Temperature-sensitive properties of occluded hydration centers in direct hexagonal (HI) mesophases
Temperature-induced structural transformations of a direct hexagonal mesophase were investigated by SAXS, rheology, DSC, and NMR. The investigated mesophase region consists of two distinct direct hexagonal structures. The primary structure, detected at lower water content (33.0–39.0 wt%, 25 °C), is...
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Veröffentlicht in: | Colloids and surfaces. A, Physicochemical and engineering aspects Physicochemical and engineering aspects, 2021-12, Vol.631, p.127709, Article 127709 |
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Sprache: | eng |
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Zusammenfassung: | Temperature-induced structural transformations of a direct hexagonal mesophase were investigated by SAXS, rheology, DSC, and NMR. The investigated mesophase region consists of two distinct direct hexagonal structures. The primary structure, detected at lower water content (33.0–39.0 wt%, 25 °C), is oriented as a bidiscontinuous assembly; it is composed of "occluded hydration centers" (OHCs) and direct surfactant-oil aggregates. The secondary structure, detected at higher water content (39.5–42.5 wt% water, 25 °C), is composed of an unbound water continuous phase and direct surfactant-oil aggregates.
The OHCs within the bidiscontinuous mesophase were found to enhance the mesophase's order (correlation length (ξ)) and storage modulus (G′). The content of the unbound water occluded within the OHCs is temperature dependent, due to the ethoxylates’ water binding properties. At temperatures below 18 °C, the water in the bidiscontinuous mesophase ( |
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ISSN: | 0927-7757 1873-4359 |
DOI: | 10.1016/j.colsurfa.2021.127709 |