Surface Modification of Multiwalled Carbon Nanotubes with Biocompatible Polymers via Ring Opening and Living Anionic Surface Initiated Polymerization. Kinetics and Crystallization Behavior

Multiwalled carbon nanotubes (MWNTs) were functionalized with 2-hydroxyethyl benzocyclobutene (BCB-EO) through a Diels-Alder cycloaddition reaction. The functionalized MWNTs were utilized for the surface initiated ring opening (ROP) catalyzed and anionic polymerization of epsilon-caprolactone (epsilon-CL) and ethylene oxide (EO), respectively. The kinetics of the ROP of epsilon-CL was monitored through thermogravimetric analysis (TGA) which revealed that the polymerization proceeds very fast as compared to that of EO and that both polymerizations could be controlled with time. H-1 NMR, Raman and FTIR spectroscopy, TGA, DSC, and transmission electron microscopy (TEM) were employed for the characterization of these polymer/CNT hybrids. DSC results showed that a remarkable nucleation effect is produced by MWNTs that reduced the supercooling needed for crystallization of both P epsilon CL and PEO. Furthermore, the isothermal crystallization kinetics of the grafted P epsilon CL and PEO was substantially accelerated compared to the neat polymers. The strong impact on the nucleation and crystallization kinetics is attributed to the covalent MWNT-polymer bonding. (C) 2009 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 47: 4379-4390, 2009