title: Facile functionalization of multilayer fullerenes (carbon nano-onions) by nitrene chemistry and "grafting from" strategy.
abstract: Facile functionalization of multilayer fullerenes (carbon nano-onions, CNOs) was carried out by [2+1] cycloaddition of nitrenes. The products were further derivatized by using the "grafting from" strategy of in situ ring-opening polymerization (ROP) and atom transfer radical polymerization (ATRP). Using one-step nitrene chemistry with high-energy reagents, such as azidoethanol and azidoethyl 2-bromo-2-methyl propanoate, in N-methyl-2-pyrrolidone at 160 degrees C for 16 h, hydroxyl and bromide functionalities were introduced onto the surfaces of CNOs. These hydroxyl CNOs (CNO-OH) and bromic CNOs (CNO-Br) were extensively characterized by various techniques such as thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), Raman spectroscopy and X-ray photo electron spectroscopy (XPS). TGA measurements indicated that the surface hydroxyl and bromide group density reached 1.49 and 0.49 mmol g(-1), respectively. The as-functionalized CNOs showed much better solubility in solvents than pristine CNOs. The CNO-OH were also observed to fluoresce at lambda = 453 nm in water. The CNO-OH and CNO-Br can be conveniently utilized as macroinitiators to conduct surface-initiated in-situ polymerizations. Poly(epsilon-caprolactone) (PCL, 45 wt%) and polystyrene (PS, 60 wt%) were then grafted from surfaces of CNOs through the ROP of epsilon-caprolactone with the macroinitiator CNO-OH and the ATRP of styrene with the macroinitiator CNO-Br, respectively. The structures and morphology of the resulting products were characterized by (1)H NMR, scanning electron microscopy (SEM), TEM, and atomic force microscopy (AFM). The polymer functionalized CNOs have good solubility/dispersibility in common organic solvents. The facile and scalable functionalization approaches can pave the way for the comprehensive investigation of chemistry of CNOs and fabrication of novel CNO-based nanomaterials and nanodevices.
authors.affiliation: Department of Polymer Science and Engineering and Key, Laboratory of Macromolecular Synthesis and Functionalization, Ministry of Education, Zhejiang University, 38 Zheda Road, Hangzhou 310027, PR China.
authors.forename: Li
authors.initials: L
authors.lastname: Zhou
authors.forename: Chao
authors.initials: C
authors.lastname: Gao
authors.forename: Dandan
authors.initials: D
authors.lastname: Zhu
authors.forename: Weijian
authors.initials: W
authors.lastname: Xu
authors.forename: Fanqing Frank
authors.initials: FF
authors.lastname: Chen
authors.forename: Amit
authors.initials: A
authors.lastname: Palkar
authors.forename: Luis
authors.initials: L
authors.lastname: Echegoyen
authors.forename: Eric Siu-Wai
authors.initials: ES
authors.lastname: Kong
mesh_terms: D001966:Bromine / Q000737:chemistry; D037741:Fullerenes / Q000737:chemistry*; D006900:Hydroxylation; D007097:Imines / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D046529:Microscopy, Electron, Transmission; D049329:Nanostructures / Q000737:chemistry* / Q000648:ultrastructure; D011108:Polymers / Q000138:chemical synthesis / Q000737:chemistry; D012995:Solubility; D013057:Spectrum Analysis; D013499:Surface Properties
chemical_list: D037741:Fullerenes; D007097:Imines; D011108:Polymers; C017621:phenylnitrene; D001966:Bromine