Noncovalent Side-Wall Functionalization of Single-Walled Carbon\nNanotubes

Abstract

A family of poly[(<i>m</i>-phenylenevinylene)-<i>co</i>-(<i>p</i>-phenylenevinylene)]s, functionalized in the\nsynthetically accessible C-5 position of the meta-disubstituted phenylene rings have been designed and\nsynthesized: they are essentially poly{(5-alkoxy-<i>m</i>-phenylenevinylene)-<i>co</i>-[(2,5-dioctyloxy-<i>p</i>-phenylene)vinylene]} (PA<i>m</i>PV) derivatives. A range of these PA<i>m</i>PV polymers have been prepared both (1) by the\npolymerization of O-substituted 5-hydroxyisophthaldehydes and (2) by chemical modifications carried\nout on polymers bearing reactive groups at the C-5 positions. PA<i>m</i>PV polymers solubilize SWNT bundles\nin organic solvents by wrapping themselves around the nanotube bundles. PA<i>m</i>PV derivatives which\nbear tethers or rings form pseudorotaxanes with rings and threads, respectively. The formation of the\npolypseudorotaxanes has been investigated in solution by NMR and UV/vis spectroscopies, as well as on\nsilicon oxide wafers in the presence of SWNTs by AFM and surface potential microscopy. Wrapping of\nthese functionalized PA<i>m</i>PV polymers around SWNTs results in the grafting of pseudorotaxanes along\nthe walls of the nanotubes in a periodic fashion. The results hold out the prospect of being able to construct\narrays of molecular switches and actuators.