Ruthenium based catalysts for olefin hydrosilylation: dichloro(p-cymene)ruthenium and related complexes.

We report our third and final investigation into the use of ruthenium based compounds for catalyzing the hydrosilylation of methylvinyldimethoxysilane with methyldimethoxysilane. The catalytic mechanism of dichloro(p-cymene)ruthenium(II) (B1) is examined and compared to that of previously studied, less active catalysts. Density functional theory (DFT) has been applied to explore the possibility of fine-tuning the catalytic ability of B1.

Single-molecule measurement of the strength of a siloxane bond.

Increasing the mechanical stability of artificial polymer materials is an important task in materials science, and for this a profound knowledge of the critical mechanoelastic properties of its constituents is vital. Here, we use AFM-based single-molecule force spectroscopy measurements to characterize the rupture of a single silicon-oxygen bond in the backbone of polydimethylsiloxane as well as the force-extension behavior of this polymer. PDMS is not only a polymer used in a large variety of products but also an important model system for highly flexible polymers.

Modified chemistry of siloxanes under tensile stress: interaction with environment.

We present first principles molecular dynamics simulations of stretched siloxane oligomers in an environment representative of that present in single molecule atomic force microscopy experiments. We determine that the solvent used (hexamethyldisiloxane) does not influence the stretching of the siloxane in the high force regime or the rupture process, but trace amounts of water can induce rupture before the maximum siloxane extension has been attained. This would result in a significantly lower rupture force.