Hybrid organic-inorganic polydimethylsiloxane–vanadium–oxo materials crosslinked at the molecular level

Abstract

New hybrid materials made of dimethylsiloxane oligomers (linear and cyclic species) crosslinked at the molecular level by OV(O–)3 units with a very high degree of homogeneity and dispersion, even for a V:Si molar ratio of 10%, have been synthesized and characterized mainly by 29Si and 51V MAS NMR, DSC and DMA. The structure of these hybrids is very different from those proposed for other dimethylsiloxane–transition metal oxide systems. These dimethylsiloxane–vanadate copolymers exhibit higher glass transition temperatures than is usual for PDMS, as well as a very sharp variation of the loss factor tan δ. These hybrid materials exhibit, at low temperature, a strong phosphorescence usually associated with a ligand-to-metal charge transfer process.