Bulk and interfacial viscoelasticity in concentrated emulsions: The role of the surfactant

Wulff-Pérez, Miguel; Torcello‐Gómez, Amelia; Martín-Rodríguez, Agustín; Gálvez-Ruiz, Marı́a José; Vicente, J. De

doi:10.1016/j.foodhyd.2010.08.012

Cited by 27 publications

(10 citation statements)

References 29 publications

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“…The interfacial tension isotherms of these surfactants prove that the bulk concentrations used for Pluronic (12 mM) and Epikuron (1 mM) in previous section provided a saturated interface, mimicking the interfacial packing of emulsifier in emulsion lipid droplets in order to correlate with the results obtained by Jódar-Reyes and coworkers in olive O/W emulsions (Jódar-Reyes et al, 2010). Slight differences with the interfacial tension reported by Wulff-Pérez et al (2011) are due to different oil purification methods used. Figs.…”

Section: Adsorption Of Systems Alone At the Bare Oil-water Interfacesupporting

confidence: 69%

“…5 and 6 also display the dilatational modulus E* of the adsorbed layers of Pluronic and Epikuron, respectively. The oscillating frequency was fast enough to assure that the viscous component of the dilatational modulus was negligible (keeping constant with surface concentration) (results not shown) and the adsorbed layers appear predominantly elastic (Wulff-Pérez et al, 2011). The interfacial layer formed by Pluronic F68 (Fig.…”

Section: Adsorption Of Systems Alone At the Bare Oil-water Interfacementioning

confidence: 96%

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Effect of emulsifier type against the action of bile salts at oil–water interfaces

Torcello‐Gómez

Jódar-Reyes

Maldonado-Valderrama

et al. 2012

Food Research International

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Section: Adsorption Of Systems Alone At the Bare Oil-water Interfacesupporting

confidence: 69%

Section: Adsorption Of Systems Alone At the Bare Oil-water Interfacementioning

confidence: 96%

Effect of emulsifier type against the action of bile salts at oil–water interfaces

Torcello‐Gómez

Jódar-Reyes

Maldonado-Valderrama

et al. 2012

Food Research International

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“…Shear and dilatational interfacial rheology experiments at the hexane-water interface were carried out in order to investigate the viscoelastic properties of Pluronic copolymers. As shown in the following, dilatational interfacial rheology experiments were a very sensitive tool for our analysis; whereas, shear interfacial rheology measurements (by a biconical disk interfacial shear rheometer (Anton Paar, Germany)) were very close to the detection limit of the apparatus and could not be used in our analysis [44,45].…”

Section: 1interfacial Rheologymentioning

confidence: 99%

Interfacial rheology and conformations of triblock copolymers adsorbed onto the water–oil interface

Ramírez

Stocco

Muñoz

et al. 2012

Journal of Colloid and Interface Science

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The conformation and the dilatational properties of three non-ionic triblock PEO-PPO-PEO (where PEO is polyethyleneoxide and PPO is polypropyleneoxide) copolymers of different hydrophobicity and molecular weight were investigated at the water-hexane interface. The interfacial behavior of the copolymers was studied by combining dilatational rheology using the oscillating drop method and ellipsometry. From the dilatational rheology measurements the limiting elasticity values, E(0), of the Pluronics as function of surface pressure, Π, and adsorption time were obtained, i.e. E(0)(t) and E(0)(Π). Here, it is shown that E(0)(t) depends on the number of PEO units and on the bulk concentration, showing maximum and minimum surface elasticity values which indicate conformational changes in the interfacial layer. Furthermore, in the framework of the polymer scaling law theory, conformational transitions were discussed in E(0) vs. Π plots. In a dilute regime (Π<14 mN m(-1)) at the water-hexane interface, E(0)=2Π fits well all the data, which indicates a two-dimensional "stretched chain" conformation. Increasing Π, two other interfacial transitions could take place. The different behavior of Pluronic copolymers could be also described by the local minima of E(0), which depends on the hydrophobicity of the copolymers. Conformational transitions observed by interfacial rheology were compared to ellipsometric data. Experimental results were discussed and explained on the basis of two- and three-dimensional copolymer structure taking into account that PPO chains could be partially immersed in hexane and water.

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“…However, when large molecules or small particles are adsorbed at the interface, they do not have the same tendency to desorb from the interface due to the high adsorption energy/particle, 6 and the drop shape will in this case reflect the rheological properties of the air−water interface. 33,35,36 The complex viscoelastic modulus determined with this procedure can be described according to the equation…”

Section: ■ Introductionmentioning

confidence: 99%

Mechanisms Behind the Stabilizing Action of Cellulose Nanofibrils in Wet-Stable Cellulose Foams

Cervin

Johansson²,

Benjamins³

et al. 2015

Biomacromolecules

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The principal purpose of the investigation was to clarify the mechanisms behind the stabilizing action of cellulose nanofibrils (CNFs) in wet-stable cellulose foams. Following the basic theories for particle-stabilized foams, the investigation was focused on how the surface energy of the stabilizing CNF particles, their aspect ratio and charge density, and the concentration of CNF particles at the air-water interface affect the foam stability and the mechanical properties of a particle-stabilized air-liquid interface. The foam stability was evaluated from how the foam height changed over time, and the mechanical properties of the interface were evaluated as the complex viscoelastic modulus of the interface using the pendant drop method. The most important results and conclusions are that CNFs can be used as stabilizing particles for aqueous foams already at a concentration as low as 5 g/L. The major reasons for this were the small dimensions of the CNF and their high aspect ratio, which is important for gel-formation and the complex viscoelastic modulus of the particle-filled air-water interface. The influence of the aspect ratio was also demonstrated by a much higher foam stability of foams stabilized with CNFs than of foams stabilized by cellulose nanocrystals (CNC) with the same chemical composition. The charge density of the CNFs affects the level of liberation within larger aggregates and hence also the number of contact points at the interface and the gel formation and complex viscoelastic modulus of the air-water interface. The charges also result in a disjoining pressure related to the long-range repulsive electrostatic pressure between particle-stabilized bubbles and hence contribute to foam stability.

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Bulk and interfacial viscoelasticity in concentrated emulsions: The role of the surfactant

Cited by 27 publications

References 29 publications

Effect of emulsifier type against the action of bile salts at oil–water interfaces

Effect of emulsifier type against the action of bile salts at oil–water interfaces

Interfacial rheology and conformations of triblock copolymers adsorbed onto the water–oil interface

Mechanisms Behind the Stabilizing Action of Cellulose Nanofibrils in Wet-Stable Cellulose Foams

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