Linear and Hyperbranched Glycopolymer-Functionalized Carbon Nanotubes: Synthesis, Kinetics, and Characterization
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- 作者：Chao Gao ; Sharmila Muthukrishnan ; Wenwen Li ; Jiayin Yuan ; Youyong Xu ; Axel H. E. Mü ; ller
- 刊名：Macromolecules
- 出版年：2007
- 出版时间：March 20, 2007
- 年：2007
- 卷：40
- 期：6
- 页码：1803 - 1815
- 全文大小：1549K
- 年卷期：v.40,no.6(March 20, 2007)
- ISSN：1520-5835
文摘
Linear and hyperbranched glycopolymers, a kind of sugar-containing polymers, were grownsuccessfully from surfaces of multiwalled carbon nanotubes (MWNTs) by the "grafting from" strategy with goodcontrollability and high reproducibility. Linear glycopolymer was grafted from the surfaces of MWNTs by surface-initiated atom transfer radical polymerization (ATRP) of 3-O-methacryloyl-1,2:5,6-di-O-isopropylidene-D-glucofuranose (MAIG) with CuIBr/HMTETA (1,1,4,7,10,10-hexamethyltriethylenetetramine) at 60 
C in ethylacetate. After hydrolysis of polyMAIG in 80 wt % formic acid for 48 h, water-soluble poly(3-O-methacryloyl-
,
-D-glucopyranose) (polyMAG)-grafted MWNTs were obtained. The kinetics were investigated by carryingout the polymerizations using 2-bromo-2-methylpropionyl-immobilized MWNTs (MWNT-Br) as the macroinitiatorin the absence or presence of ethyl 2-bromoisobutyrate as sacrificial initiator. In both cases a linear dependenceof molecular weight on conversion was obtained, and the polymer amounts grafted on MWNTs could be wellcontrolled in a wide range by the reaction time and monomer conversion. Coupling was found in the GPC curvesof free polymer when the conversion of monomer reached ca. 45-50%. This clearly indicates that couplingreactions are more predominant than the conventional ATRP in a homogeneous solution without CNTs, whereno coupling occurred despite of very high conversion of this monomer (>80%). Hyperbranched glycopolymers(HPGs) were also grafted from the surfaces of MWNTs by self-condensing vinyl copolymerization (SCVCP) ofthe monomer, MAIG, and inimer, 2-(2-bromoisobutyryloxy)ethyl methacrylate (BIEMA, AB*) via ATRP withbis(triphenylphosphine)nickel(II) bromide ((PPh3)2NiBr2) at 100 C in ethyl acetate. After deprotection in formicacid, hyperbranched glycopolymers with high density of hydroxyl groups functionalized MWNTs were achieved.The novel water-soluble biocompatible glycopolymer-grafted CNTs have fascinating potentials in the fields oftissue engineering and bionanomaterials.
C in ethylacetate. After hydrolysis of polyMAIG in 80 wt % formic acid for 48 h, water-soluble poly(3-O-methacryloyl-,-D-glucopyranose) (polyMAG)-grafted MWNTs were obtained. The kinetics were investigated by carryingout the polymerizations using 2-bromo-2-methylpropionyl-immobilized MWNTs (MWNT-Br) as the macroinitiatorin the absence or presence of ethyl 2-bromoisobutyrate as sacrificial initiator. In both cases a linear dependenceof molecular weight on conversion was obtained, and the polymer amounts grafted on MWNTs could be wellcontrolled in a wide range by the reaction time and monomer conversion. Coupling was found in the GPC curvesof free polymer when the conversion of monomer reached ca. 45-50%. This clearly indicates that couplingreactions are more predominant than the conventional ATRP in a homogeneous solution without CNTs, whereno coupling occurred despite of very high conversion of this monomer (>80%). Hyperbranched glycopolymers(HPGs) were also grafted from the surfaces of MWNTs by self-condensing vinyl copolymerization (SCVCP) ofthe monomer, MAIG, and inimer, 2-(2-bromoisobutyryloxy)ethyl methacrylate (BIEMA, AB*) via ATRP withbis(triphenylphosphine)nickel(II) bromide ((PPh3)2NiBr2) at 100 C in ethyl acetate. After deprotection in formicacid, hyperbranched glycopolymers with high density of hydroxyl groups functionalized MWNTs were achieved.The novel water-soluble biocompatible glycopolymer-grafted CNTs have fascinating potentials in the fields oftissue engineering and bionanomaterials.