| 초록 |
Carbon nanotubes(CNTs) have attracted an enormous attention over the past decade because of their unique electronic, thermal, optical, and mechanical properties. These unique properties of carbon nanotubes offer a number of potentially exciting applications such for field emission display device. One of the primary obstacles in those applications is that carbon nanotubes form aggregates in nearly all solvent systems due to the substantial van der Waals attractions between tubes. To prevent this undesirable CNTs aggregation, various surfactants have been used for the dispersion of CNTs. In this study, amphiphilic T-shaped oligothiophene-g-PEG copolymer is used as the polymeric surfactant for the solubilization of nanotubes. Different lengths of oligothiophenes are hydrophobic-rigid backbone and different molecular weight of PEG is hydrophilic-flexible graft. Poly(ethylene glycol) methyl ether 3-thiophene acetate was synthesized by DCC coupling of 3-thiopheneacetic acid and poly(ethylene glycol) methyl ether. It was then successively brominated at the 1,4 position with N-bromosuccinimide followed by Stille coupling with 2-(tributylstannyl) thiophene for the preparation of different length of oligothiophene at the end of poly(ethylene glycol) monomethyl ether. Synthesized T-shaped oligothiophene-g-PEG copolymers were characterized by NMR and SEC. The solubilization of nanotubes by the thiophene-PEG surfactant was compared to that by the commercial surfactant SDS (sodium dodecyl sulfate) by using TEM, AFM and TGA. Furthermore, to theoretically analyze these results, we calculated the binding energy of surfactant onto the nanotubes using a molecular mechanics simulation.
|
