Surface modification approach to the patterned assembly of single-walled carbon nanomaterials

A surface modification strategy has been employed for the patterned assembly of single-walled carbon nanomaterials onto oxide surfaces. The method relies on distinct molecular recognition properties of different functional groups toward the carbon graphitic structure. The surface modification starts with reactions between bifunctional molecules 1 (with amino and silane groups) and hydroxyl groups on an oxide substrate, generating an amine-covered surface. This is followed by a coupling step where bifunctional molecules 2 (with succinimidyl ester and pyrene groups) react with amines. With one area covered with pyrenyl groups and the other one covered with hydroxyl groups, the patterned assembly of a single layer of single-walled carbon nanohorns (SWNHs) has been demonstrated. The strategy employed herein is quite generic and applicable to a variety of oxide substrates, including quartz, SiO2 layer on Si, and indium tin oxide (ITO). Because silane chemistry is compatible with soft or lift-off lithography, an extension of this methodology to micrometer-scale patterning has been achieved, and a further reduction of the size feature should be possible. In addition, the patterned assembly of single-walled carbon nanotubes (SWNTs) has also been realized. These surf ace-immobilized structures should open up new possibilities in such areas as nanoelectronics, chemical sensing, field-emission displays, nanotribology, and cell adhesion/biorecognition investigations.