Surfactant-enhanced spreading: Experimental achievements and possible mechanisms

Surfactants are broadly used to improve wetting properties of aqueous formulations. The improvement is achieved by essential reduction of liquid/air and solid/liquid interfacial tensions resulting in the decrease of contact angle. For moderately hydrophobic substrates, there is a range of surfactant...

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Bibliographic Details
Published in:Advances in colloid and interface science 2016-07, Vol.233, p.155-160
Main Authors: Kovalchuk, N.M., Trybala, A., Arjmandi-Tash, O., Starov, V.
Format: Article
Language:English
Subjects:
Aqueous surfactant solutions
Complete wetting
Formulations
Hydrophobic substrates
Interfacial tension
Liquids
Polypropylenes
Spreading
Spreading factor
Spreading kinetics
Substrates
Surface energy
Surfactants
Wetting
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Summary:Surfactants are broadly used to improve wetting properties of aqueous formulations. The improvement is achieved by essential reduction of liquid/air and solid/liquid interfacial tensions resulting in the decrease of contact angle. For moderately hydrophobic substrates, there is a range of surfactants providing complete wetting of substrate. With the decrease of substrate surface energy, this range of surfactants reduces very quickly and only trisiloxane surfactant solutions are capable to wet completely such highly hydrophobic substrates as polypropylene and parafilm. That is why these surfactants are referred to as superspreaders. The most intriguing feature of wetting surfactant solutions is their ability to spread much faster than pure liquids with spread area, S, being proportional to time, t, S~t, as compared to S~t0.2 for pure liquids, which wet completely the solid substrate. Trisiloxane surfactant solutions spread faster than other aqueous surfactant solutions, which also provide complete wetting, being superspreaders in the sense of spreading rate as well. The mechanism of fast spreading of surfactant solutions on hydrophobic substrates and much higher spreading rates for trisiloxane solutions are to be explained. Below the available experimental data on superspreading and surfactant-enhanced spreading are analysed/summarised, and possible mechanisms governing the fast spreading are discussed. [Display omitted] •Comparison of spreading performance of various surfactants•Possible mechanisms of fast spreading of surfactant solutions on hydrophobic substrates•Available experimental data on superspreading and surfactant-enhanced spreading•Synergism in spreading of mixed solutions of cationic and anionic surfactants
ISSN:0001-8686
1873-3727
DOI:10.1016/j.cis.2015.08.001