Growing Multihydroxyl Hyperbranched Polymers on the Surfaces of Carbon Nanotubes by in Situ Ring-Opening Polymerization

Abstract

An in situ ring-opening polymerization strategy was employed to grow multihydroxyl dendritic macromolecules on the convex surfaces of multiwalled carbon nanotubes (MWNTs), affording novel one-dimensional (1D) molecular nanocomposites. The crude MWNTs were oxidized using 60% HNO3 and then reacted with thionyl chloride, resulting in MWNTs functionalized with chlorocarbonyl groups (MWNT-COCl). MWNT-COCl, when reacted with an excess of glycol, produced hydroxy-functionalized MWNT supported initiators (MWNT-OH). Using the MWNT-OH as the growth supporter and BF3·Et2O as catalyst, multihydroxy hyperbranched polyetherstreelike macromoleculeswere covalently grafted on the sidewalls and ends of MWNTs via in situ ring-opening polymerization of 3-ethyl-3-(hydroxymethyl)oxetane (EHOX). TGA measurements showed that the weight ratio of the as-grown hyperbranched polymers on the MWNT surfaces lay in the 20−87% range. The products were characterized by FTIR, NMR, DSC, TEM, and SEM. TEM indicates that the MWNTs are envelop...