Sequential Adsorption of Triton X-100 and Sodium Dodecyl Sulfate onto Positively and Negatively Charged Polystyrene Latexes

Abstract

Individual and sequential adsorption of the anionic surfactant sodium dodecyl sulfate (SDS) and the nonionic surfactant Triton X-100 on cationic and anionic polystyrene latexes has been examined. Both latex samples, although charged differently (−16.2 and +11.0 µC cm −2 ), must be considered hydrophobic polymer colloids. The adsorbed amounts of both surfactants on cationic and anionic latexes were found to be different as a consequence of the dissimilar interfacial properties of these two surfactants. In addition, a comparison between the two surfactants showed that SDS is more easily replaced than Triton X-100 when sequential adsorption on both latexes was studied. It was found that the electrophoretic mobility of surfactant latex complexes depends on the addition sequence order of both surfactants. In relation to colloidal stability, when a layer of a nonionic surfactant is adsorbed on the surface of latexes, the electrosteric mechanism explains the experimental results. If SDS is adsorbed the stabilization or unstabilization is a consequence of the changes in the electrical repulsion between particles. However, when both surfactants are adsorbed, the assumption of additivity is not correct; that is, the electrostatic repulsion (V R ) and the steric repulsions (V osm and V vr ) are not totally independent. C 2001 Academic Press Key Words: cationic and anionic polymer colloids; nonionic and anionic surfactant adsorption; sequential adsorption; colloidal stability.

Adsorption of different amphiphilic molecules onto polystyrene latices

“…However, a step appeared in the case of the Lx(SO 3 H) that pointed out, once more, that the surfactants can associate on the surface before reaching a final plateau, as has been shown theoretically for this kind of surfactant [36]. The fact that the highest adsorbed amount of Triton X-100 corresponded to the most hydrophobic sur-face was also found by comparing the adsorption of this surfactant on a latex with carboxylic groups and on another one with amidine groups (more hydrophobic) [35]. By using the molecular area of the surfactant at the air/solution interface, we could calculate an approximated adsorbed amount in monolayer of (3.1-3.5) µmol/m 2 .…”

“…There exist recent works about the adsorption of Triton X-100 and Triton X-405 on polystyrene latex particles [19,34,35]. In this work, we compare the effect of the surface hydrophobic/hydrophilic character, working with two latices, Lx(SO 3 H) and Lx(HEMA), as adsorbent surfaces.…”

Electromagnetophoretic Measurements of Adsorption Forces of Polystyrene Microparticles on Silica Surfaces in Surfactant Solutions

“…Because the final concentration of particles was 4:5 Â 10 6 -5:7 Â 10 5 particles mL À1 , the amount of surfactants was enough to cover all polystyrene particle surfaces. [17][18][19] Silica Surface and Its Modification. The adsorption force of polystyrene particles was investigated for a bare fused-silica and a surface-modified fused-silica using squalane.…”

Modeling particle size distribution in emulsion polymerization reactors

“…The adsorption of ionic and non-ionic surfactants on latex particles is frequently well described by a simple Langmuir isotherm [106][107][108]. On the other hand, the adsorption of mixed ionic/non-ionic systems appears to be more complex to describe quantitatively due to the complex mechanisms involved [97,109].…”