Title Assessing differences between Ostwald ripening and coalescence by rheology, laser diffraction and multiple light scattering
Authors SANTOS GARCÍA, JENIFER, Calero, N. , Trujillo-Cayado, L. A. , Garcia, M. C. , Munoz, J.
External publication Si
Means Colloid Surf. B-Biointerfaces
Scope Article
Nature Científica
JCR Quartile 1
SJR Quartile 1
JCR Impact 3.99700
SJR Impact 1.07100
Publication date 01/11/2017
ISI 000418729600046
DOI 10.1016/j.colsurfb.2017.08.015
Abstract This contribution deals with the study of the influence of surfactant ratio, namely triblock copolymer (Pluronic PE9400) to polyoxyethylene glycerol fatty acid ester (Levenol C201), on the stability of emulsions formulated with a mixture of two biosolvents (N,N Dimethyl Decanamide and D-limonene), which find applications as carriers of agrochemicals. Emulsions containing Pluronic, regardless of the concentration studied, underwent Ostwald ripening while coalescence controlled the destabilization process of emulsions containing Levenol C201 as the only emulsifier. The physical stability of the emulsions was analysed not only by means of mean diameters determined by laser diffraction but also with respect to their rheological properties and the so-called TSI parameter derived from multiple light scattering measurements with aging time. We propose that the different structures of both surfactants at the oil/water interface may be responsible for the occurrence of different destabilization mechanisms. It is likely that Copolymer Pluronic PE9400 formed multilayers in the emulsions studied, which may promote flocculation during processing and, subsequently, Ostwald ripening. In contrast, Levenol C201 probably formed a compact adsorbed layer with the molecules perpendicularly oriented to the interface. This work illustrates to what extent the combination of information provided by Multiple Light Scattering, rheology and laser diffraction enables the detection and monitoring of destabilization mechanisms such as Ostwald ripening and coalescence. In addition, this research highlights the importance of surfactant selection for the physical stability of emulsions that exhibited similar droplet size distributions just after preparation. (C) 2017 Elsevier B.V. All rights reserved.
Keywords Eco-friendly emulsions; Flocculated emulsions; Applied rheology; Ostwald ripening; Coalescence
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