Functionalization of multi-walled carbon nanotubes via surface unpaired electrons

Abstract

The unpaired electrons on multi-walled carbon nanotubes (MWNTs) treated bynitric–sulfuric mixed acid were detected and characterized by electron spin resonance(ESR). Through reacting with these unpaired electrons, highly soluble acrylamide-graftedMWNTs were successfully prepared and characterized by ESR, FT–IR, UV–vis and atomicforce microscopy (AFM), etc. The results indicate that MWNTs could generatemore unpaired electrons with longer mixed-acid treatment time and could be wellfunctionalized by acrylamide. By AFM analysis, a ‘net’ structure was formedon MWNTs after grafting with acrylamide. This new method has some obviousadvantages of mild reaction conditions and convenient operation, etc. Furthermore,the grafting of MWNTs may have great potential for biomedical applicationsin drug delivery and regenerative medicine owing to their excellent networks.