Jw Hans Niemantsverdriet

Chemistry of ethylene glycol on a Rh(100) single-crystal surface

The adsorption and decomposition of ethylene glycol on Rh(100) have been studied with temperature-programmed reaction spectroscopy and reflection absorption infrared spectroscopy. Ethylene glycol adsorbs onto the surface via the hydroxyl groups. At 150 K, both hydroxyl bonds are broken, forming an ethylenedioxy intermediate. At high coverage, a portion of the ethylene glycol molecules dehydrogenate only one hydroxyl bond, forming a monodentate species. These intermediates decompose further, with complete dehydrogenation and simultaneous C--C bond breaking occurring at around 290 K. Hydrogen and carbon monoxide are formed, which desorb at 290 and 500 K, respectively.

Superhydrophobic Polyethylene Films By Catalytic Ethylene Polymerization

Polyethylene films were grown on a flat silica surface modified by the bis(imino)pyridyl iron(II) catalyst during ethylene polymerization in an organic solvent. The resulting films show under certain polymerization conditions superhydrophobic properties. The development of the nascent polymer morphology which leads to the superhydrophobic behavior depends strongly on the polymerization conditions, especially the solvent and the polymerization temperature. Advancing water contact angle as high as 169° and sliding angles as low as 2° for a 10 μl droplet are obtained on these films. SEM images reveal special surface structures of these films containing micrometer-sized islands, submicrometer particles on the islands, and stress nanofibers between the islands, which — in combination — render superhydrophobicity to the polyethylene surfaces.