Abstract
Linear polystyrene chains were grown from the convex surface of two commercially available multiwall carbon nanotubes (MWCNTs) with similar diameter but different lengths. The MWCNTs were supplied from Bayer Material Scienceยฎ (purity >95%, external diameter = 13โ16 nm, length = 1โ10 ฮผm, denoted MWCNT~BMS~^95^) and FutureCarbon GmbH (purity >99%, external diameter = 15 nm, length = 5โ50 ฮผm, denoted MWCNT~FC~^99^). The MWCNTs were oxidized with nitric acid, consecutively reacted with thionyl chloride, glycol or poly(ethylene glycol), 2โbromoโ2โmethylpropionyl bromide and finally with styrene under atom transfer radical polymerization (ATRP) conditions. The content of polystyrene grafted from the surface of the MWCNTs can be controlled by adjusting the molecular weight of the poly(ethylene glycol), the initiator concentration and the monomer to carbon nanotube weight ratio. Under comparable experimental conditions, a higher amount of polystyrene is grafted from the MWCNT~BMS~^95^ than from MWCNT~FC~^99^. The difference in dimensions and the state of aggregation of the carbon nanotubes influence the grafting from polymerization reactions, where relative shorter and tightly aggregated carbon nanotubes promote higher polymerizations yields than longer and less aggregated carbon nanotubes. The increase of the viscosity of the carbon nanotube dispersion decreases the polymer grafting content. ยฉ 2010 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 48: 1035โ1046, 2010