Phase Separation of Polymer-Functionalized SWNTs within a PMMA/Polystyrene Blend

Phase separation of polystyrene (PS) and poly(methyl methacrylate) (PMMA) blends was used as a means to segregate PS- or PMMA-functionalized single-walled carbon nanotubes (SWNTs) in thin films. Dilute solutions (5 wt % in THF) of 1:1 PS/PMMA blends containing the functionalized nanotubes were spin cast and annealed at 180 degrees C for 12 h. Two different polymer molecular weights were used (M-n = 8000 or M-n = 22,000), and were of approximately equivalent molecular weight to those attached to the surface of the nanotubes. Nanotube functionalization was accomplished using the Cu(I)-catalyzed [3 + 2] Huisgen cycloaddition, in which alkyne-decorated nanotubes were coupled with azide-terminated polymers, resulting in polymer-SWNT conjugates that were soluble in THF. Characterization of the annealed films by scanning Raman spectroscopy, which utilized the unique Raman fingerprint of carbon nanotubes, enabled accurate mapping of the functionalized SW-NTs within the films relative to the two phase-separated polymers. It was found that nanotube localization within the phase-separated polymer films was influenced by the type of polymer attached to the nanotube surface, as well as its molecular weight. (C) 2008 Wiley Periodicals, Inc. J Polyrn Sci Part A: Polym Chem 47: 450-458, 2009