Highly Enhanced Electrical Conductivity and Thermal Stability of Polythiophene/Single-walled Carbon Nanotubes Nanocomposite

Herein, we synthesized and characterized polythiophene/single-walled carbon nanotubes nanocomposite. Thiophene (Th) and 2-(2-thienyl) pyrrole (TP) were selected as interfacial modifiers for a SWNT-poly(Th-TP) nanocomposite. The electrical conductivity and thermal stability can be dramatically improved by in-situ polymerization of a thin layer of self-doped conducting polymer around and along the single-walled carbon nanotubes (SWNTs) beside the bulk polymer. The resulting cable-like morphology of the SWNT-poly(Th-TP) composite structure was characterized with Fourier transform infrared (FTIR), ultraviolet-visible spectroscopy (UV-Vis), field emission scanning electron microscopy (FE-SEM), thermogravimetric analysis (TGA), X-ray diffraction (XRD), transmission electron microscopy (TEM) and Raman spectroscopy. Also, the morphology of the film was investigated using a scanning tunneling microscopy (STM). The characterization of the molecular structure has indicated that thiophene and TP molecules are adsorbed onto the surface of SWNTs to polymerize and SWNTs have been used as the core in the formation of a hybrid SWNTpoly(Th-TP) composite. Transmission electron microscopy analysis revealed that in the SWNT-poly(Th-TP) composite, SWNT constitutes the core and poly(Th-TP) acts as the shell. TGA data confirm that the presence of SWNT in the composite is responsible for the high thermal stability of the whole material in comparison with pure poly(Th-TP). The standard four-point-probe method was utilized to measure the conductivity of the samples. The conductivity through SWNT-poly(Th-TP) is as high as 38 Scm-1, well above the normal conductivity value of bulk poly(Th-TP) films (~1.67 × 10-1 Scm-1). In addition numerous physical properties of the nanocomposite were measured and the obtained results are discussed