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The effect of temperature on in situ β-cyclodextrin inclusion complex aggregate films at liquid-liquid interfaces
Journal article   Open access   Peer reviewed

The effect of temperature on in situ β-cyclodextrin inclusion complex aggregate films at liquid-liquid interfaces

Oisín Owens, Benjamin T. Lobel, Stuart Micklethwaite, Saijel Jani, Ian Harrison, David Harbottle and Olivier J. Cayre
Journal of colloid and interface science, Vol.722, 140846
2026
DOI: https://doi.org/10.1016/j.jcis.2026.140846
PMID: 42241881
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Open Access CC BY V4.0

Abstract

Cyclodextrin Emulsions Formation constant Inclusion complex Interfacial film Temperature
The stability of β-cyclodextrin (β-CD)-oil inclusion complex (IC) interfacial films observed on emulsion droplets is enhanced by the binding affinity (or formation constant, Kf) of the ‘guest’ oil molecule to the β-CD cavity. Changes to the surrounding environment, such as temperature increase or dilution, are expected to shift the complexation equilibrium leading to interfacial film desorption/dissolution. It is postulated that the relative response of the films is due to the enhanced host-guest binding strength counteracting shifts to the complexation equilibrium that lead to destabilisation, thus providing a framework for carefully tuning emulsion stability. Oil-in-water emulsions stabilised by β-CD were formulated for a series of oil types with increasing alkane chain length and structural complexity (providing a range of Kf values) across increasing β-CD concentrations. Emulsion behaviour during temperature increase was examined quantitively using ion-exchange chromatography and under direct observation in cryo-scanning electron microscopy (cryo-SEM). Interfacial shear rheology equipped with a double wall ring (DWR) geometry, was then used to examine the elastic response of the interfacial films to temperature increase. β-CD ICs laden films showed a decrease in interfacial shear elastic modulus with increasing temperature indicating that the film desorbs/dissociates once a critical temperature is reached. This effect is diminished by increasing the β-CD concentration or by utilising oils of higher Kf value (eucalyptol > hexadecane >n-dodecane >n-decane). The corresponding improved emulsion thermal stability was further linked to a higher adsorption of available ICs to the interface, which retain their particle-like configuration upon heating within the range of temperatures tested. [Display omitted]

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