Unzipped multiwalled carbon nanotubes-incorporated poly(l-lactide) nanocomposites with enhanced interface and hydrolytic degradation

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 (μCNTs), in which the μCNTs were subjected to oxidative unzipping with different amounts of oxidant (KMnO4). Besides the characterization of the μCNTs, the crystallization of PLLA, the interface and the possible interaction between PLLA and μCNTs 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 μCNTs 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/μCNT-5 nanocomposite, comparing to 41.8 wt% for neat PLLA. Additionally, the incorporation of μCNTs was found to accelerate the hydrolytic degradation of PLLA in the nanocomposites.

► Controlled oxidation was used to obtain the CNTs with difference in functionality.
► The interfaces between the PLLA and oxidative CNTs were improved.
► The hydrolytic degradation of PLLA in the nanocomposites was accelerated.