Morphology and thermal degradation behavior of highly exfoliated CoAl-layered double hydroxide/polycaprolactone nanocomposites prepared by simple solution intercalation

Abstract

Highly exfoliated CoAl-layered double hydroxide (CoAl-LDH)/polycaprolactone (PCL) nanocomposites were successfully synthesized by simple solution intercalation of PCL into the galleries of organically modified CoAl-LDH (OCoAl-LDH) under reflux in cyclohexanone. The structure and thermal properties of the nanocomposites were characterized by Fourier Transform Infrared spectroscopy (FTIR), X-ray diffraction (XRD), Transmission Electron Microscopy (TEM), Thermal Gravimetry Analysis (TGA) and Differential Scanning Calorimetry (DSC). TGA data show that the thermal degradation temperature of the PCL nanocomposite with the addition of 1 wt% of LDH is lowered by 18 °C as compared to that of neat PCL. Dynamic FTIR spectra, coupled with two-dimensional infrared (2D-IR) correlation spectra, clearly reveal that the decrease in the degradation temperature observed for the nanocomposites is not just due to the decomposition of OCoAl-LDH at low temperature, but also mainly due to the negative catalytic degradation effect of OCoAl-LDH, where the ester groups of PCL matrix are catalytically hydrolyzed by the hydroxyl groups on LDH surface.