Colloidal Structure and Physical Properties of Gel Networks Containing Anionic Surfactant and Fatty Alcohol Mixture

Awad, Tarek S.; Johnson, Eric S.; Bureiko, A.; Olsson, Ulf

doi:10.1080/01932691.2010.488134

Cited by 17 publications

(6 citation statements)

References 31 publications

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“…Upon cooling, a highly viscous gel network phase (ordered state) is formed with a marked increase in continuous phase viscosity. Thereby, oily droplets will be surrounded by alternating amphiphilic bilayers and interlamellar water layers, in a viscous multilamellar rearrangement [50][51][52].…”

Section: Apparent Viscositymentioning

confidence: 99%

“…Swelling properties are highly dependent on electrostatic repulsive interactions. In lipid membranes, the electrostatic repulsion enables us to incorporate significant amounts of water in the interlamellar space, once hydrogen bonds are promoted near to the hydrophilic groups, and thus phenomenal swelling, inducing changes in rheological properties [51,54]. With the increasing amphiphilic molecule concentration and thus the dispersed phase volume ratio, more gel networks are structured, since more hydrophilic groups are available to bind water molecules.…”

Section: Apparent Viscositymentioning

confidence: 99%

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Progressing Towards the Sustainable Development of Cream Formulations

2020

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This work aims at providing the assumptions to assist the sustainable development of cream formulations. Specifically, it envisions to rationalize and predict the effect of formulation and process variability on a 1% hydrocortisone cream quality profile, interplaying microstructure properties with product performance and stability. This tripartite analysis was supported by a Quality by Design approach, considering a three-factor, three-level Box–Behnken design. Critical material attributes and process parameters were identified from a failure mode, effects, and criticality analysis. The impact of glycerol monostearate amount, isopropyl myristate amount, and homogenization rate on relevant quality attributes was estimated crosswise. The significant variability in product droplet size, viscosity, thixotropic behavior, and viscoelastic properties demonstrated a noteworthy influence on hydrocortisone release profile (112±2-196±7 μg/cm2/√h) and permeation behavior (0.16±0.03-0.97±0.08 μg/cm2/h), and on the assay, instability index and creaming rate, with values ranging from 81.9 to 120.5%, 0.031±0.012 to 0.28±0.13 and from 0.009±0.000 to 0.38±0.07 μm/s, respectively. The release patterns were not straightforwardly correlated with the permeation behavior. Monitoring the microstructural parameters, through the balanced adjustment of formulation and process variables, is herein highlighted as the key enabler to predict cream performance and stability. Finally, based on quality targets and response constraints, optimal working conditions were successfully attained through the establishment of a design space.

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Section: Apparent Viscositymentioning

confidence: 99%

Section: Apparent Viscositymentioning

confidence: 99%

Progressing Towards the Sustainable Development of Cream Formulations

2020

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“…It is interesting to note, however, that in addition to the Maltese crosses, there are crystal-like structures that are seen in the polarised light images of the cream formulations containing just hexadecanol (C5; Figure 1 b) or octadecanol (C6; Figure 1 c) co-surfactant. Whilst in these one-day-old preparations, there are relatively few crystals seen in the cream containing just hexadecanol as co-surfactant, there are large numbers of crystals seen in the micrograph for the cream containing octadecanol ( Figure 1 c), which suggests that when this latter preparation is cooled, there is excess octadecanol present that does not go to surround the oil droplets and is not incorporated in the bilayers of the gel network, and instead forms non-swollen crystallite structures [ 25 ].…”

Section: Resultsmentioning

confidence: 99%

The Influence of Co-Surfactants on Lamellar Liquid Crystal Structures Formed in Creams

et al. 2020

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It is well-established that oil-in-water creams can be stabilised through the formation of lamellar liquid crystal structures in the continuous phase, achieved by adding (emulsifier) mixtures comprising surfactant(s) combined (of necessity) with one or more co-surfactants. There is little molecular-level understanding, however, of how the microstructure of a cream is modulated by changes in co-surfactant and of the ramifications of such changes on cream properties. We investigate here the molecular architectures of oil-free, ternary formulations of water and emulsifiers comprising sodium dodecyl sulfate and one or both of the co-surfactants hexadecanol and octadecanol, using microscopy, small-angle and wide-angle X-ray scattering and small-angle neutron scattering. We then deploy these techniques to determine how the structures of the systems change when liquid paraffin oil is added to convert them to creams, and establish how the structure, rheology, and stability of the creams is modified by changing the co-surfactant. The ternary systems and their corresponding creams are shown to contain co-surfactant lamellae that are subtly different and exhibit different thermotropic behaviours. The lamellae within the creams and the layers surrounding their oil droplets are shown to vary with co-surfactant chain length. Those containing a single fatty alcohol co-surfactant are found to contain crystallites, and by comparison with the cream containing both alcohols suffer adverse changes in their rheology and stability.

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“…The density of D 2 O is ca. 1.1 g/cm 3 . This means that the volume fraction of CTAC and CA together ≈0.13.…”

Section: Sample Preparationmentioning

confidence: 95%

“…Long-chain fatty alcohols, such as stearyl alcohols, are generally combined with long-chain quaternary ammonium surfactants such as cetyltrimethylammonium chloride (CTAC) in formulations of conditioners. [1][2][3].…”

Section: Introductionmentioning

confidence: 99%