Multivalent-Counterion-Induced Surfactant Multilayer Formation at Hydrophobic and Hydrophilic Solid-Solution...

Area of Science:

• Surface Chemistry
• Materials Science
• Colloid Science

Background:

• Anionic-nonionic surfactant mixtures are crucial in various industrial applications.
• Understanding solid-solution interfaces is key to controlling surface properties.
• Multivalent ions significantly influence surfactant aggregation and adsorption behavior.

Purpose of the Study:

• To investigate surface multilayer formation using a specific surfactant mixture and multivalent ions.
• To characterize the influence of different solid surfaces (silica and cellulose) on multilayer development.
• To explore the relationship between surface multilayers, wetting, and adsorption.

Main Methods:

• Neutron reflectivity (NR) was employed to characterize the surface multilayers.
• Experiments were conducted on both hydrophobic and hydrophilic silica and cellulose surfaces.
• The study utilized a mixture of sodium dodecyl dioxyethylene sulfate (SLES) and monododecyl dodecaethylene glycol (C12E12) with Al(3+) counterions.

Main Results:

• Surface multilayer formation was successfully observed and characterized at the solid-solution interface.
• Multilayer structures were formed on both silica and cellulose surfaces, with varying degrees of development.
• Silica surfaces exhibited more pronounced and well-developed multilayer formation compared to cellulose surfaces.
• Surface inhomogeneities of cellulose were identified as a factor limiting multilayer coherence and growth.

Conclusions:

• The addition of multivalent Al(3+) ions effectively induces surface multilayer formation from SLES/C12E12 surfactant mixtures.
• Surface properties, particularly surface inhomogeneities, dictate the extent of multilayer development.
• These surface multilayers demonstrate extreme wetting properties, offering potential for surface modification and enhanced adsorption control.