Surfactant‐Directed Polypyrrole/CNT Nanocables: Synthesis, Characterization, and Enhanced Electrical Properties

Abstract

We describe here a new approach to the synthesis of size‐controllable polypyrrole/carbon nanotube (CNT) nanocables by in situ chemical oxidative polymerization directed by the cationic surfactant cetyltrimethylammonium bromide (CTAB) or the nonionic surfactant polyethylene glycol mono‐p‐nonylphenyl ether (Oπ–10). When carbon nanotubes are dispersed in a solution containing a certain concentration of CTAB or Oπ–10, the surfactant molecules are adsorbed and arranged regularly on the CNT surfaces. On addition of pyrrole, some of the monomer is adsorbed at the surface of CNTs and/or wedged between the arranged CTAB or Oπ–10 molecules. When ammonium persulfate (APS) is added, pyrrole is polymerized in situ at the surfaces of the CNTs (core layer) and ultimately forms the outer shell of the nanocables. Such polypyrrole/CNT nanocables show enhanced electrical properties; a negative temperature coefficient of resistance at 77–300 K and a negative magnetoresistance at 10–200 K were observed.