Plasma activation of carbon nanotubes for chemical modification

A novel approach for chemical modification of carbon nanotubes was develope d, which involved radio frequency glow-discharge plasma activation, followe d by chemical reactions characteristic of the plasma-generated functional g roups. For instance, amino-dextran chains have been immobilized onto acetal dehyde-plasma-treated aligned carbon nanotubes through the formation of Sch iff-base linkages, which were further stabilized by reduction with sodium c yanoborohydride. Using the same reaction, we have also chemically grafted p eriodate-oxidized dextran chains pre-labeled with fluorescein onto ethylene diamine-plasma-treated carbon nanotubes. The fluorescein labeling allows th e surface immobilization reaction to be followed simply by photoluminescenc e measurements. The resulting polysaccharide-grafted carbon nanotubes are v ery hydrophilic, as demonstrated by X-ray photoelectron spectroscopic and a ir/water contact angle measurements.