Polymer composites containing variable amounts of multiwalled carbon nanotubes (MWNTs) have been prepared using solution dispersion and melt-shear mixing. Various polymer composites with 1 wt % MWNTs have been found to dissolve homogeneously in organic solvents. The amount of polymer coated or wrapped MWNTs dissolved in the solution was quantified using UV-vis absorbance at 500 nm and the concentration ratio of [MWNTs] solution /[MWNTs] composite was close to 1. A nonspecific polymer adsorption through multiple-weak molecular interactions of CH groups with MWNTs in the composites has been identified through FTIR spectroscopy. The composites of polybutadiene with different wt % of MWNTs showed slight changes in the CH bending vibrations, indicating the presence of intermolecular CH-π interactions. The dissolution of various polymer composites containing low concentration of MWNTs in organic solvents was attributed to polymer coating on the MWNTs via noncovalent and nonspecific CH-π interactions. The dissolution of MWNTs in organic solvents using common polymers used in this study indicates that the coating or wrapping is a general phenomenon occurring between polymers and carbon nanotubes.

Hairy polymers from MWNTS: Surface‐initiated polymerization (SIP) of methyl methacrylate (MMA) and styrene (S) has been performed from the surfaces of multiwalled carbon nanotubes (MWNTs) by using a covalently attached atom‐transfer radical initiator. The initiator is grafted to the surface of the MWNTs through carboxy groups. Hairy homo, block, and copolymers consisting of PS and PMMA brushes can then be grown from the surface of the MWNTs (see scheme).

Functionalization of carbon nanotubes through surface modification has attracted significant interest recently. [1][2][3][4][5] Covalent and noncovalent functionalization strategies involving reactions of organic or polymeric molecules onto carbon nanotubes have primarily focused on dispersion or dissolution properties. Incorporation of light absorbing antenna chromophores through a covalent linkage with the extended π electrons of a carbon nanotube would constitute an ideal supramolecular nanoassembly for generating singlet excited energy and its conversion to chemical energy. Porphyrins are one such class of molecules used in assemblies of donor-acceptor materials in molecular electronics and photovoltaic devices. 6 Several fullerene-based molecular systems with covalently linked porphyrins and metalloporphyrins have been synthesized; their interesting photoinduced electron-transfer processes have been studied. 6-8 Noncovalent interaction of metalloporphyrins and freebase porphyrins with single-wall carbon nanotubes (SWNTs) has been used for dispersion and also for separation of semiconducting and metallic tubes. 9,10 Recently, a noncovalently interacting donoracceptor system consisting of an anionically functionalized porphyrin and a cationically functionalized pyrene stacked on SWNTs has been shown to exhibit electron-transfer properties. 11 A donoracceptor system with a covalent linkage between the light-harvesting antenna and the acceptor reaction center could enhance the efficiency of photoinduced electron transfer and energy transfer. Supramolecular structures consisting of covalently grafted porphyrins to carbon nanotubes have not been synthesized so far as an efficient donor-acceptor system. In this communication, we report the synthesis of meso-substituted porphyrin-grafted carbon nanotubes ((por) n -g-CNTs), including multiwalled nanotubes ((por) n -gMWNTs) and SWNT ((por) n -g-SWNTs), and the study of their photoinduced electron-transfer properties.We used surface-bound carboxylic acid groups (∼1 mol %) of MWNTs and SWNTs to attach a functional porphyrin, 5-phydroxyphenyl-10,15,20-tritolylporphyrin (por-OH). 12 HiPco SWNTs were purified using stepwise wet-air oxidation and shortened using a sulfuric acid/nitric acid (3:1) treatment. First, carbon nanotubes treated with thionyl chloride were reacted with excess por-OH in toluene in the presence of triethylamine at 100°C for 24 h under a pure nitrogen atmosphere. To remove the unreacted por-OH, the tubes were washed thoroughly with plenty of methanol, followed by a small amount of acetic acid and triethylamine, and finally with tetrahydrofuran (THF). The (por) n -g-CNTs were then dried at 40°C for 5 h under vacuum.The FTIR spectrum of the porphyrin-attached carbon nanotubes (Scheme 1) showed characteristic vibrations of pyrrole, methyl, and aromatic groups centered at 1200, 2922, and 3010 cm -1 , respectively. The quantity of porphyrin attached to the surface was determined from thermogravimetric analysis (TGA), which showed a gradual weight loss star...