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Quantification of counterion binding to and its effects on aqueous dispersions of dialkyl cationic surfactants

Lorenz De Neve (UGent) , Lien Vermeir (UGent) , Paolo Sabatino (UGent) , Pieter Saveyn, Quenten Denon (UGent) , José Martins (UGent) and Paul Van Der Meeren (UGent)
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Abstract
Dialkyl cationic surfactants, such as dioctadecyl dimethyl ammonium bromide (DODAB) form vesicles upon dispersion in water. In order to study the influence of the surfactant's counterion, the same dialkyl surfactant was prepared with a fluoride counterion (DODAF). Visually, quite transparent dispersions were prepared when fluoride was selected as counterion, whereas more turbid dispersions were obtained using the bromide surfactant. LR-NMR revealed that the permeability of the DODAF dispersions for water was much larger, which indicated that these rather contained uni-or oligolamellar vesicles, whereas the DODAB dispersions were multilamellar. These observations seemed to indicate an increasing degree of surface charge neutralization by the heavier anions, in line with the Hofmeister series, which was indeed confirmed by electrophoretic light scattering measurements. In order to further quantify the surfactant-counterion interaction, HR-NMR diffusometry measurements were performed on dispersions of a dialkyl cationic surfactant with methyl sulphate counterion in deuterated water. The diffusion data showed that the mobility of this organic anion increased when adding different sodium halides, with a stronger effect from fluoride over chloride and bromide to iodide, which clearly indicated the gradual displacement of the methyl sulphate counterion from the vesicular surface by the stronger binding anions.
Keywords
Vesicles, Counterion binding, NMR, Cationics, VESICULAR DISPERSIONS, FABRIC SOFTENERS, VESICLES, TRANSITIONS, SULFATE, HALIDES, CHAIN, PH

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Chicago
De Neve, Lorenz, Lien Vermeir, Paolo Sabatino, Pieter Saveyn, Quenten Denon, José Martins, and Paul Van Der Meeren. 2017. “Quantification of Counterion Binding to and Its Effects on Aqueous Dispersions of Dialkyl Cationic Surfactants.” Colloids and Surfaces A-physicochemical and Engineering Aspects 532: 458–463.
APA
De Neve, Lorenz, Vermeir, L., Sabatino, P., Saveyn, P., Denon, Q., Martins, J., & Van Der Meeren, P. (2017). Quantification of counterion binding to and its effects on aqueous dispersions of dialkyl cationic surfactants. COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS, 532, 458–463. Presented at the 30th Meeting of the European Colloid and Interface Society (ECIS).
Vancouver
1.
De Neve L, Vermeir L, Sabatino P, Saveyn P, Denon Q, Martins J, et al. Quantification of counterion binding to and its effects on aqueous dispersions of dialkyl cationic surfactants. COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS. 2017;532:458–63.
MLA
De Neve, Lorenz, Lien Vermeir, Paolo Sabatino, et al. “Quantification of Counterion Binding to and Its Effects on Aqueous Dispersions of Dialkyl Cationic Surfactants.” COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS 532 (2017): 458–463. Print.
@article{8521085,
  abstract     = {Dialkyl cationic surfactants, such as dioctadecyl dimethyl ammonium bromide (DODAB) form vesicles upon dispersion in water. In order to study the influence of the surfactant's counterion, the same dialkyl surfactant was prepared with a fluoride counterion (DODAF). Visually, quite transparent dispersions were prepared when fluoride was selected as counterion, whereas more turbid dispersions were obtained using the bromide surfactant. LR-NMR revealed that the permeability of the DODAF dispersions for water was much larger, which indicated that these rather contained uni-or oligolamellar vesicles, whereas the DODAB dispersions were multilamellar. These observations seemed to indicate an increasing degree of surface charge neutralization by the heavier anions, in line with the Hofmeister series, which was indeed confirmed by electrophoretic light scattering measurements. In order to further quantify the surfactant-counterion interaction, HR-NMR diffusometry measurements were performed on dispersions of a dialkyl cationic surfactant with methyl sulphate counterion in deuterated water. The diffusion data showed that the mobility of this organic anion increased when adding different sodium halides, with a stronger effect from fluoride over chloride and bromide to iodide, which clearly indicated the gradual displacement of the methyl sulphate counterion from the vesicular surface by the stronger binding anions.},
  author       = {De Neve, Lorenz and Vermeir, Lien and Sabatino, Paolo and Saveyn, Pieter and Denon, Quenten and Martins, Jos{\'e} and Van Der Meeren, Paul},
  issn         = {0927-7757},
  journal      = {COLLOIDS AND SURFACES A-PHYSICOCHEMICAL AND ENGINEERING ASPECTS},
  keyword      = {Vesicles,Counterion binding,NMR,Cationics,VESICULAR DISPERSIONS,FABRIC SOFTENERS,VESICLES,TRANSITIONS,SULFATE,HALIDES,CHAIN,PH},
  language     = {eng},
  location     = {Rome, Italy},
  pages        = {458--463},
  title        = {Quantification of counterion binding to and its effects on aqueous dispersions of dialkyl cationic surfactants},
  url          = {http://dx.doi.org/10.1016/j.colsurfa.2017.04.031},
  volume       = {532},
  year         = {2017},
}

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