Much effort has been directed to the fabrication of polymer/multiwalled carbon nanotubes (MWCNTs) nanocomposites and the characterization of their physical properties. However, the enhancement of physical properties of nanocomposites has been greatly hampered by the limited available interface area of MWCNTs in nanocomposites. To overcome this intrinsic limitation, we investigated the nanocomposites of poly(L-lactide) (PLLA)/unzipped MWCNTs (mu CNTs), in which the mu CNTs were subjected to oxidative unzipping with different amounts of oxidant (KMnO4). Besides the characterization of the mu CNTs, the crystallization of PLLA, the interface and the possible interaction between PLLA and mu CNTs were well characterized by several measurements including Fourier transform infrared (FT-IR) spectra, dynamic mechanical analysis (DMA) and differential scanning calorimetry (DSC), etc. As found, the interaction between PLLA and mu CNTs can be roughly tuned by controlling the oxidation degree of the MWCNTs. In this case, the ultimate values of the weight loss (a direct measure of the hydrolytic property) after 24 days exposure to NaOH solution can reach around 82.2 wt% for the PLLA/mu CNT-5 nanocomposite, comparing to 41.8 wt% for neat PLLA. Additionally, the incorporation of mu CNTs was found to accelerate the hydrolytic degradation of PLLA in the nanocomposites. (c) 2012 Elsevier B.V. All rights reserved.