科研之友
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摘要
The efficacy of a metal-silsesquioxane, namely, heptaisobutyl (isopropoxyde)titanium-polyhedral oligomeric silses-quioxanes (Ti-POSS), as initiator of the ring-opening polymerization of L-lactide (LLA) has been assessed. Indeed, as demonstrated by proton nuclear magnetic resonance ((1)H 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.
- 出版日期2011-11-15
