The aggregation in dodecyltrimethylammonium hydroxide aqueous solutions

Schulz, Pablo C.; Morini, Marcela A.; Minardi, R. M.; Puig, J. E.

doi:10.1007/bf00660374

Cited by 17 publications

(12 citation statements)

References 35 publications

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“…Water used in all prepared solutions refers to Milli-Q water with a conductivity of 18 MΩ cm –1 . Didodecyldimethylammonium hydroxide (DDAOH) was prepared using previously reported methods. ,,, The successful conversion of bromide to hydroxide was verified using electrospray ionization mass spectrometry analysis to confirm the absence of the bromide ion and (DDA + ) n +1 OH n clusters.…”

Section: Methodsmentioning

confidence: 99%

Self-Assembly of Didodecyldimethylammonium Surfactants Modulated by Multivalent, Hydrolyzable Counterions

Liu

Warr

2014

Langmuir

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The self-assembly behavior of double-chained didodecyldimethylammonium (DDA(+)) surfactants with hydrolyzable phosphate (PO4(3-), HPO4(2-), and H2PO4(-)), oxalate (HC2O4(-) and C2O4(2-)), and carbonate (HCO3(-)/CO3(2-)) counterions was found to depend on both the counterion and its hydrolysis state, as determined by the pH of the system. Carbonate and phosphate ions at all hydrolysis states successfully stabilize an extended isotropic micellar solution region. These micelles are well-described as prolate ellipsoids which vary in size and aspect ratio depending on the surfactant concentration and hydrolysis state of the counterion. Both oxalate counterions form bilayer structures in dilute solution. The structures found with divalent oxalate, C2O4(2-), ions possessed very limited swelling capacity compared to the bilayer structures formed with monovalent oxalate, HC2O4(-), ions. The lamellar (Lα) phase was universally formed at sufficiently high surfactant concentrations for all hydrolyzable counterions. Two intermediate structures corresponding to a disordered mesh (Lα(D)) and tetragonal ordered mesh (T) phase were found to form with DDA2HPO4 prior to the Lα phase but not with other phosphate counterions.

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Section: Methodsmentioning

confidence: 99%

Self-Assembly of Didodecyldimethylammonium Surfactants Modulated by Multivalent, Hydrolyzable Counterions

Liu

Warr

2014

Langmuir

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“…Water used in all prepared solutions refers to Milli-Q water with a conductivity of 18 MΩ cm –1 . Alkyltrimethylammonium hydroxides (XTAOH) were prepared using previously reported methods. ,− Specifically, XTAB was ion exchanged to XTAOH using Amberlite IRA-400(OH) (Supelco) exchange resin. The successful conversion of bromide to hydroxide was verified using a nitric acid (HNO 3 ) and 0.1 M silver nitrate (Ajax Finechem) solution.…”

Section: Methodsmentioning

confidence: 99%

Resiliently Spherical Micelles of Alkyltrimethylammonium Surfactants with Multivalent, Hydrolyzable Counterions

Liu

Warr

2012

Langmuir

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A series of C(12)-C(16) alkyltrimethylammonium surfactants with hydrolyzable phosphate (PO(4)(3-), HPO(4)(2-), and H(2)PO(4)(-)), oxalate (HC(2)O(4)(-) and C(2)O(4)(2-)), and carbonate (HCO(3)(-) and CO(3)(2-)) counterions have been prepared, and their micellar solution behavior has been characterized. Critical micelle concentrations were measured using electrical conductivity and were found to depend on both the counterion and its hydrolysis state. All monovalent counterions bind less strongly to the micelle surface than does bromide or chloride, whereas multivalent species bind more strongly. Small-angle neutron scattering reveals that, unlike alkyltrimethylammonium bromides and chlorides, micelles are small and spherical in the presence of hydrolyzable counterions of all valences and remain spherical even in the presence of added electrolyte. This is consistent with the strong solvation of even strongly bound hydrolyzable counterions, which prevents the screening of repulsions between adjacent headgroups necessary for sphere-cylinder transformations. Salts of multivalent hydrolyzable counterions could thus be used to control the micelle structure in novel ways.

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“…A precedent of a similar misinterpretation based on single technique measurements occurred with alkyltrimethylammonium hydroxides. 33 The transition concentration values observed from the battery of experimental techniques employed in the present work are summarized in Table 1. The average values of these concentrations together with the expected associated processes are: (a) the formation of premicelles with some capacity to solubilize dyes (0.05 mM); (b) formation of spherical micelles which immediately grow to form disk-like micelles (0.260 ± 0.023 mM); (c) undetermined structure transition of the disklike micelles (0.346 ± 0.033 mM); (d) destabilization of the disk-like micelles (0.454 ± 0.066 mM); (e) formation of the lamellar mesophase emulsion (0.670 ± 0.045 mM); and (c) undetermined transition (0.127 ± 0.023 mM).…”

Section: ■ Experimental Sectionmentioning

confidence: 99%

Intermediate Structures for Higher Level Arrangements: Catching Disk-Like Micelles in Decane Phosphonic Acid Aqueous Solutions

et al. 2013

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It has been proposed that disk-like micelles may be precursors to the formation of lamellar liquid crystals. The possibility of obtaining n-decane phosphonic acid (DPA) disk-like micelles in aqueous solution without the addition of a second ionic surfactant led us to study in detail the low-concentration range of this system by both a battery of experimental techniques and molecular dynamics (MD) simulations. The experimental results indicate that premicelles with some capacity to solubilize dyes are formed at 0.05 mM. The critical micelle concentration (cmc) was found to be 0.260 ± 0.023 mM, much lower than that previously reported in the literature. Spherical micelles, which immediately grow, leading to disk-like micelles, are probably formed at this concentration. At 0.454 ± 0.066 mM, disk-like micelles become unstable, giving rise to the formation of an emulsion of lamellar mesophase that dominates the system beyond 0.670 ± 0.045 mM. These experimental results were corroborated by MD simulations which, additionally, allow describing the structure of the obtained micelles at atomic level. The analysis of the MD trajectories revealed the presence of strong intermolecular hydrogen bonds between the surfactant headgroups, producing a compact polar layer with low water content. The formation of such H-bond network could explain the ability of this surfactant to form disk-like micelles at concentrations close to the cmc.

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The aggregation in dodecyltrimethylammonium hydroxide aqueous solutions

Cited by 17 publications

References 35 publications

Self-Assembly of Didodecyldimethylammonium Surfactants Modulated by Multivalent, Hydrolyzable Counterions

Self-Assembly of Didodecyldimethylammonium Surfactants Modulated by Multivalent, Hydrolyzable Counterions

Resiliently Spherical Micelles of Alkyltrimethylammonium Surfactants with Multivalent, Hydrolyzable Counterions

Intermediate Structures for Higher Level Arrangements: Catching Disk-Like Micelles in Decane Phosphonic Acid Aqueous Solutions

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