Activating Ru nanoparticles on oxide supports for ring-opening metathesis polymerization

Abstract

Nano-sized particles mounted on heterogeneous oxide supports such as silica have altered reactivity when compared to their homogeneous analogs. In particular, catalyzed olefin metathesis using supported Ru nanoparticles has shown great promise and various methods have been employed to develop functional heterogeneous Ru catalysts. This article reports a method for synthesizing Ru nanoparticles supported on silica and titania. The nanoparticles were characterized using XPS showing Ru(0) dominates when not exposed to air. TEM showed Ru nanoparticle sizes of 3.1 ± 0.8 nm for Ru supported on SiO₂ and 5.6 ± 1.3 nm for Ru supported on TiO₂. The materials demonstrated modest activity in ring-opening metathesis reactions via diazo activation and nanoparticle-embedded polymers of norbornene and norbornadiene were synthesized using dry box and Schlenk line techniques. The Ru/support/polymer composite materials were characterized using proton NMR, XPS, and SEM/EDS.