Functionalization of Single-Walled Carbon Nanotubes with Well-Defined Polystyrene by 'Click' Coupling

摘要

Covalent functionalization of alkyne-decorated SWNTs with well-defined,azide-terminated polystyrene polymers was accomplished by the Cu(l)-catalyzed[3 + 2]Huisgen cycloaddition.This reaction was found to be extremely efficient in producing organosoluble polymer-nanotube conjugates,even at relatively low reaction temperatures(60 deg C)and short reaction times(24 h).The reaction was found to be most effective when a Cul catalyst was employed in the presence of 1,8-diazabicyclo[5.4.0]undec-7-ene as an additive.IR spectroscopy was utilized to follow the introduction and consumption of alkyne groups on the SWNTs,and Raman spectroscopy evidenced the conversion of a high proportion of sp2 carbons to sp3 hybridization during alkyne introduction.Thermogravimetric analysis indicated that the polymer-functionalized SWNTs consisted of 45% polymer,amounting to approximately one polymer chain for every 200-700 carbons of the nanotubes,depending on polymer moleCular weight.Transmission electron microscopy and atomic force microscopy were utilized to image polymer-functionalized SWNTs,showing relatively uniform polymer coatings present on the surface of individual,debundled nanotubes.