A novel use of Ti‐POSS as initiator of L ‐lactide ring‐opening polymerization

The efficacy of a metal‐silsesquioxane, namely, heptaisobutyl (isopropoxyde)titanium‐polyhedral oligomeric silsesquioxanes (Ti‐POSS), as initiator of the ring‐opening polymerization of L‐lactide (LLA) has been assessed. Indeed, as demonstrated by proton nuclear magnetic resonance (1H NMR) spectroscopy and gel permeation chromatography (GPC) measurements, a well‐controlled polymerization occurs via a coordination‐insertion mechanism. Moreover, the above reaction leads to the direct insertion of the silsesquioxane molecule into the polymer backbone, thus producing a hybrid system. Differential scanning calorimetry measurements demonstrated that in comparison with a commercial poly‐L‐lactide (PLLA), the polymers prepared with Ti‐POSS exhibit a higher crystallinity. Indeed, the presence of silsesquioxane molecules, attached to one end of the polymer chains, has been found to appreciably affect the crystal nucleation density.