Double-C-60-end-capped poly(ethylene oxide) (FPEOF) was reinforced with acid-treated multi-walled carbon nanotubes (MWNTs). The storage modulus of FPEOF was significantly enhanced, whereas the crystallization behavior was not significantly affected upon the incorporation of MWNTs. Fourier transform infrared spectroscopy showed the existence of hydrogen-bonding interactions between the ether oxygen atoms on FPEOF and proton-donating functionalities on the MWNTs, leading to a strong matrix-filler interfacial adhesion. The low-temperature storage modulus of a FPEOF/MWNT composite (6.0 GPa) is more than twice that of a poly(ethylene oxide)/fluorinated single-walled carbon nanotube composite (2.5 GPa) with the same nanotube loading of 4 wt%. The thermal stability of FPEOF is also improved by the addition of MWNTs. (C) 2003 Elsevier B.V. All rights reserved.