Thermodynamics of Adsorption on Nanoporous Silicas with Grafted Methylsiloxane and Wettability

• Published in: Protection of metals and physical chemistry of surfaces Vol. 57; no. 1; pp. 22 - 29
• Main Authors: Roshchina, T. M., Shonia, N. K.
• Format: Journal Article
• Language: English
• Published: Moscow Pleiades Publishing 2021; Springer Nature B.V
• Subjects: Adsorption; Aromatic compounds; Characterization and Evaluation of Materials; Chemistry and Materials Science; Contact angle; Corrosion and Coatings; Gas chromatography; Grafting; Heat of adsorption; Hexadecane; Industrial Chemistry/Chemical Engineering; Inorganic Chemistry; Liquid phases; Materials Science; Metallic Materials; Organic compounds; Physicochemical Processes at the Interfaces; Silicon wafers; Tribology; Wettability; Wetting; adsorption; methylsiloxane; hydrocarbons; chemical modification; water; silica
• ISSN: 2070-2051; 2070-206X
• DOI: 10.1134/S2070205121010172

Thermodynamic characteristics of adsorption of different classes of organic compounds on nanoporous silicas with chemically grafted methylsiloxane have been determined by gas chromatography. It was shown that an increase in the concentration of grafted groups from 1.5 to 1.7 nm –2 leads to an increase in the Henry’s constants and heats of adsorption and, as a rule, to a decrease in the standard entropies of adsorption. With respect to arenes, the polarity of the samples is practically the same as that of the liquid phase OV-1. The set of gas chromatographic and static data on vapor adsorption, taking into account the values ​​of the contact angles of wetting with water and hexadecane for similar monolayers fixed on silicon wafers, allows us to conclude that the degree of lyophobization of the surface of the methylsiloxane layers is significantly higher than that of the hexadecyl layers, but inferior to that of the polyfluoroalkyl layers.