Microstructure evolution during nano-emulsification by NMR and microscopy

JOURNAL OF COLLOID AND INTERFACE SCIENCE

卷:551

Article

D'Agostino, Carmine¹  Preziosi, Valentina²  Khan, Abdulaziz³  Mantle, Mick³  Fridjonsson, Einar⁴  Guido, Stefano² 

[1] Univ Manchester, Mill, Sch Chem Engn & Analyt Sci, Sackville St, Manchester M13 9PL, Lancs, England

[2] Univ Napoli Federico II, UdR INSTM, Dipartimento Ingn Chim Mat & Prod Ind, Ple Tecchio 80, I-80125 Naples, Italy

[3] Univ Cambridge, Dept Chem Engn & Biotechnol, Philippa Fawcett Dr,West Cambridge Site, Cambridge CB3 0AS, England

[4] Univ Western Australia, Dept Chem Engn, 35 Stirling Highway, Crawley, WA, Australia

关键词: Nano-emulsions;    PFG NMR;    Diffusion;    CLSM;    Phase inversion emulsification;   

DOI  :  10.1016/j.jcis.2019.04.098

来源: Elsevier

【 摘 要 】

Hypothesis: Microstructure evolution in emulsions as a function of composition is of great interest but fundamentals have not yet been fully elucidated. Here, pulsed-field gradient (PFG) NMR diffusion measurements have been combined with confocal laser scanning microscopy (CLSM) to assess evolution of dynamics and microstructure during nano-emulsification. Experiments: Diffusion coefficients of emulsions made of water, mineral oil and surfactants (Span 20 and Tween 80) were measured as a function of water composition and compared with the morphological features of the emulsions obtained by CLSM. Findings: In the absence of water, two phases are visible from CLSM, and two diffusion components are observed with PFG NMR, a major fast component attributed to a continuous oil phase containing the more hydrophobic surfactant Span 20 with traces of Tween 80, and a minor slow component attributed to a dispersed phase of the more hydrophilic surfactant Tween 80 with traces of mineral oil and Span 20. At the inversion point (25 wt% water) the two-component diffusion behavior of the oil-rich phase is drastically reversed in terms of populations, with the slow diffusion process becoming dominant. This suggests a significant structuring of the oil-rich phase in the presence of surfactants enhanced by water, which can be explained by the formation of aggregates in the oil phase as reverse micelles or of a lamellar structure, and ties in well with the rheological measurements. (C) 2019 Elsevier Inc. All rights reserved.

【 授权许可】

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