Pattern Formation upon Evaporation of Sessile Droplets of Polyelectrolyte/Surfactant Mixtures on Silicon Wafers

The formation of coffee-ring deposits upon evaporation of sessile droplets containing mixtures of poly(diallyldimethylammonium chloride) (PDADMAC) and two different anionic surfactants were studied. This process is driven by the Marangoni stresses resulting from the formation of surface-active polyelectrolyte–surfactant complexes in solution and the salt arising from the release of counterions. The morphologies of the deposits appear to be dependent on the surfactant concentration, independent of their chemical nature, and consist of a peripheral coffee ring composed of PDADMAC and PDADMAC–surfactant complexes, and a secondary region of dendrite-like structures of pure NaCl at the interior of the residue formed at the end of the evaporation. This is compatible with a hydrodynamic flow associated with the Marangoni stress from the apex of the drop to the three-phase contact line for those cases in which the concentration of the complexes dominates the surface tension, whereas it is reversed when most of the PDADMAC and the complexes have been deposited at the rim and the bulk contains mainly salt.

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The Modeling of Interfacial Contacts in Composites Using the Sitting Drop - Solid Body System as an Example

Key Engineering Materials ◽

10.4028/www.scientific.net/kem.869.400 ◽

2020 ◽

Vol 869 ◽

pp. 400-407

Author(s):

Аleksey A. Ignatiev ◽

Valeriy M. Gotovtsev ◽

Denis V. Gerasimov ◽

Pavel B. Razgovorov

Keyword(s):

Surface Tension ◽

Interfacial Tension ◽

Solid Surface ◽

Interface Layer ◽

Body System ◽

Pressure Tensor ◽

Phase Contact ◽

Interfacial Tensions ◽

Three Phase ◽

The Subject

The paper presents an analysis of positions, which a theory of a liquid wetting a solid surface is based on, using the sitting drop equilibrium as an example. Certain inconsistencies are indicated in these positions, which is the subject of the discussion. The paper explains why the interfacial tension of solid-gas has no effect on the equilibrium of a drop. It proposes a mechanism to form a liquid-solid interface layer, the tensor of interfacial tensions of which is represented as a pressure tensor. It is established that the surface tension of the interface layer is variable and changes in magnitude and direction depending on the wetting conditions. It is determined that it is not possible to present a range of phenomena accompanying the wetting of a solid surface with a liquid by examining the equilibrium of a three-phase contact line.

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Application Performances of Gemini Surfactant as Silk Degumming Auxiliaries

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.233-235.147 ◽

2011 ◽

Vol 233-235 ◽

pp. 147-150

Author(s):

Xiang Rong Wang ◽

Peng Kun Fan ◽

Yun Zhang

Keyword(s):

Surface Tension ◽

Surfactant Concentration ◽

Gemini Surfactant ◽

Surface Active Agent ◽

Active Agent ◽

Silk Fabric ◽

Surface Activities ◽

Anionic Gemini Surfactant ◽

Surface Active ◽

Better Than

To investigate the Application Performances of the anionic gemini surfactant Ethanediyl-α,ω-bis(sodium N-lauroyl-β-alaninate)(EBLA) as silk degumming auxiliaries, the surface activity of the gemini surfactant was measured by the surface tension method. The dependence of degumming rate on surfactant concentration and degumming time were discussed, and the whiteness, tensile strength and capillary effect of the degummed silk fabric were measured. The results revealed that the gemini surfactant possessed excellent surface activities and its degumming effect was pretty good, the critical micelle concentration(CMC) of EBLA was 4.74×10-5 mol·dm-3, and the surface tension at the CMC(γCMC) of it was 26.6 mN·m-1. With lower dosage of the surface active agent and shorter degumming time, the perform indexes of the fabric degummed by the gemini surfactant EBLA were better than those of the fabric degummed by marseille soap.

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The interaction of a moving fluid/fluid interface with a flat plate

Journal of Fluid Mechanics ◽

10.1017/s002211209500214x ◽

1995 ◽

Vol 296 ◽

pp. 325-351 ◽

Cited By ~ 13

Author(s):

J. Billingham ◽

A. C. King

Keyword(s):

