Synthesis and characterization of single wall carbon nanotube-grafted poly(3-hexylthiophene) and their nanocomposites with gold nanoparticles

• Ternary nanocomposites were synthesized by chemical grafting or physical mixture.
• Nanocomposites of poly(3-hexylthiophene), carbon nanotubes and gold nanoparticles.
• Thermal, optical and structural characteristics were investigated.
• The polymer/nanotube interaction affects the size and shape of the gold nanoparticles.

Single-wall carbon nanotubes (SWCNTs) were functionalized via the Prato reaction, by using a combination of N-methylglycine and 2-thiophenecarboxaldehyde (2T) or 3-thiophenecarboxaldehyde (3T). Pristine SWCNTs or functionalized SWCNTs were then reacted with 3-hexylthiophene (3HT) in the presence of FeCl3 to produce a composite (P3HT/SWCNT) or copolymers (P3HT-2T-SWCNT and P3HT-3T-SWCNT), containing 3-hexylthiophene units as the main chain and carbon nanotubes as side groups. After that, gold nanoparticles (AuNPs) were synthesized using a two-phase, one-pot reaction involving the reduction of HAuCl4 by NaBH4, in the presence of P3HT, P3HT/SWCNT, P3HT-2T-SWCNT or P3HT-3T-SWCNT. This approach generated nanocomposites where AuNPs were stabilized directly with P3HT- or P3HT-containing SWCNTs. The characteristics of the ternary nanocomposites were investigated using UV–vis and fluorescence spectroscopy, thermogravimetric analysis, X-ray diffraction and high-resolution transmission electron microscopy.