Journal of Sol-Gel Science and Technology 33, 39–45, 2005 c  2005 Springer Science + Business Media, Inc. Manufactured in The United States. Inorganic-Organic Hybrid Polymers from the Polymerisation of Methacrylate-Substituted Oxotantalum Clusters with Methylmethacrylate: A Thermomechanical and Spectroscopic Study ANGELIKA BASCH Ian Wark Research Institute, University of South Australia, Mawson Lakes Campus SA 5095, Australia SILVIA GROSS Institute of Molecular Science and Technology-CNR, Department of Chemical Science, University of Padova, Padova, Italy NAMITA ROY CHOUDHURY ∗ AND JANIS MATISONS † Ian Wark Research Institute, University of South Australia, Mawson Lakes Campus SA 5095, Australia Abstract. New inorganic-organic hybrid materials were prepared by free-radical polymerization of methyl methacrylate (MMA) with methacrylate-substituted oxotantalum cluster [Ta 4 O 4 (OEt) 8 (OMc) 4 ] and their prop- erties evaluated. The cluster was prepared by the reaction of the parent alkoxide with methacrylic acid. Samples of the hybrid materials were produced with Ta-cluster to methyl methacrylate in the ratios of 1:50 and 1:100 and were characterized by thermal and spectroscopic techniques. The glass transition temperatures of the hybrid materials are shifted to higher temperatures than pure PMMA as a result of cross-linking of the polymer by the oxotantalum clusters. The increase in T g is also observed from the dynamic mechanical analysis (DMA). Evidence of crosslinking between the Ta-cluster and PMMA is obtained from infrared spectroscopic study. Surface studies performed by X-ray photoelectron spectroscopy (XPS) provide information about the atomic concentrations of the surface and indicate tantalum bonded to oxygen. Keywords: hybrid, oxotantalum cluster, polymer, thermal analysis, cross linking 1. Introduction Organic-inorganic hybrid is the collective term for fam- ily of materials including organic/inorganic, host-guest supramolecular material, self assembled monolayers, layered inorganic/organic compounds, nanocompos- ites which can be formed by hybridization of organic compounds and inorganic materials. As the reactivities of both organic and inorganic precursors are widely dif- ferent, an inherent tendency, therefore, exists for phase separation. Thus the properties of the hybrid materi- ∗ To whom all correspondence should be addressed. † Present address: Flinders University, South Australia. als are controlled not only by the individual compo- nents but also by physicochemical properties at the in- terphases. In order to achieve molecular dispersion, in- teraction between the organic and inorganic needs to be stronger than the association of the inorganic material. If molecular level mixing is achieved, a resultant loss in individual identity of the component phase occurs and new organic functionalities can be introduced. Thus, depending on the level of interaction between these organic-inorganic phases, hybrid materials can be di- vided into 2 classes: (1) Class I hybrids in which weak phase interaction such as van der Waals, hydrogen or electrostatic interaction between the phases (small or- ganic species embedded in an oxide matrix); (2) Class II