Components and parameters of synthetic chalcocite surface tension and its wettability by aqueous solution of n-octyl-β-D-glucopyranoside

The measurements of advancing contact angle of water, glycerol, formamide, ethylene glycol, diiodomethane, α-bromonaphthalene, 1,2,3-tribromopropane and aqueous solution of n-octyl-β-D-glucopyranoside (OGP) on unoxidized and oxidized synthetic chalcocite at the temperatures equal to 293, 303 and 313 K were made. Using the obtained contact angle values of the pure liquids the components and parameters of the unoxidized and oxidized synthetic chalcocite surface tension were calculated. For this calculation, different methods based on the Young equation were applied. It follows that the surface tension of both forms of chalcocite does not practically depend on the temperature in the range from 293 to 313 K. Taking into account the calculated values of components and parameters of unoxidized and oxidized chalcocite surface tension their wettability by the aqueous solution of n-octyl-β-D-glucopyranoside was considered. It appeared that wettability of the unoxidized chalcocite by aqueous solution of OGP can be predicted on the basis of the chalcocite surface tension components and parameters

FTIR ATR study of adsorption of trisiloxanes and hydrocarbon surfactants at hydrophobic solids from aqueous solutions

Kinetics of the integrated absorbance in C−H stretch region for ethoxylated trisiloxane and alkyl polyethoxylate surfactants on low- and highly hydrophobic surfaces has been measured by Fourier-Transform Infrared spectroscopy (FTIR) in the attenuated total reflection (ATR) mode. It has been found that regardless of the surface energy of substrate the absorbance of trisiloxanes continuously increases during the experiment (characteristic time scale is ten minutes), while the absorbance of alkyl polyethoxylate surfactants reaches equilibrium for tens of seconds on low hydrophobic and for a few minutes on the highly hydrophobic surfaces. The continuous growth of absorbance with increasing bulk concentration of surfactants has been detected in the case of trisiloxanes on both substrates even at concentrations above critical wetting concentration; while hydrocarbon surfactants attained the constant values of absorbance at concentrations above critical aggregation concentration. The results for alkyl polyethoxylate surfactants obtained from FTIR-ATR spectra are consistent with the results obtained by other authors used neutron and optical reflectometry. Influence of the length of hydrophilic chains on the value of the absorbance of surfactants has been analyzed. In the case of alkyl polyethoxylate surfactants the absorbance decreases with increasing the length of hydrophilic ethoxy groups. However, in the case of trisiloxane surfactants studied the above trend cannot be clearly traced. Some aspects associated with the relationship between adsorption of trisiloxanes at hydrophobic solid/liquid interfaces and spreading kinetics are discussed