Controlled release mechanisms of sodium benzoate from a biodegradable polymer and halloysite nanotube composite

Multiscale polymeric composites combining a biodegradable matrix with low cost and biocompatible hybrid nanocarriers promise to supply a new generation of multipurpose devices for drug delivery. The aim of this work was to investigate the release mechanisms of sodium benzoate (NaBz) from halloysite nanotubes (HNTs) embedded in a biodegradable polymer matrix (poly(?-caprolactone)). To that purpose, different amounts of NaBz molecules were successfully incorporated into HNTs using a simple environmentally friendly procedure. The resulting HNT-NaBz nano-hybrids were then incorporated into a poly(?-caprolactone) matrix by high energy ball milling at ambient temperature and in dry conditions. Analysis of the resulting composites showed important effects of the HNT-NaBz nano-hybrids on the thermal and mechanical properties. Controlled drug release, followed by UV spectrophotometry, was also found to be dependent on the HNT-NaBz relative fractions. Experimental data were thus analyzed using a modified Gallagher-Corrigan model and correlated with the nano-hybrid morphologies.