Surface Tension ◽

Contact Angle ◽

Flat Plate ◽

Contact Line ◽

Large Time ◽

Dynamic Contact Angle ◽

Dynamic Contact ◽

Phase Contact ◽

Three Phase ◽

Time Problem

A well-known technique for metering a multiphase flow is to use small probes that utilize some measurement principle to detect the presence of different phases surrounding their tips. In almost all cases of relevance to the oil industry, the flow around such local probes is inviscid and driven by surface tension, with negligible gravitational effects. In order to study the features of the flow around a local probe when it meets a droplet, we analyse a model problem: the interaction of an infinite, initially straight, interface between two inviscid fluids, advected in an initially uniform flow towards a semi-infinite thin flat plate oriented at 90° to the interface. This has enabled us to gain some insight into the factors that control the motion of a contact line over a solid surface, for a range of physical parameter values.The potential flows in the two fluids are coupled nonlinearly at the interface, where surface tension is balanced by a pressure difference. In addition, a dynamic contact angle boundary condition is imposed at the three-phase contact line, which moves along the plate. In order to determine how the interface deforms in such a flow, we consider the small- and large-time asymptotic limits of the solution. The small-time and linearized large-time problems are solved analytically, using Mellin transforms, whilst the general large-time problem is solved numerically, using a boundary integral method.The form of the dynamic contact angle as a function of contact line velocity is the most important factor in determining how an interface deforms as it meets and moves over the plate. Depending on this, the three-phase contact line may, at one extreme, hang up on the leading edge of the plate or, at the other extreme, move rapidly along the surface of the plate. At large times, the solution asymptotes to an interface configuration where the contact line moves at the far-field velocity.

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The influence of mixed cationic–anionic surfactants on the three-phase contact parameters in silica–solution systems

Colloids and Surfaces A Physicochemical and Engineering Aspects ◽

10.1016/j.colsurfa.2010.10.040 ◽

2011 ◽

Vol 373 (1-3) ◽

pp. 145-151 ◽

Cited By ~ 14

Author(s):

L. Alexandrova ◽

K. Hanumantha Rao ◽

K.S.E. Forsberg ◽

L. Grigorov ◽

R.J. Pugh

Keyword(s):

Anionic Surfactants ◽

Phase Contact ◽

Silica Solution ◽

Three Phase ◽

Contact Parameters

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Patterns from Drops Drying on Inclined Substrates

Soft Matter ◽

10.1039/d1sm00714a ◽

2021 ◽

Author(s):

P. Logesh Kumar ◽

Sumesh P Thampi ◽

Madivala G Basavaraj

Keyword(s):

Contact Line ◽

Phase Contact ◽

Coffee Ring ◽

Three Phase ◽

Coffee Ring Effect ◽

Evaporative Flux ◽

Ring Effect

Coffee ring effect results from the migration of particles in a drying particle laden drop and their subsequent deposition at the three phase contact line. The evaporative flux during the...

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Ethyl Lauroyl Arginate, an Inherently Multicomponent Surfactant System

Molecules ◽

10.3390/molecules26195894 ◽

2021 ◽

Vol 26 (19) ◽

pp. 5894

Author(s):

Agnieszka Czakaj ◽

Ewelina Jarek ◽

Marcel Krzan ◽

Piotr Warszyński

Keyword(s):

Surface Tension ◽

Electrostatic Interactions ◽

Density Functional ◽

Food Packaging ◽

Prolonged Storage ◽

Adsorption Model ◽

Active Components ◽

Surfactant Mixtures ◽

Surface Active ◽

Dynamics Simulations

Ethyl lauroyl arginate (LAE) is an amino acid-based cationic surfactant with low toxicity and antimicrobial activity. It is widely used as a food preservative and component for food packaging. When stored, LAE decomposes by hydrolysis into surface-active components Nα-lauroyl–l-arginine (LAS) or dodecanoic (lauric) acid. There are only a limited number of reports considering the mechanism of surface activity of LAE. Thus, we analysed the surface tension isotherm of LAE with analytical standard purity in relation to LAE after prolonged storage. We used quantum mechanical density functional theory (DFT) computations to determine the preferred hydrolysis path and discuss the possibility of forming highly surface-active heterodimers, LAE-dodecanoate anion, or LAE-LAS. Applying molecular dynamics simulations, we determined the stability of those dimers linked by electrostatic interactions and hydrogen bonds. We used the adsorption model of surfactant mixtures to successfully describe the experimental surface tension isotherms. The real part surface dilational modulus determined by the oscillation drop method follows a diffusional transport mechanism. However, the nonlinear response of the surface tension could be observed for LAE concentration close to and above Critical Micelle Concentration (CMC). Nonlinearity originates from the presence of micelles and the reorganisation of the interfacial layer.

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Phase behavior of cationic and anionic surfactants at low concentrations

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100123878 ◽

1992 ◽

Vol 50 (1) ◽

pp. 694-695

Author(s):

E. Naranjo

Keyword(s):

Phase Behavior ◽

Structural Characterization ◽

Dynamic Systems ◽

Anionic Surfactants ◽

Intermolecular Forces ◽

Stable Form ◽

Surfactant Mixtures ◽

Low Concentrations ◽

Cationic And Anionic Surfactants ◽

General Method

Equilibrium vesicles, those which are the stable form of aggregation and form spontaneously on mixing surfactant with water, have never been demonstrated in single component bilayers and only rarely in lipid or surfactant mixtures. Designing a simple and general method for producing spontaneous and stable vesicles depends on a better understanding of the thermodynamics of aggregation, the interplay of intermolecular forces in surfactants, and an efficient way of doing structural characterization in dynamic systems.

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