Temperature effect on the adsorption equilibrium at the silica–polyethylene glycol solution interface

• Temperature effect on PEG adsorption equilibrium on silica surface was examined.
• Conformation of polymer chains in solution and on silica surface was determined.
• Structure of polymer layer at silica–PEG solution interface was described.
• Gibbs energy of polymer adsorption on silica surface was calculated.

The influence of temperature in the range 15–35 °C on polyethylene glycol (PEG) adsorption on the silica (SiO2) surface was examined. For this purpose the following methods were applied: spectrophotometry, viscosimetry and potentiometric titrations. They allow determination of polymer adsorbed amounts, its adsorption layer thickness and surface charge density of the solid with the adsorbed PEG. Moreover, viscosity measurements enabled characteristics of macromolecules conformation in the solution, whereas the adsorption experiments – calculation of the Gibbs energy of polymer adsorption. The obtained results indicate that temperature influences the structure of polymer adsorption layer. The temperature rise causes polymer coils developing which results in: the increase of polymer adsorption, its adsorption Gibbs energy, as well as the increase of linear dimensions of PEG chains in the solution and the formation of thicker adsorption layer of the polymer on the solid surface.

The temperature rise causes polyethylene glycol coils developing which results in: the increase of polymer adsorption and its adsorption Gibbs energy, the increase of linear dimensions of PEG chains in the solution, the creation of thicker polymer adsorption layer of greater density on the silica surface.Figure optionsDownload as PowerPoint slide