Kinetics of Sodium Dodecyl Sulfate Adsorption on and Desorption from Self-Assembled Monolayers Measured by Surface Plasmon Resonance

Abstract

By use of a flow cell in conjunction with surface plasmon resonance, experimental results are obtained for the intrinsic kinetics of sodium dodecyl sulfate (SDS) adsorption on and desorption from self-assembled monolayers (SAMs) on gold. When the flow of the bulk surfactant solution in the flow cell is increased, conditions are reached where the surface kinetics are rate controlling and mass transfer limitations in the bulk solution are negligible. The SDS adsorption and desorption rates increase with the bulk surfactant concentration in the monomer regime. At and above the critical micelle concentration of SDS, the adsorption and desorption rates become nearly constant. It is shown that SDS needs to be recrystallized to remove minute impurities. The results suggest that the SDS monomers play a dominant role in adsorption and desorption on SAMs. Sodium dodecyl sulfate has a greater affinity for hydrophobic SAMs than for charged, hydrophilic SAMs. The data also suggest that the kinetics of adsorption and surface micelle formation for hemicylinders is a slower process than that for adsorption and formation of hemispheres.

A Simple and Effective Route for the Synthesis of Crystalline Silver Nanorods and Nanowires

“…[23] SDSN has also been explored [24] because it is more difficult to hydrolyze than sodium dodecylsulfate (SDS), which was more commonly studied. [25] It is necessary to point out that SDSN served only as a capping agent in the present study. Its concentration (1 mM) is far lower than the critical concentration for the formation of spherical micelles (9.7 mM, 40 C), especially at the reaction temperature of 100 C, since the concentration of the micelle formation increases for SDSN as temperature rises.…”

Stick–Slip Friction of Stainless Steel in Sodium Dodecyl Sulfate Aqueous Solution in the Boundary Lubrication Regime

“…There have been a lot of investigations on the details of the adsorption process and adsorption structures of surfactants at solid/liquid interfaces [29][30][31][32][33][34][35][36][37][38][39][40]. Adsorption isotherm is the most widely used traditional method to provide evidence for surfactant aggregation, and the structure is interpreted with regard to the measured surface excess or adsorbed mass [32].…”

Correlation Between Adsorption/Desorption of Surfactant and Change in Friction of Stainless Steel in Aqueous Solutions Under Different Electrode Potentials

“…Considerable studies have been done to investigate the details of the adsorption process and aggregate structures of surfactants [6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. Many experimental techniques including quartz crystal microbalance (QCM) [11,13,14], atomic force microscopy (AFM) [6][7][8][9], X-ray photoelectron spectroscopy [11,13], nuclear magnetic resonance [6,7], electrochemistry [8,10,14], and neutron reflectivity [10] have been employed to study surfactant adsorption at solid-liquid interfaces.…”

“…Soares et al characterized the formation of self-organized structures of sodium dodecyl sulfate (SDS) from dilute aqueous solutions (concentration below the critical micelle concentration or CMC) on bare gold surfaces using both QCM and electrochemical techniques, and pointed out that amphiphilic molecules were adsorbed and associated physically, not chemically [14]. Ionic surfactants can adsorb onto oppositely charged gold surfaces to form a boundary film in aqueous solutions [7][8][9][10][15][16][17][18][19]. Burgess et al [8,9] used high-resolution AFM images to demonstrate the effect of the absolute surface charge density on the coverage and aggregate structure of dodecyl sulfate on S. He Á Y. Meng (&) Á Y. Tian State Key Laboratory of Tribology, Tsinghua University, Beijing 100084, China e-mail: mengyg@tsinghua.edu.cn a bare Au (111) electrode under different electrode potentials.…”