Surfactant-enhanced spreading: Experimental achievements and possible mechanisms

Kovalchuk, N. M.; Trybała, Anna; Arjmandi-Tash, Omid; Starov, Victor

doi:10.1016/j.cis.2015.08.001

Cited by 49 publications

(29 citation statements)

References 44 publications

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“…The most probable candidates are: the 'caterpillar-like' motion at the moving three-phase contact line, providing lower energy dissipation [10]; bilayer formation at the leading edge of spreading [11,12]; and Marangoni flow [13,14]. The comprehensive discussion on all these mechanisms is given in Ref [15].…”

Section: /Smentioning

confidence: 99%

The effect of adsorption kinetics on the rate of surfactant-enhanced spreading

et al. 2016

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A comparison of the kinetics of spreading of aqueous solutions of two different surfactants on the identical substrate and their short time adsorption kinetics at the water/air interface has shown that the surfactant which adsorbs slower provides a higher spreading rate. This observation indicates that Marangoni flow should be an important part of the spreading mechanism enabling surfactant solutions to spread much faster than pure liquids with comparable viscosities and surface tensions.

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Section: /Smentioning

confidence: 99%

The effect of adsorption kinetics on the rate of surfactant-enhanced spreading

et al. 2016

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“…Surfactants are commonly included in spray formulations to improve the retention and spreading of droplets, especially when the target is difficult-to-wet (Gaskin et al, 2005). The droplet impact and spreading of surfactant-laden formulations is complicated and the possible mechanisms are still being debated (Gatne et al, 2009;Ivanova and Starov, 2011;Kovalchuk et al, 2016). The effects that leaf surface roughness and chemistry have on the liquid dynamic wetting, and subsequently on the droplet impaction outcomes such as adhesion, bounce or shatter, are still not fully defined.…”

Section: Introductionmentioning

confidence: 99%

Spray droplet impaction outcomes for different plant species and spray formulations

et al. 2017

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A track-sprayer combined with a high-speed camera were used to visualize and identify droplet impaction outcomes for three formulations (water, 0.1% LI 700® (lecithin, a mixture of soya oils, propionic acid and surfactants) in water and 0.1% Pulse® (non-ionic surfactant, trisiloxane ethoxylate) in water) on four plant species (bean (Vicia faba L.), avocado (Persea americana L.), barnyard grass (Echinochloa crus-galli L. P. Beauv.) and cabbage (Brassica oleracea L.)) selected to represent a wide range of leaf surface characters. Droplet sizes and velocities were measured by image analysis and a multiple hypothesis tracking algorithm. Impaction outcomes were categorized into adhesion, bounce, or shatter. The probability of each outcome was estimated from logistic regression models related to the dimensionless Weber number. This approach is in contrast to various deterministic threshold criteria for droplet bounce or shatter that have been used to model droplet impaction events on leaves. It also provides a simple visual and numerical presentation of the complexity of impaction processes, and the relative influence of leaf surface character versus formulation for droplets with different impaction energies.

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“…The central droplet surface therefore moved outwards and spread onto the substrate until the gradient reduced. A detailed discussion of theoretical arguments supporting the Marangoni effect mechanism together with experimental evidence has been given in previous studies [16,49,51]. The formation of surface tension gradients resulting in the Marangoni effect was also observed in numerical simulations [55].…”

Section: Dynamic Spreading Behavior Of the Surfactants On Plant Leaf mentioning

confidence: 98%

A gemini-type superspreader: Synthesis, spreading behavior and superspreading mechanism

Lin

Wang

Bai

et al. 2017

Chemical Engineering Journal

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Please cite this article as: A gemini-type superspreader: synthesis, spreading behavior and superspreading mechanism, Chemical Engineering Journal (2016), doi: http://dx.doi.org/10. 1016/j.cej.2016.12.132 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain. ABSTRACTThis paper describes the facile microwave-assisted synthesis of a series of trisiloxane gemini superspreaders, as well as their surface and aggregation properties and superspreading behavior on plant leaf surfaces. The molecular structures of the trisiloxane gemini surfactants were characterized by Fourier transform infrared spectroscopy (FTIR) and 1 H nuclear magnetic resonance spectroscopy ( 1 H NMR). The obtained thermodynamic parameters showed that an increase in the spacer group (CH 2 ) resulted in decreases in the critical aggregation concentration (CAC), corresponding surface tension (γ CAC ), and surface excess concentration (Γ max ) but increases in the occupied area per surfactant molecule (A CAC ) and absolute values of the standard free energies of aggregation (△G θ mic ) and adsorption (△G θ ads ). An increase in ethoxy units (CH 2 -CH 2 -O-) resulted in increases in the CAC, γ CAC , and A CAC but decreases in Г max and the absolute values of △G θ mic and △G θ ads . The transmission electron microscopy and dynamic light scattering results showed that the average sizes of the aggregates of superspreader solutions increased with an increasing number of spacer units (CH 2 ) but decreased with an increasing number of ethoxy units (CH 2 -CH 2 -O-). The dynamic spreading behavior results demonstrated that the average spreading velocity increased with increasing spacer chain length, and the dependence of the maximum spreading velocity on the ethoxy chain length was nonmonotonous with a maximum at n(EO) = 8.68. The optimal HLB value was essential to obtaining good superspreading behavior, and the substrate wettability (hydrophobic rice plant and hydrophilic mango plant surfaces) greatly influenced the superspreading. The synergistic effects from the precursor film and Marangoni effect existed in the proposed superspreading model.

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Surfactant-enhanced spreading: Experimental achievements and possible mechanisms

Cited by 49 publications

References 44 publications

The effect of adsorption kinetics on the rate of surfactant-enhanced spreading

The effect of adsorption kinetics on the rate of surfactant-enhanced spreading

Spray droplet impaction outcomes for different plant species and spray formulations

A gemini-type superspreader: Synthesis, spreading behavior and superspreading mechanism

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