Predicting Adsorption on Bare and Modified Silica Surfaces

Abstract

International audienc

Probing the microporosity of low-k organosilica films: MP and t-plot methods applied to ellipsometric porosimetry data

“…The obtained porous low-k samples consisted of a "bulk" SiOCH layer (k~2.55). One sample was further exposed for 30 s at 350 C to standard fluorinated plasma etching process used for line and via patterning [4] in order to modify its surface functionalization [18,19].…”

“…The reference t-curves for these modified materials cannot be determined experimentally because their chemistry and morphology depend to a great extent on porosity. In this work, the pore sizes were estimated using the MP method with (1) the classical Harkins and Jura equation and (2) simulated t-curves obtained by means of molecular modeling [19] (the latter are shown in Fig. 4).…”

“…t-curves for (a) water, (b) methanol, and (c) toluene adsorbed at 300 K on hydroxylated (black), partially methylated (dark red) and fully methylated (light red) silica surfaces. These data were obtained by means of Grand Canonical Monte Carlo simulations [19]. (For interpretation of the references to color in this figure legend, the reader is referred to the web version of this article.…”

“…Molecular simulations (Grand Canonical Monte Carlo) were then used to predict the t-curves of different adsorbates, i.e. water, methanol, and toluene, on silica with different chemically modified surfaces [19].…”

Equation of state for methane in nanoporous material at supercritical temperature over a wide range of pressure

“…Some of the gas storage mechanisms can be revealed by the advanced experimental technologies today, for example, the gas storage properties (adsorbed gas density and layers number) characterized by the Nuclear Magnetic Resonance 14 , even the adsorption sites and the ordering of adsorbed gas molecules detected by in situ small-angle X-ray scattering 49,50 . The gas storage mechanisms are mainly dominated by the ratio of the interaction between gas molecules and nanopores wall to gas intermolecular interaction 8,39,59 . For gas storage in nanopores with walls of homogeneous chemical and physical properties, while the interaction between gas molecules and nanopores wall dominates (F S-F / F F-F Ͼ 1), gas storage amount first increases sharply with pressure in the low pressure region, then slowly in the relatively high pressure region 11,60 , and finally becomes a constant due to the storage saturation limited by the space available for the gas molecules 61 (see Fig.…”