Cluster-Crosslinked Inorganic-Organic Hybrid Polymers: Influence of the Cluster Type on the Materials Properties

Methacrylate-substituted tetranuclear tantalum, zirconium and titanium oxide clusters (Zr4O2(OMC)12, Ti4O2(OPr)6(OMC)6, and Ta4O4(OEt)8(OMC)4) were prepared by reaction of the alkoxides with methacrylic acid. The clusters were then polymerized with methyl methacrylate as co-monomers in different molar ratios (0.5-2 mol% of the functionalized cluster). In the resulting inorganic-organic hybrid polymers, the clusters crosslink the polymer chains very efficiently. The physical properties and structural features of the hybrid polymers, investigated by their swelling behavior, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), 13C MAS NMR and impedance spectroscopy, exhibit a clear dependence on the cluster portion in the polymer and on the cluster type.