Upper and lower bounds for interfacial tension using spinning drop devices

Joseph, Daniel D.; Arney, M. S.; Ma, Guoyan

doi:10.1016/0021-9797(92)90140-h

Cited by 10 publications

(9 citation statements)

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“…Surface tension measurements at high dilution (from 0.1 to 5 × 10 –4 g·L –1 ) were carried out on a SVT 20 spinning drop video tensiometer (Dataphysics). The principle of measurement and technical details for this tensiometer are reported in refs and . Measurements were performed in a borosilicated glass capillary with an inner diameter of 2.45 mm, filled with the buffer or A8-35 solutions.…”

Section: Methodsmentioning

confidence: 99%

Well-Defined Critical Association Concentration and Rapid Adsorption at the Air/Water Interface of a Short Amphiphilic Polymer, Amphipol A8-35: A Study by Förster Resonance Energy Transfer and Dynamic Surface Tension Measurements

2012

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Amphipols (APols) are short amphiphilic polymers designed to handle membrane proteins (MPs) in aqueous solutions as an alternative to small surfactants (detergents). APols adsorb onto the transmembrane, hydrophobic surface of MPs, forming small, water-soluble complexes, in which the protein is biochemically stabilized. At variance with MP/detergent complexes, MP/APol ones remain stable even at extreme dilutions. Pure APol solutions self-associate into well-defined micelle-like globules comprising a few APol molecules, a rather unusual behavior for amphiphilic polymers, which typically form ill-defined assemblies. The best characterized APol to date, A8-35, is a random copolymer of acrylic acid, isopropylacrylamide, and octylacrylamide. In the present work, the concentration threshold for self-association of A8-35 in salty buffer (NaCl 100 mM, Tris/HCl 20 mM, pH 8.0) has been studied by Förster resonance energy transfer (FRET) measurements and tensiometry. In a 1:1 mol/mol mixture of APols grafted with either rhodamine or 7-nitro-1,2,3-benzoxadiazole, the FRET signal as a function of A8-35 concentration is essentially zero below a threshold concentration of 0.002 g·L(-1) and increases linearly with concentration above this threshold. This indicates that assembly takes place in a narrow concentration interval around 0.002 g·L(-1). Surface tension measurements decreases regularly with concentration until a threshold of ca. 0.004 g·L(-1), beyond which it reaches a plateau at ca. 30 mN·m(-1). Within experimental uncertainties, the two techniques thus yield a comparable estimate of the critical self-assembly concentration. The kinetics of variation of the surface tension was analyzed by dynamic surface tension measurements in the time window 10 ms-100 s. The rate of surface tension decrease was similar in solutions of A8-35 and of the anionic surfactant sodium dodecylsulfate when both compounds were at a similar molar concentration of n-alkyl moieties. Overall, the solution properties of APol "micelles" (in salty buffer) appear surprisingly similar to those of the micelles formed by small, nonpolymeric surfactants, a feature that was not anticipated owing to the polymeric and polydisperse nature of A8-35. The key to the remarkable stability to dilution of A8-35 globules, likely to include also that of MP/APol complexes, lies accordingly in the low value of the critical self-association concentration as compared to that of small amphiphilic analogues.

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Section: Methodsmentioning

confidence: 99%

Well-Defined Critical Association Concentration and Rapid Adsorption at the Air/Water Interface of a Short Amphiphilic Polymer, Amphipol A8-35: A Study by Förster Resonance Energy Transfer and Dynamic Surface Tension Measurements

2012

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“…The condition J = 4 was derived from heuristic arguments by Vonnegut (1942). It is the working formula for the 'spinning drop' tensiometer which is used to measure interfacial tension (see Joseph, Arney & Ma 1992).…”

Section: Bubbles In a Partially Filled Rotating Cylindermentioning

confidence: 99%

Particle motion in a liquid film rimming the inside of a partially filled rotating cylinder

et al. 2003

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Both lighter- and hydrophobic heavier-than-liquid particles will float on liquid–air surfaces. Capillary forces cause the particles to cluster in typical situations identified here. This kind of clustering causes particles to segregate into islands and bands of high concentrations in thin liquid films rimming the inside of a slowly rotating cylinder partially filled with liquid. A second regime of particle segregation, driven by secondary motions induced by off-centre gas bubbles in a more rapidly rotating cylinder at higher filling levels, is identified. A third regime of segregation of bidisperse suspensions is found in which two layers of heavier-than-liquid particles that stratify when there is no rotation, segregate into alternate bands of particles when there is rotation.

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“…Most of the so-called shape methods rely on gravity to deform a drop in order to measure interfacial tension; long times are required for reaching equilibrium due to high viscosities but these polymeric systems undergo risks of polymer degradation. The spinning drop tensiometer uses centripetal acceleration to control shape; the time to equilibrium can be controlled by over and under spinning [45].…”

Section: The Spinning Drop Tensiometermentioning

confidence: 99%

High temperature interfacial tension measurements of PA6/PP interfaces compatibilized with copolymers using a spinning drop tensiometer

Verdier¹,

Vinagre

Piau³

et al. 2000

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Upper and lower bounds for interfacial tension using spinning drop devices

Cited by 10 publications

References 2 publications

Well-Defined Critical Association Concentration and Rapid Adsorption at the Air/Water Interface of a Short Amphiphilic Polymer, Amphipol A8-35: A Study by Förster Resonance Energy Transfer and Dynamic Surface Tension Measurements

Well-Defined Critical Association Concentration and Rapid Adsorption at the Air/Water Interface of a Short Amphiphilic Polymer, Amphipol A8-35: A Study by Förster Resonance Energy Transfer and Dynamic Surface Tension Measurements

Particle motion in a liquid film rimming the inside of a partially filled rotating cylinder

High temperature interfacial tension measurements of PA6/PP interfaces compatibilized with copolymers using a spinning drop tensiometer

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