Inorganic-organic hybrid materials from poly(methylmethacrylate) crosslinked by an organically modified oxozirconium cluster. Synthesis and characterization

The presence of inorganic moieties in polymers greatly expands the range of their properties and applications and at the same time overcomes some of the disadvantages of conventional polymer chemistry, such as low temperature hardness and brittleness, photochemical instability, or low electric conductivity. In this framework, the cluster Zr4O2(OMe)(12) (OMe = methacrylate) (Zr4), was prepared starting from zirconium butoxide and an excess of methacrylic acid. Inorganic-organic hybrid materials were then synthesized by radical-initiated copolymerization of Zr4 and methylmethacrylate in benzene with different molar ratios. Glassy, highly transparent hybrid polymers were obtained. The thermal behavior, the composition and the structure of the polymers were investigated by elemental analysis, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), infrared spectroscopy (IR), C-13 MAS NMR, X-ray photoelectron spectroscopy (XPS), and inductively coupled plasma atomic emission spectrometry (ICP-AES). The spectroscopic data show that the clusters crosslink the poly(methylmethacrylate) (PMMA) chains and that the oxometallate complexes are completely incorporated into the hybrid materials. Compared with the undoped polymer, the hybrid polymers have enhanced thermal properties and a characteristic dielectric behavior.