Micellization of amphiphilic block copolymers in binary and ternary solvent mixtures

Sarkar, Biswajit; Ravi, Venkataramanan; Alexandridis, Paschalis

doi:10.1016/j.jcis.2012.09.028

Cited by 60 publications

(38 citation statements)

References 75 publications

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“…For Brij 78, these solutions were in 20% DMSO-d 6 -80% D 2 O (v/v) and for The CMC behavior of various PEO-block copolymers has been investigated in water-ethanol mixed solvents. [33][34][35] These studies have shown that the CMC increased aer addition of ethanol. The addition of DMSO-d 6 to D 2 O seems to show the same tendency, providing better solvent conditions for the Brij 78 and 98 compared to pure D 2 O and disfavoring the formation of micelles (self-assembly).…”

Section: Resultsmentioning

confidence: 99%

Natural product mixture analysis by matrix-assisted DOSY using Brij surfactants in mixed solvents

et al. 2014

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The assignment of NMR signals to specific components in a mixture is a challenging task. Diffusion-Ordered Spectroscopy (DOSY) has provided important progress in this area, allowing the signals originating from individual components of different molecular sizes to be distinguished. However, when the sizes of the compounds are similar and/or the spectra are overlapped, signal assignment can easily become intractable. The use of a co-solute in a matrix-assisted DOSY (MAD) experiment can be a useful solution, improving diffusional (and sometimes spectral) resolution by exploiting selective binding to the matrix.MAD has generated promising results in the study of several types of mixtures, including those of functional and structural isomers. The challenge is to apply MAD to molecules with high structural similarity, for example in natural product mixtures. Various surfactants, including SDS, AOT and CTAB have previously been shown to be effective in MAD analysis. Here we present an important addition, the Brij family of nonionic surfactants. We demonstrate the use of Brij micelles in mixed solvents with a variety of mixtures relevant to natural products.

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Section: Resultsmentioning

confidence: 99%

Natural product mixture analysis by matrix-assisted DOSY using Brij surfactants in mixed solvents

et al. 2014

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“…The self-assembly of surfactants in water is modulated by the presence of co-solutes [16][17][18]. In particular, the addition of cyclodextrins may affect the surfactant association because of their binding interactions with surfactant hydrophobic tails to form inclusion complexes [19].…”

Section: Introductionmentioning

confidence: 99%

Self-assembly of sodium bis(2-ethylhexyl) sulfosuccinate in aqueous solutions: Modulation of micelle structure and interactions by cyclodextrins investigated by small-angle neutron scattering

Fajalia

Antoniou

Alexandridis

et al. 2015

Journal of Molecular Liquids

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Keywords:Sodium dioctyl sulfosuccinate DOSS Aerosol-OT AOT Surfactant Micelle Cyclodextrin Small-angle neutron scattering SANS FormulationThe modulating effects of α-cyclodextrin (α-CD) and hydroxypropyl β-cyclodextrin (HP-β-CD) on micelles formed in water by the double tail surfactant sodium bis(2-ethylhexyl) sulfosuccinate (also known as dioctyl sulfosuccinate (DOSS) or Aerosol-OT (AOT)) have been investigated using small angle neutron scattering (SANS). SANS data were fitted to the core-shell oblate ellipsoid form factor and Hansen-Hayter-based structure factor in order to quantify the effect of cyclodextrins on the micelle structure and inter-micelle interactions. The results suggested that addition of cyclodextrins caused a sharp decrease in surfactant aggregation numbers, micelle dimensions and micelle charge. The micelle shape changed from elongated oblate to sphere upon addition of cyclodextrin at stoichiometric ratio of 1:1 CD:AOT for HP-β-CD and 2:1 for α-CD. HP-β-CD was found more effective than α-CD in influencing the micelle properties. For example, the decrease in surfactant aggregation number upon addition of 1 mM CD at constant total surfactant concentration was about double for HP-β-CD compared to α-CD. The results are consistent with the localization of small amount of cyclodextrins in the micelle, while the remainder stays in the solution pseudophase. The present study offers an improved understanding on the modulating effects of CDs on micelle structure and enables better design of emulsifiers or dispersants in formulations suitable for controlled release of actives.

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“…Mixtures of small molecules surfactant with Pluronic have previously been examined [6,19,20] as has the effect of alcohols [11,13,21]. To our knowledge, there have been far fewer studies of the quaternary systems, Pluronic/small molecule surfactants/alcohol/water, at least in non (micro) emulsion systems.…”

Section: Introductionmentioning

confidence: 99%

Probing competitive interactions in quaternary formulations

Mansour

Cattoz

Heenan

et al. 2015

Journal of Colloid and Interface Science

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Hypothesis: The interaction of amphiphilic block copolymers of the poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) (PEO-PPO-PEO) group with small molecule surfactants may be "tuned" by the presence of selected alcohols, with strong interactions leading to substantial changes in (mixed) micelle morphology, whilst weaker interactions lead to coexisting micelle types. Experiments:The nature and the strength of the interactions between Pluronic P123 (EO20PO70EO20) and small molecule surfactants (anionic sodium dodecylsulfate, SDS, C12SO4Na), (cationic dodecyltrimethylammonium bromide, C12TAB) and (non-ionic polyoxyethylene(23)lauryl ether, Brij 35, C12EO23OH) is expected to depend on the partitioning of the short, medium and long chain alcohols (ethanol, hexanol and decanol respectively) and was probed using tensiometry, pulsed-gradient spin-echo nuclear magnetic resonance (PGSE-NMR) and small-angle neutron scattering (SANS). Findings:The SANS data for aqueous P123 solutions with added alcohols were well described by a charged spherical core/shell model for the micelle morphology. The addition of the surfactants led to significantly smaller, oblate elliptical mixed micelles in the absence of alcohols. Addition of ethanol to these systems led to a decrease in the 2 micelle size, whereas larger micelles were observed upon addition of the longer chain alcohols. NMR studies provided complementary estimates of the micelle composition, and the partitioning of the various components into the micelle.

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Micellization of amphiphilic block copolymers in binary and ternary solvent mixtures

Cited by 60 publications

References 75 publications

Natural product mixture analysis by matrix-assisted DOSY using Brij surfactants in mixed solvents

Natural product mixture analysis by matrix-assisted DOSY using Brij surfactants in mixed solvents

Self-assembly of sodium bis(2-ethylhexyl) sulfosuccinate in aqueous solutions: Modulation of micelle structure and interactions by cyclodextrins investigated by small-angle neutron scattering

Probing competitive interactions in quaternary formulations

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