Dynamics in microemulsions with nonionic surfactant. A combined NMR relaxation and self-diffusion study

Olsson, Ulf; Jonströmer, Mikael; Nagai, Kazunari; Söderman, Olle; Wennerström, Håkan; Klose, G.

doi:10.1007/bfb0114173

Cited by 21 publications

(7 citation statements)

References 24 publications

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“…In the presence of a small amount of water, the PEO blocks become effectively more hydrophilic, and the block copolymers form reverse micelles. A similar behavior is also seen for nonionic surfactants of the ethylene oxide type. , …”

Section: Introductionsupporting

confidence: 69%

A SANS Investigation of Reverse (Water-in-Oil) Micelles of Amphiphilic Block Copolymers

et al. 1999

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Poly(ethylene oxide)−poly(propylene oxide)−poly(ethylene oxide) (PEO−PPO−PEO) block copolymers, commercially available as Poloxamers or Pluronics, are unique in forming ordered cubic phases consisting of reverse (water-in-oil) micelles. We set out to study the microstructure (form and dimension) as the reverse micelles order (from a micellar solution to a cubic lattice) with increasing block copolymer volume fraction and with increasing block copolymer molecular weight. The technique we used was small-angle neutron scattering (SANS) with solvent contrast variation. We selected four block copolymers with known phase behavior in water and p-xylene (Pluronics L44, L64, P84, and P104, all with the same PEO/PPO ratio and molecular formula (EO) x (PO) y (EO) x , where x = 10, 13, 19, 27 and y = 23, 30, 43, 61, respectively) and worked in a dilution line with fixed water to copolymer content (1.2 mol of water per mol of EO). The temperature effect (22 and 45 °C) was also studied. The scattering behavior indicates that the micelles are approximately spherical but polydisperse. We used a two-sphere model where we assumed that all the PEO and the water are in the core of the micelle and that PPO forms a p-xylene-solvated shell. The micellar radius then depends on the molecular weight and the temperature and is approximately constant with concentration. The structure of the reverse micelles is also compared to that of normal (oil-in-water) micelles.

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Section: Introductionsupporting

confidence: 69%

A SANS Investigation of Reverse (Water-in-Oil) Micelles of Amphiphilic Block Copolymers

et al. 1999

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“…It has been reported that up to ≈0.15 water molecules per EO segment are required for EO 13 PO 30 EO 13 to form micelles in o -xylene; similar values have been recently measured for the micellization of a large number of polyoxyalkylene block copolymers in p -xylene . The presence of water is also a prerequisite for the formation of reverse micelles by nonionic alkyl oligooxyethylene surfactants , and for the micellization of poly(oxyethylene)−polystyrene diblock copolymers dissolved in cyclopentane . It appears that PEO needs some water in order to become sufficiently polar and segregated from the hydrophobic block.…”

Section: Phase Behaviormentioning

confidence: 99%

Structural Polymorphism of Amphiphilic Copolymers: Six Lyotropic Liquid Crystalline and Two Solution Phases in a Poly(oxybutylene)-b-poly(oxyethylene)−Water−Xylene System

1997

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Six lyotropic liquid crystalline and two solution (equilibrium) phases can be formed (at 25 °C) by an amphiphilic diblock copolymer composed of poly(ethylene oxide) and poly(butylene oxide) in the presence of water (selective solvent for PEO) and "oil" (p-xylene, a selective solvent for PBO). Oil-in-water ("normal") micellar solution (L1), micellar cubic liquid crystals (I1), hexagonal liquid crystals (H1), and a lamellar structure (LR) are formed with an increase of the copolymer concentration along the oil-lean side of the ternary phase diagram. A micellar solution (L2), micellar cubic liquid crystals (I2), hexagonal liquid crystals (H2), and bicontinuous cubic liquid crystals (V2), all of the water-in-oil ("reverse") morphology, are formed in the water-lean part of the phase diagram with increasing copolymer concentration and in the presence of some water. The oil-in-water [water-in-oil] structures can accommodate up to 0.33 [0.40] g of oil [water]/ g of copolymer. The formation of a reverse micellar cubic phase (I 2), indexed to the crystallographic space group Fd3m (face-centered), is an important feature of this phase diagram as it is one of the first times that such a structure has been identified. The normal micellar cubic structure (I1) is body-centered (Im3m). The microstructure in the bicontinuous cubic region (V2) can be described in terms of a multiply-connected amphiphile bilayer consistent with the Gyroid minimal surface (Ia3d). The absence of a "preferred curvature" in the self-assembly of this macromolecular amphiphile distinguishes it from typical low-molecular weight surfactants and bestows this remarkable structural polymorphism.

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“…Monolaurin/n-Decane System L 3 phase that appears in the water-rich region, the hydrocarbon parts of the surfactant layers are separated (16). Above A mixture of hexaethylene glycol dodecyl ether (C 12 EO 6 ) the L 3 region, a multiphase region including lamellar liquid and monolaurin was used to form highly concentrated emulcrystal (LLC) is formed.…”

Section: Phase Diagram Of Nacl Aqueous Solution/c 12 Eo 6 /mentioning

confidence: 99%

Spontaneous Formation of Highly Concentrated Oil-in-Water Emulsions

Ozawa

Solans

Kunieda

1997

Journal of Colloid and Interface Science

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Dynamics in microemulsions with nonionic surfactant. A combined NMR relaxation and self-diffusion study

Cited by 21 publications

References 24 publications

A SANS Investigation of Reverse (Water-in-Oil) Micelles of Amphiphilic Block Copolymers

A SANS Investigation of Reverse (Water-in-Oil) Micelles of Amphiphilic Block Copolymers

Structural Polymorphism of Amphiphilic Copolymers: Six Lyotropic Liquid Crystalline and Two Solution Phases in a Poly(oxybutylene)-b-poly(oxyethylene)−Water−Xylene System

Spontaneous Formation of Highly Concentrated Oil-in-Water Emulsions

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