Surface characterization of poly(ε-caprolactone)-based nanocomposites

This work deals with the preparation and the surface characterization of biodegradable nanocomposites made of poly(e-caprolactone) (PCL) and a montmorillonite-type clay. Nanocomposites with different relative compositions of PCL and montmorillonite, either natural or organo-modified by various alkylammonium cations, are prepared by melt intercalation and in situ intercalative polymerization. The goal of this study is to characterize the dispersion of the clay layers in PCL, which is a critical parameter governing the final physical properties of the obtained nanocomposites. Morphological studies of PCL nanocomposites are carried out by means of scanning probe microscopy techniques while surface analysis is performed both by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The results demonstrate that the dispersion of the clay layers is strongly dependent on both the synthetic route and the type of alkylammonium chains used for the cationic exchange. Whereas the melt-intercalation method leads to intercalated nanocomposites only after cationic exchange, the in situ polymerization method allows for reaching a much finer dispersion, even for the unmodified natural clay.