Inorganic-Organic Hybrid Polymers from Surface-Modified Oxometallate Clusters
- PDF / 1,249,526 Bytes
- 11 Pages / 612 x 792 pts (letter) Page_size
- 12 Downloads / 221 Views
Inorganic-Organic Hybrid Polymers from Surface-Modified Oxometallate Clusters Ulrich Schubert, Gregor Trimmel, Bogdan Moraru, Walter Tesch1,2, Peter Fratzl2, Silvia Gross†, Guido Kickelbick and Nicola Hüsing Institut für Anorganische Chemie, Technische Universität Wien, Getreidemarkt 9, A-1060 Wien, Austria, 1 Ludwig Boltzmann Institut für Osteologie, Hanusch Krankenhaus, Heinrich Collin Str. 30, 1140 Wien, Austria 2 Erich Schmid Institut für Materialwissenschaft der ÖAW & Universität Leoben, Jahnstr. 12, A-8700 Leoben, Austria ABSTRACT Inorganic-organic hybrid polymers were prepared by radical polymerization of methacrylic acid or methyl methacrylate with the (meth)acrylate-substituted oxozirconium and oxotitanium clusters Zr6(OH)4O4(OMc)12 (OMc = methacrylate), Zr4O2(OMc)12, Ti6O4(OEt)8(OMc)8 and Ti4O2(OPri)6(OAcr)6 (OAcr = acrylate). A few mol% of cluster is sufficient for an efficient cross-linking of the polymer chains. Small-angle X-ray scattering data indicate that the cluster size is retained in the polymers and that the microstructure of the cluster cross-linked samples can be described by a dispersion of identical spherical or diskshaped clusters in the polymer. The obtained hybrid polymers exhibit a higher thermal stability because depolymerization reactions are inhibited. Contrary to undoped poly(methyl methacrylate), the cluster cross-linked polymers are insoluble but swell in organic solvents. The solvent uptake upon swelling decreases with an increasing amount of polymerized cluster. INTRODUCTION The so-called POSS-reinforced polymers (POSS = polyhedral oligomeric silsesquioxanes) have gained much interest as a new class of inorganic-organic hybrid material. They are characterized by the covalent incorporation of structurally well-defined organosilicate clusters in organic polymers, and are prepared by copolymerization of organic monomers with mainly the cubic R8Si8O12 clusters, in which one [1] or more [2] of the organic substituents R contains a polymerizable group. In addition to the properties observed for the POSS-systems, the reinforcement of organic polymers by covalently bonded, structurally well-defined oxometallate clusters, especially those of transition metals, could allow interesting modifications of the optical properties of the polymers, and the preparation of polymers with special magnetic or catalytic properties. Only a few oxometallate clusters substituted with polymerizable organic groups and incorporated into organic polymers by covalent bonding were previously known. When Bu12Sn12O14(OH)6(OMc)2 (Bu = butyl, OMc = methacrylate) was copolymerized with methyl methacrylate, only little cross-linking was achieved. The stannate clusters acted mainly as terminating units [3]. Polystyrene foams were produced by copolymerization of styrene with Ti3O2(OPri)5(OCMe=CH2)3(PriOH) [4]. The methacrylate-substituted heteropolyanion †
Present address: Dipartimento di Chimica Inorganica, Metallorganica ed Analitica, Università degli Studi di Padova, via Loredan, I-35131 Padova, Italy CC2.3.1 Downloa
Data Loading...
