Nano-Hybrids Based on Surface Modified Reduced Graphene Oxide Nanosheets and Carbon Nanotubes and a Regioregular Polythiophene

Abstract

<br /> <br /> The multi-walled carbon nanotubes (CNTs) and reduced graphene oxide (rGO) nanosheets were functionalized with 2-hydroxymethyl thiophene (CNT-<em>f</em>-COOTh) and 2-thiophene acetic acid (rGO-<em>f</em>-TAA) and grafted with poly(3-dodecylthiophene) (CNT-<em>g</em>-PDDT and rGO-<em>g</em>-PDDT) to manipulate the orientation and patterning of crystallized regioregular poly(3-hexylthiophene) (P3HT). Distinct nano-hybrid structures including double-fibrillar (5.11−5.18 S/cm), shish-kebab (2.19−2.28 S/cm), and stem-leaf (6.96−7.51 S/cm) were developed using modified CNTs and P3HT. The most effective parameter on morphology of donor-acceptor supramolecules was the surface functionalization and grafting. The electrical conductivities of supramolecules based on P3HT and rGO, rGO-<em>f</em>-TAA, and rGO-<em>g</em>-PDDT ranged in 3.81−3.87, 3.91−3.95, and 10.67−10.70 S/cm, respectively. P3HT chains preferred to interact with their thiophene rings with bared rGO and CNT surfaces, resulting in a conventional face-on orientation. In P3HT/rGO-<em>f</em>-TAA and P3HT/CNT-<em>f</em>-COOTh supramolecular nanostructures patterned with P3HT, the orientation of P3HT chains changed from face-on to edge-on, originating from the strong interactions between the hexyl side chains of P3HTs and functional groups. Nano-hybrids based on grafted rGO demonstrated a patched-like morphology composed of flat-on P3HTs with main backbones perpendicular to the substrate. Based on the ultraviolet-visible and photoluminescence analyses, the flat-on orientation was the best for P3HT chains assembled onto CNT and rGO, which was acquired for CNT-<em>g</em>-PDDT and rGO-<em>g</em>-PDDT nano-hybrids.