Hybrid materials Co-operative Formation of Monolithic Tungsten Oxide– Polybenzylene Hybrids via Polymerization of Benzyl Alcohol and Study of the Catalytic Activity of the Tungsten Oxide Nanoparticles Inga Olliges-Stadler, Marta D. Rossell, and Markus Niederberger* Hard and brittle monolithic tungsten oxide-polybenzylene nanohybrids can be obtained in one step by reacting tungsten iso-propoxide with benzyl alcohol. In a first step, crystalline tungsten oxide W 18 O 49 nanowires with a diameter of about 1.5 nm form via ether elimination reaction. Subsequently, the large residue of the benzyl alcohol is transformed to dibenzyl ether, which then polymerizes to polybenzylene, incorporating the nanoparticles into the forming polymer. The catalytic effect of the tungsten oxide nano- wires on the quantitative formation of polybenzylene is proven by reacting them in different concentrations and at varying temperatures either with benzyl alcohol or with dibenzyl ether. Complete polymerization of benzyl alcohol is achieved within just 30 min by using a particle-to-monomer molar ratio of 1:115 at 160 8C. Lower reaction temperatures (100–130 8C) or higher ratios (1:340 and 1:680) prolong the reaction time to several hours. Further studies show that the tungsten oxide nanoparticles are able to completely polymerize various other alcohols with an aryl methanol group. 1. Introduction Although nanocomposites or hybrid materials have been used for centuries, they did not lose any scientific or technological attractiveness. The fascination of creating either new or combining different properties through merging organic and inorganic components motivated scientists to develop new materials for optics, electronics, coatings, catalysis, and sensors. [1–5] Hybrid materials are commonly distinguished in the two classes, type I and type II. [6] Type-I materials are characterized by weak interactions such as Van der Waals forces, hydrogen bonds, or ionic attractions, whereas type-II materials have strong covalent or iono–covalent interactions between the organic and the inorganic constituents. The available synthesis methodologies are as manifold as the structural variety of the materials itself. In principle, there are three different methods for their preparation. In the simplest case, the organic and inorganic components are mechanically blended. In the second approach, one of the constituents is synthesized from the precursor or monomer in the presence of the other preformed compound, for example, polymerization of an organic matrix around the inorganic nanoparticles, or the synthesis of the inorganic component in the organic matrix. The third way involves the simultaneous formation of both components from precursors. In general, this approach is regarded as producing the most homogeneous composites, but at the same time it also represents the most challenging strategy. The large number of chemical species present in the initial reaction mixture increases the risk of side reactions and the formation of undesired by-products. The development of hybrid materials is closely associated with sol–gel chemistry. [2,6] The sol–gel process offers a versatile full papers [  ] Prof. M. Niederberger, Dr. M. D. Rossell, I. Olliges-Stadler Laboratory for Multifunctional Materials Department of Materials, ETH Zurich Wolfgang-Pauli-Strasse 10, 8093 Zurich (Switzerland) E-mail: markus.niederberger@mat.ethz.ch : Supporting Information is available on the WWW under http:// www.small-journal.com or from the author. DOI: 10.1002/smll.200902289 Keywords:  catalysis  hybrid materials  nanoparticles  polybenzylene  tungsten oxide 960 ß 2010 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim small 2010, 6, No. 8, 960–966