Phase equilibria and structures in ternary systems of a cationic surfactant (C16 TABr or (C16 TA)2SO4), alcohol, and water

Fontell, Krister; Khan, Ali; Lindström, Birger; Maciejewska, Dorota; Puang-Ngern, Srisuda

doi:10.1007/bf00657411

Cited by 149 publications

(197 citation statements)

References 34 publications

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“…In the hexagonal phase of CTAB, there is an area per headgroup of 53 Å 2 and a cylinder diameter of 43 Å. 39 This means that, projected on the cylinder axis, there is one charge per 0.36 Å. Surfactant aggregates are formed by a self-assembly process so that under different conditions one can expect adjustments in these numbers, but there should not occur major changes; a change in headgroup area exceeding, for example, 20% appears unlikely. For DNA, there are more fixed atomic positions in the double helix so the structure is locally stiffer.…”

Section: Discussionmentioning

confidence: 99%

The Hydration of a DNA−Amphiphile Complex

et al. 2004

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We present measurements of isothermal DNA-hexadecyltrimethylammonium (DNACTA) complex and pure DNA hydration at 25°C using a sorption microcalorimeter. This calorimeter provides simultaneous measurement of (i) water activity (sorption isotherms) and (ii) the partial molar enthalpy of water as a function of water uptake. For pure DNA, hydration is exothermic over the studied concentration range and we find an approximately linear relation between the partial molar enthalpy and the partial molar free energy. A kink in the isotherm appears at 20.0 ( 0.3 water molecules per base pair for a water activity of 0.80, consistent with A-B transition of the DNA. There is no detectable heat effect associated with this transition. At low water contents, the hydration of the DNACTA (1:1) complex is exothermic as for the pure DNA, but after incorporation of the first 7.0 ( 0.1 water molecules, the enthalpy changes sign. At 22 water molecules per base pair, the enthalpy levels off to 2.7 ( 0.2 kJ/mol. In a separate experiment, the swelling limit for the DNACTA complex was found to be 27 ( 1 waters per base pair. The DNACTA complex is arranged in a hexagonal structure. We propose a model for the DNACTA complex based on the packing of the components in an electroneutral way consisting of six DNA helices, presumably in an A configuration, placed around a central CTA + cylinder. The hydration of the complex is seen as a balance between the attractive electrostatic interaction causing the formation of the complex and a repulsive component arising from a hexagonal deformation of CTA + cylinders. An important contribution to the partial molar enthalpy of water comes, in this interpretation, from the release of conformational constraints of the CTA ion alkyl chains.

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Section: Discussionmentioning

confidence: 99%

The Hydration of a DNA−Amphiphile Complex

et al. 2004

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“…In particular, the phase diagrams of CTAB/ cetylpyridinium chloride/1-BuOH/water system designed to aliphatic alcohol/water systems, which demonstrate that the elucidate the influence of the surfactant head group on the chain length of the alcohol decisively affects the phase diaphase diagrams. A conductivity study of the L phase has gram, are well established (3)(4)(5)(6). In the ternary systems been carried out in order to compare the results found in formed by the short chain alcohols (ranging from methanol other ternary systems, such as CTAB/PPG/H 2 O (8), to butanol) a transparent, isotropic, and low viscous phase CTAB/1-BuOH/H 2 O (13), CTAB/1-HexOH/H 2 O (14), appears, which extends from the water-rich corner to the SDS/PPG/H 2 O (9), and SDS/alcohol/H 2 O (15).…”

Section: Introductionmentioning

confidence: 99%

A Phase Diagram of theN-Cetylpiridinium Chloride/1-BuOH/Water Ternary System

Molinero

Sierra

Rodenas

1997

Journal of Colloid and Interface Science

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“…Pentanol exhibits low water solubility, at approximately 22g/L. Ternary systems of CTAB (hexadecyl-trimethyl-ammonium bromide)/alcohol/water have been studied extensively and the phase diagrams mapped in detail, 33,34 providing useful analogs to CTAC phase behaviour. The ternary system of 17.4 wt% C 16 TAC, 20 wt% C 5 OH and 62.6% H 2 O, self-assembles into a lamellar L α mixed phase (with excess water) at equilibrium, as shown below (although wormlike micelles are wellknown to form in aqueous CTAC solutions in the presence of salt 35 ).…”

Section: Methodsmentioning

confidence: 99%

Microfluidic processing of concentrated surfactant mixtures: online SAXS, microscopy and rheology

et al. 2016

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We investigate the effect of microfluidic flow on the microstructure and dynamics of a model surfactant mixture, combining synchrotron Small Angle X-ray Scattering (SAXS), microscopy and rheology. A system comprising a single-chain cationic surfactant, hexadecyl trimethyl ammonium chloride (C 16 TAC), a short-chain alcohol (1-pentanol) and water was selected for the study due to its flow responsiveness and industrial relevance. Model flow fields, including sequential contraction-expansion (extensional) and rotational flows, were investigated and the fluid response in terms of the lamellar d-spacing, orientation and birefringence was monitored in situ, as well as the recovery processes after cessation of flow. Extensional flows are found to result in considerable d-spacing increase (from approx 59Å to 65Å). However, under continuous flow, swelling decreases with increasing flow velocity, eventually approaching the equilibrium values at velocities 2 cms −1 . Through individual constrictions we observe the alignment of lamellae along the flow velocity, accompanied by increasing birefringence, followed by an orientation flip whereby lamellae exit perpendicularly to the flow direction. The resulting microstructures are mapped quantitatively onto the flow field in 2D with 200 µm spatial resolution. Rotational flows alone do not result in appreciable changes in lamellar spacing and flow type and magnitude evidently impact the fluid microstructure under flow, as well as upon relaxation. The findings are correlated with rheological properties measured ex-situ to provide a mechanistic understanding of the effect of flow imposed by tubular processing units in the phase behavior and performance of a model surfactant system with ubiquitous applications in personal care and coatings industries.

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Phase equilibria and structures in ternary systems of a cationic surfactant (C16 TABr or (C16 TA)2SO4), alcohol, and water

Cited by 149 publications

References 34 publications

The Hydration of a DNA−Amphiphile Complex

The Hydration of a DNA−Amphiphile Complex

A Phase Diagram of theN-Cetylpiridinium Chloride/1-BuOH/Water Ternary System

Microfluidic processing of concentrated surfactant mixtures: online SAXS, microscopy and rheology

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