Ibuprofen-loaded poly(ε-caprolactone) layered silicate nanocomposites prepared by hot melt extrusion

Abstract

Ibuprofen loaded poly(epsilon-caprolactone) (PCL) layered silicate nanocomposites were prepared by hot-melt extrusion. The morphology and extent of dispersion of ibuprofen and layered silicate was studied using a combination of wide-angle X-ray diffraction (WAXD), field emission scanning electron microscopy (FESEM) and high resolution transmission electron microscopy (HRTEM). Exhaustive examination across the length scales revealed the composite to have both an intercalated and exfoliated morphology. The ibuprofen was well dispersed and distributed throughout the PCL matrix. Most significantly, the static tensile and dynamic mechanical properties of PCL can be manipulated as a function of nanoclay loading and is dependent on the aspect ratio of clay platelets. The glass transition of PCL increased by up to 16 degrees C on addition of nanoclay, as determined from dynamic mechanical thermal analysis (DMTA). This behaviour was attributed to the constrained mobility of PCL chains intercalated between clay platelets and to the tethering of PCL chains by hydrogen bonding with platelet edges. As a consequence, PCL crystallisation was inhibited and confirmed from non-isothermal crystallisation experiments using differential scanning calorimetry (DSC). The fraction of PCL that was crystalline (X(c)) decreased by 15% on addition of ibuprofen and nanoclay, although the temperature of crystallisation (T(c)) did not change significantly. The dissolution of ibuprofen from PCL can be retarded by addition of layered silicates (nanoclays) to the polymer matrix.