Interaction Forces on α-Alumina Surfaces with Coadsorbed Anionic Surfactant and Nonionic Polymer

Abstract

Direct measurements of interaction forces between R-alumina surfaces with coadsorbed anionic surfactant (sodium dodecyl sulfate (SDS) or lithium perfluorooctanesulfonate (LiFOS)) and nonionic polymer poly-(vinylpyrrolidone) (PVP) at pH 3.5 are carried out by colloidal probe atomic force microscopy. In aqueous SDS solutions, the strength of interaction forces is found to depend on the initial SDS concentration, whereas in PVP solutions, the electric double layer interaction is completely screened due to the flat conformation of PVP on R-alumina. The interaction forces are dramatically different for the coaddition of SDS and PVP: electrostatic repulsion is observed above the critical aggregation concentration, and virtually no steric hindrance due to adsorbed polymer chains can be detected. These coaddition effects are attributed to the flat conformation of the adsorbed PVP and the formation of SDS-PVP surface complexes as confirmed by surface tensiometry. The LiFOS-PVP system exhibits characteristics similar to those of the SDS-PVP system, except that the repulsion between adsorbed LiFOS layers is remarkably weak at concentrations above its critical micelle concentration. The effects of sequential addition of SDS and PVP are also investigated.

Direct Force Measurements between Adlayers Consisting of Poly(amidoamine) Dendrimers with Primary Amino Groups or Quaternary Ammonium Groups

“…We have proposed in our previous experiments that the charging-up is relevant in the adsorption of conventional ionic surfactants (14,24). In the present study very similar force profiles were also obtained, as shown in Fig.…”

“…A detailed description of the force measurement technique is shown elsewhere (14,24 Prior to force measurements, the colloidal probe attached to the cantilever was immersed in 0.1 mol dm −3 KOH overnight, followed by a thorough deionized water rinse. Glass plates were washed following the same procedure.…”

“…In particular, the interaction forces between a colloidal probe attached to the cantilever and the sample surface can be measured using the colloidal probe technique developed by Ducker et al (1,2). This technique has been utilized to study the adsorption of surfactants (3,4), linear polymers (5-10), or both of them (11)(12)(13)(14). However, few reports have been published for the adlayer-adlayer interaction consisting of dendritic macromolecules until now (15).…”

Interaction forces between poly(amidoamine) (PAMAM) dendrimers adsorbed on gold surfaces

“…By using this analytical method, the interaction forces between a colloidal probe attached to a cantilever and a sample surface can be measured [13,14]. Since the advantage of this method over the use of surface force apparatus (SFA) [15,16] is a fact that a wide range of sample surfaces can be applied as a target material, there are many reports concerning surface forces on silica [11,17,18], alumina [19][20][21], gold [22], polystyrene [23], and titanium oxide [24]. Also in the current study, QCM measurement has been carried out to estimate the adsorbed amount of the dendrimers on gold.…”

Stabilization of Nanoalumina Colloidal Slips

“…There is a long discussion in literature on the combined effect of a dispersant which is anionic, in our case, with a nonionic additive like the ethylene glycol. Depending on the solution conditions either beneficial synergy or antagonism could occur at the solid/liquid interface, which in many cases can prove tunable …”