Showing papers by "Giorgio Speranza published in 2000"

Surface study of perfluoropolyether–urethane cross‐linked polymers

Abstract: A surface study of two different monocomponent polyurethane coatings containing perfluoropolyether macromers is presented. Different techniques were used in order to investigate the structural characteristics of the two polymers. In particular, transmission infrared spectroscopy provided information about the chemical groups and linkages present in the polymer network, and attenuated total reflectance spectra showed a higher concentration of urea groups close to the surface. X-ray photoelectron spectroscopy analysis at two different sampling depths showed clear evidence of fluorine enrichment and nitrogen depletion in the first nanometres of material with respect to the bulk composition of the two polymers. Analysis of the outermost layer by time-of-flight secondary ion mass spectrometry confirmed the XPS data with a predominant presence of fluorinated fragments. Contact angles of the two coatings with water and paraffins were measured and the critical surface tension of wetting, γc, was estimated (13–16 mN m−1 at 20 °C) and compared with the known data of other fluoropolymers. Copyright © 2000 John Wiley & Sons, Ltd.

Cubic boron nitride deposition on silicon substrates at room temperature by KrF excimer laser ablation of h-BN

Abstract: A hexagonal-BN target was ablated by high-fluence (6 and 12 J/cm2) KrF excimer laser pulses in low-pressure (5 Pa) N2 atmosphere, without any aid of ion bombardment and heating of the Si substrate. Investigations of the deposited films show that the cubic-BN phase was deposited. The film deposited at 6 J/cm2 appears to contain a higher cubic phase content with respect to the one deposited at 12 J/cm2.