Measurements of Submicron Particle Adsorption and Particle Film Elasticity at Oil–Water Interfaces

• DOI: 10.1021/acs.langmuir.5b04586
• Publication Date: 2016-04-01T21:26:49Z
• Authors: Mohamed S. Manga; Timothy N. Hunter; Olivier J. Cayre; David W. York; Matthew D. Reichert; Shelly L. Anna; Lynn M. Walker; Richard A. Williams; Simon R. Biggs
• Keywords: Particle (ecology); Elasticity

The influence of particle adsorption on liquid/liquid interfacial tension is not well understood, and much previous research has suggested conflicting behaviors. In this paper we investigate the surface activity kinetics charge stabilized pH-responsive polymer colloids at oil/water interfaces using two tensiometry techniques: (i) pendant drop (ii) microtensiometer. We found, both techniques, that particles had little or no (dynamic) tension, although dense silica affected "apparent" measured in pendent drop, due to gravity driven elongation droplet profile. Nevertheless, apparent change additionally allowed study kinetics, which was related qualitatively between systems by estimated diffusion coefficients. Significant real responses were ∼53 nm core–shell latex with a stabilizer poly(methyl methacrylate)-b-poly(2-(dimethylamino)ethyl methacrylate) (pMMA-b-pDMAEMA) diblock copolymer. At pH 2, where strongly charged, behavior similar bare charge-stabilized particles, showing tension. 10, discharged poorly soluble water, significant decrease commensurate strong oil–water interface seen, magnitude free polymer. These results confirmed through profile microtensiometry experiments. Dilational elasticity measurements also performed oscillation droplet; again, changes only seen responsive 10. Frequency sweeps ascertain dilational modulus, values being significantly higher than previously reported for nanoparticle surfactant systems, protein droplets.