An amphiphilic graft copolymer, hydroxypropylcellulose-graft-poly(E-caprolactone) (HPC-g-PCL), was synthesized by bulk polymerization without a catalyst and characterized with one-dimensional and two-dimensional NMR spectroscopy. Molar substitution of e-caprolactone on HPC (MSCL) was estimated by both gravimetry and H-1-NMR, and the gravimetric method was considered suitable for MSCL determination. Heterogeneity in the HPC-g-PCL film was suggested by a microscopic study, and the existence of PCL-rich crystalline regions was confirmed by the results of X-ray diffraction and differential scanning calorimetry (DSC). The double endotherm observed in the DSC scans of HPC-g-PCL was associated with the different molecular weight fractions in the copolymer. (C) 2003 Wiley Periodicals, Inc.