New organic-inorganic nanohybrids via ring opening polymerization of (di)lactones initiated by functionalized polyhedral oligomeric silsequioxane

The synthesis of new organic-inorganic materials were investigated. Poly(e-caprolactone) and poly(l, l-lactide) covalently end-capped by a polyhedral oligomeric silsesquioxane (POSS) moiety, leading to new nanohybrid materials, were successfully prepared by coordination-insertion ring opening polymerization (ROP) of e-caprolactone (e-CL) and l,l-lactide (l,l-LA) respectively. The reaction was initiated from the primary amine available on aminopropylheptakis(isobutyl)POSS nanoparticles and catalyzed by tin(II) 2-ethylhexanoate (tin octoate, Sn(oct)2). The covalent grafting of the polyester chains onto the POSS 'nanocages' was assessed by selective fractionation experiment, Fourier transform infrared spectroscopy (FTIR) and further confirmed by proton nuclear magnetic resonance (1H NMR). The polymerization proved to be well controlled as attested by the quite narrow polydispersity indices as determined by size exclusion chromatography (SEC). Furthermore, well-defined semi-crystalline poly(e-caprolactone)-b-polylactide block copolymer carrying such POSS nanoparticle at one end was successfully synthesized attesting for the very efficient control over the polymerization reaction.