Hybrid Nanocomposites Based on Metal Oxides and Polysiloxanes with Controlled Morphology
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1007-S12-55
Hybrid Nanocomposites Based on Metal Oxides and Polysiloxanes with Controlled Morphology Sorin Ivanovici, Christoph Rill, Claudia Feldgitscher, and Guido Kickelbick Institute of Materials Chemistry, Vienna University of Technology, Getreidemarkt 9-165, Vienna, A1060, Austria
ABSTRACT Hybrid materials based on polysiloxanes and metal oxides (SiO2, TiO2, ZrO2) were prepared by hydrosilation of allyl acetoacetate (AAA) modified metal alkoxides (M(OR)4; M = Ti, Zr; R = ethyl, isopropyl) or vinyl triethoxysilane with poly(dimethylsiloxane-cohydrosiloxane) (PDMS-co-PMHS). The obtained compounds acted as single-source precursors in the sol-gel process. Various spectroscopic methods showed the complete functionalization of the polysiloxane chains with the complexes. When alcohols were used as solvents in the sol-gel process, hybrid nanoparticles were obtained, as observed by dynamic light scattering (DLS) measurements, transmission electron microscopy (TEM), and spectroscopic methods such as NMR and FT-IR. INTRODUCTION Polysiloxanes are a class of polymers with a broad range of different properties, such as flexibility, low Tg, biocompatibility, high oxygen permeability [1, 2], and thus a variety of applications, which makes them also attractive for the synthesis of hybrid materials. Several studies recently reported the preparation of polysiloxane based hybrid materials [3-7]. In this manner enhanced mechanical properties of the polysiloxanes could be obtained by combination with sol-gel based materials. Structured inorganic-organic composite materials became an important field in materials research due to the improved properties which can arise from the junction of the two components but also from the micro- and nanostructure of the material [8]. The sol-gel process is widely used in the preparation of inorganic-organic hybrid materials due to its mild reaction conditions which leaves many possibilities for the compositional and structural design of the resulting materials [9]. One important challenge for the materials design is the defined and stable linkage between the inorganic and organic components to avoid effects such as micro phase separation. While in the case of the silicon-based sol-gel process the hydrolytically stable Si-C bond can be employed to for such a stable linkage, in the case of transitional metal alkoxides bidentate ligands are used. Their roles are the (i) reduction of the alkoxide reactivity in sol-gel reactions and (ii) the insertion of additional organic functionalities [10]. Following these different pathways for silicon and transition metal alkoxides novel polymer precursors are obtained by functionalization of a polymer backbone with alkoxysilane or transition metal alkoxide groups by strong interactions, e.g. via metal-ligand coordination [11]. Here we report the synthesis of MOx-polysiloxanes (M = Ti, Zr, Si) hybrid nanoparticles and gels based on polysiloxane co copolymers functionalized with modified metal alkoxides. The self-aggregation of the block copolymers in different
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