The dynamic surface tension of SDS— dodecanol mixtures

Fang, Jiping; Joos, P.

doi:10.1016/0166-6622(92)80266-5

Cited by 48 publications

(26 citation statements)

References 12 publications

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“…SDS is known to change the surface tension over time, so we were careful to make new SDS, weekly, for all our samples. 31,32 Additionally, we imaged samples within 8 h of emulsification. We found that bipolar and monopolar droplets are most common at the lowest two concentrations (Figure 2b,c).…”

Section: ■ Results and Discussionmentioning

confidence: 99%

“…To minimize the effect of any dodecanol impurity introduced by the SDS, we made a fresh SDS solution each week. 31,32 The oldest our SDS could have been was 4 days, from Monday to Friday.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

“…We found that the degree of agitation had little effect on the polydispersity of the emulsion sample in our hands. To minimize the effect of any dodecanol impurity introduced by the SDS, we made a fresh SDS solution each week. , The oldest our SDS could have been was 4 days, from Monday to Friday.…”

Section: Experimental Sectionmentioning

confidence: 99%

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Direct Observation of Liquid Crystal Droplet Configurational Transitions using Optical Tweezers

et al. 2020

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Liquid crystals (LCs) are easily influenced by external interactions, particularly at interfaces. When rod-like LC molecules are confined to spherical droplets, they experience a competition between interfacial tension and elastic deformations. The configuration of LCs inside a droplet can be controlled using surfactants that influence the interfacial orientation of the LC molecules in the oil-phase of an oil in water emulsion. Here, we used the surfactant sodium dodecyl sulfate (SDS) to manipulate the orientation of 5CB molecules in a polydisperse emulsion and examined the configuration of the droplets as a function of SDS concentration. We triggered pronounced morphological transitions by altering the SDS concentration while observing an individual LC droplet held in place using an optical tweezer. We compared the experimental configuration changes to predictions from simulations. We observed a hysteresis in the SDS concentration that induced the morphological transition from radial to bipolar and back as well as a fluctuations in the configuration during the transition.

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Section: ■ Results and Discussionmentioning

confidence: 99%

“…To minimize the effect of any dodecanol impurity introduced by the SDS, we made a fresh SDS solution each week. 31,32 The oldest our SDS could have been was 4 days, from Monday to Friday.…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

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Direct Observation of Liquid Crystal Droplet Configurational Transitions using Optical Tweezers

et al. 2020

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“…As illustrated in the introduction, for decades, Eq. 12has been used by many researchers [10,[14][15][16][17]19,20,22,23,25,[27][28][29][30][31][32]34,35,37,38,40] as an easy method for determining a diffusioncontrolled adsorption process and for estimating surfactant diffusivity. A linear dependence between c(t) and t 1/2 is commonly used to determine whether an adsorption process is diffusion-controlled [8], and the surfactant diffusivity is estimated by simply linearly fitting the initial slope of the c(t) curve in the c(t)Àt 1/2 plot by setting this slope equal to 2RTC 0 ffiffiffiffiffiffiffiffiffi ffi D=p p :…”

Section: Short-time Linear Approximation Methodsmentioning

confidence: 99%

“…Due to its simplicity, this short-time linear approximation equation has been widely used to date . Specifically, many researchers [10,[14][15][16][17]19,20,22,23,25,[27][28][29][30][31][32]34,35,37,38,40] have utilized the equation to evaluate surfactant diffusivities or determine the adsorption mechanism of various systems, linearly fitting dynamic surface tension data with the short-time linear approximation equation (c vs. t 1/2 ) for specific ranges of ''short'' time intervals (generally t 1/2 = 0-5s 1/2 , but up to t 1/2 = 200s 1/2 in [22]). A detailed literature review of these diffusivities, estimated by using the short-time approximation method, is reported in Table 1.…”

Section: Introductionmentioning

confidence: 99%

A study on the method of short-time approximation – Criteria for applicability

Casandra

Ismadji

Noskov

et al. 2015

International Journal of Heat and Mass Transfer

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Despite its widespread use in the determination of adsorption mechanisms and the estimation of surfactant diffusivity, the short-time approximation method, used for linearly fitting experimental dynamic surface tension data, should be validly applied only over a very specific range of time intervals or surface pressures. Therefore, the definition of general criteria for the applicability of this method and for error evaluation in diffusivity estimations is fundamental. In this work, a theoretical numerical simulation of the short-time approximation method was conducted, and general benchmarks for its accurate utilization were investigated. Specifically, for systems assuming planar gas-liquid surfaces, diffusion-controlled kinetics and a Langmuir adsorption isotherm, simple rules were developed in terms of limiting surface pressure (p max) and dimensionless time (t ⁄ max) as a function of dimensionless surfactant concentration (C 0 /a). For values greater than the limiting (maximal) conditions, the dynamic surface tension curve deviates from the short-time approximation straight line, and thus, the corresponding linear fitting could lead to significant errors in evaluating the diffusivity. The simple criteria proposed in this study thus precisely define the range of applicability for the short-time approximation method.

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