Mechanical phase inversion of Pickering emulsions via metastable wetting of rough colloids
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Date
2019-10-21
Publication Type
Journal Article
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yes
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Abstract
The possibility to invert emulsions from oil-in-water to water-in-oil (or vice versa) in a closed system, i.e. without any formulation change, remains an open fundamental challenge with many opportunities for industrial applications. Here, we propose a mechanism that exploits particle surface roughness to induce metastable wetting and obtain mechanically-responsive Pickering emulsions. We postulate that the phase inversion is driven by an in situ switch of the particle wettability from metastable positions at the interface following the input of controlled mechanical energy. Oil-in-water emulsions can be prepared at low energy using mildly hydrophobic rough colloids, which are dispersed in water and weakly pinned at the interface, and switched to water-in-oil emulsions by a second emulsification at higher energy, which triggers the relaxation of the particle contact angle. The same principle is demonstrated for the complementary emulsions using mildly hydrophilic colloids initially dispersed in oil. Our experiments and simulations support that the delicate interplay between particle surface design during synthesis and the energy of the emulsification process can encode a kinetic pathway for the phase inversion. Both organic and inorganic nanoparticles can be used, allowing for the future implementation of our strategy in a broad range of smart industrial formulations.
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published
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Volume
15 (39)
Pages / Article No.
7888 - 7900
Publisher
Royal Society of Chemistry
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03451 - Morbidelli, Massimo (emeritus) / Morbidelli, Massimo (emeritus)
09455 - Isa, Lucio / Isa, Lucio
03832 - Morgenroth, Eberhard / Morgenroth, Eberhard
09717 - Mitrano, Denise M. (ehemalig) / Mitrano, Denise M. (former)
Notes
Funding
144646 - Two-dimensional self-assembled materials at liquid interfaces: basics, shear and patches (SNF)
172913 - Complex colloids assembled using capillary interactions: a new route towards active materials (SNF)
172913 - Complex colloids assembled using capillary interactions: a new route towards active materials (SNF)