolecules (CERM), University of Lie `ge, Sart-Tilman, B6, 4000 Lie `ge, Belgium Fax: (þ32) 4-3663497; E-mail: rjerome@ulg.ac.be Received: February 9, 2004; Revised: March 8, 2004; Accepted: March 8, 2004; DOI: 10.1002/marc.200400055 Keywords: carbon nanotubes; dispersions; electrochemistry; electropolymerization; surfaces Introduction As a result of their unique architecture and remarkable mechanical and electrical properties, [1,2] carbon nanotubes (CNTs) [3] have great potential that remains, however, un- exploited because of poor dispersibility in liquids and problems of processability. Major efforts have, therefore, been devoted towards any modification of the CNTs that could improve their handling. [4,5] Typically, chemical modification of CNTs is based on severe oxidation processes that often damage the tubes. [5] Mild and single-step electrochemical modification of CNTs is a valuable alternative to the oxidative treatment. There are several reports in the scientific literature on the elec- trochemical functionalization of CNTs by electroreduction of diazonium salts, [6–8] and on the halogenation of MWNTs by electrolysis. [9] However, the grafting of polymers instead of low-molecular-weight compounds onto CNTs by an electrochemical process is a possible strategy for dispersing CNTs in polymer matrices and improving the mechanical properties of CNT-based nanocomposites. For the past few years, we have been interested in the electrografting of insulating polymer films onto cathodic surfaces, for example, nickel and glassy carbon, provided that the potential and solvent are properly selected. [10–15] These films are designated as ‘‘grafted films’’, because they have the unique property of remaining attached to the electrode surface even when they are prepared and kept in a solvent in which the polymer is highly soluble. The extension of this technique to CNTs has been explored with acrylonitrile as monomer. This communication aims at reporting the functionaliza- tion of multi-walled carbon nanotubes (MWNTs) by the electropolymerization of acrylonitrile. Experimental Part Commercially available carbon vapour deposition (CVD) MWNTs (supplied by ‘‘Nanocyl S.A.’’ Belgium; up to 50 mm Summary: Multi-walled carbon nanotubes (MWNTs) have been successfully modified with polyacrylonitrile (PAN) by a cathodic electrochemical process. The surface-modified MWNTs afforded are then dispersible in good solvents for PAN, such as N,N-dimethylformamide (DMF). Collected from a dilute dispersion, these MWNTs are essentially disen- tangled, as confirmed by transmission electron microscopy (TEM) analysis. From the differential scanning calorimetry (DSC) traces for polyacrylonitrile and polyacrylonitrile- grafted MWNTs, the maximum grafting ratio is estimated at 0.28. Electrochemical grafting of polyacrylonitriles onto the surface of multi- walled carbon nanotubes. Macromol. Rapid Commun. 2004, 25, 987–990 DOI: 10.1002/marc.200400055 ß 2004 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim Communication 987 a Permanent address: Institute of Polymers, Bulgarian Academy of Sciences, ‘‘Akad. G. Bonchev’’ 103A, 1113 Sofia, Bulgaria; E-mail: ppetrov@polymer.bas.bg.