Magnetic Control over Liquid Surface Properties with Responsive Surfactants

Brown, Paul; Bushmelev, Alexey; Butts, Craig P.; Cheng, Jing; Eastoe, Julian; Grillo, Isabelle; Heenan, Richard K.; Schmidt, Annette

doi:10.1002/anie.201108010

Cited by 205 publications

(257 citation statements)

References 27 publications

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“…In that context it might also be mentioned that ''magnetic surfactants'' have received high attention very recently. 28 Accordingly, self-assembly in MRTIL is an interesting question and in this work we describe the formulation of a magnetic microemulsion based on a MRTIL, which to the best of our knowledge, is the first time that such a system is described. Other microemulsions with magnetic properties are all based on microemulsions containing magnetic inorganic nanoparticles, which is a very different type of formulation.…”

Section: Introductionmentioning

confidence: 99%

Magnetic microemulsions based on magnetic ionic liquids

Klee

Prévost

Kunz

et al. 2012

Phys. Chem. Chem. Phys.

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Microemulsions with magnetic properties were formed by employing a magnetic room temperature ionic liquid (MRTIL) as polar phase, cyclohexane as oil, and an appropriate mixture of ionic surfactant and decanol as a cosurfactant. By means of small-angle neutron scattering (SANS) and electric conductivity the microemulsion structure could be confirmed, where the classical structural sequence of oil-continuous-bicontinuous-polar phase continuous is observed with increasing ratio [polar phase]/ [oil]. Accordingly a maximum of the structural size is observed at about equal volumes of oil and MRTIL contained. Therefore this system is structurally the same as normal microemulsions but with the magnetic properties added to it by the incorporation into the systems formulation.

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Section: Introductionmentioning

confidence: 99%

Magnetic microemulsions based on magnetic ionic liquids

Klee

Prévost

Kunz

et al. 2012

Phys. Chem. Chem. Phys.

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“…1 These magneto-responsive surfactants are based on common cationic surfactants with metal complex anions, which, because they contain high effective concentrations of metal centres, allow physico-chemical properties to be controlled non-invasively and reversibly by external magnetic fields. Surprisingly, even dilute micellar solutions of these paramagnetic surfactants exhibit a magnetic response, opening up new possibilities for control over interfaces, dispersions, colloids and nanoparticles.…”

Section: Introductionmentioning

confidence: 99%

Properties of New Magnetic Surfactants

Brown¹,

Bushmelev

Butts³

et al. 2013

Langmuir

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105

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This paper describes the synthesis and detailed characterization of a new set of magnetic surfactants containing lanthanide metal counterions. SQUID magnetometry has been used to elucidate the magnetic phase behaviour, and small-angle neutron scattering (SANS) provides evidence of micellar aggregation in aqueous media. This study also reveals that for cationic surfactants in aqueous systems there appears to be no significant increase in magnetic susceptibility after micellization.

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“…[8] In 2014, Degen et al investigated organic surfactants with paramagnetic FeCl 4 À as acounterion and concluded that there is no special "magnetic surfactant effect".…”

mentioning

confidence: 99%

“…[8] In 2014, Degen et al investigated organic surfactants with paramagnetic FeCl 4 À as acounterion and concluded that there is no special "magnetic surfactant effect". [9] This last study motivated us to invest effort in preparing compounds in which the transition-metal species is an integral part of the head group.…”

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confidence: 99%

Magneto‐Adaptive Surfactants Showing Anti‐Curie Behavior and Tunable Surface Tension as Porogens for Mesoporous Particles with 12‐Fold Symmetry

et al. 2017

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Gaining external control over self-organization is of vital importance for future smart materials.S urfactants are extremely valuable for the synthesis of diverse nanomaterials. Their self-assembly is dictated by microphase separation, the hydrophobic effect, and head-group repulsion. It is desirable to supplement surfactants with an added mode of long-range and directional interaction. Magnetic forces are ideal, as they are not shielded in water.W er eport on surfactants with heads containing tightly bound transition-metal centers.T he magnetic moment of the head was varied systematically while keeping shape and charge constant. Changes in the magnetic moment of the head led to notable differences in surface tension, aggregate size, and contact angle,which could also be altered by an external magnetic field. The most astonishing result was that the use of magnetic surfactants as structuredirecting agents enabled the formation of porous solids with 12-fold rotational symmetry.The spontaneous formation of organized patterns as an intrinsic property of asystem containing discrete constituents, ap rocess termed self-assembly,h as fascinated scientists for decades.N ature shows the enormous potential of such behavior, since many of the unexcelled properties of biological matter originate from its capacity for adaptive selfassembly.[1] Full exploration of this potential in materials science is still remote,a smost reported examples of selfassembly so far are dictated by internal factors,s uch as thermodynamic equilibrium.[2] Systems reaching as tate of higher order only under constant consumption of energy (dissipative,n on-equilibrium state) have seldom been reported.[3] Apremise for advancing research in this direction is that compounds capable of adaptive self-assembly can be equipped with the ability to be actuated externally.Examples from particle research, such as dispersions of superparamagnetic colloids, [4] demonstrate the promise of manipulation by the use of magnetism, because it can be applied in astatic or dynamic way,a nd unlike electric fields,m agnetism is not damped in aqueous electrolytes.T hus,i ti sw orth exploring the use of external magnetic fields to trigger the selforganization of molecular systems.As model systems for the self-assembly of soft matter, surfactants are the focus of much current interest. Surfactants are molecular species that contain two moieties of opposite solvent compatibility arranged in adipolar geometry.Inpolar solvents,u sually water, concentration-dependents elf-organization takes place.T he amphiphilic properties of surfactants make them suitable for the stabilization of interfaces of many kinds,f or example,f or the generation of nanoparticles or nanoporous materials.[5] Thetypical head group of surfactants is organic in nature and, thus,d iamagnetic.T om ake as urfactant magnetic, one of its constituents should contain ap aramagnetic metal species.T his emerging field was reviewed very recently by Eastoe and co-workers.[6] Most known examples involve surfac...

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Magnetic Control over Liquid Surface Properties with Responsive Surfactants

Cited by 205 publications

References 27 publications

Magnetic microemulsions based on magnetic ionic liquids

Magnetic microemulsions based on magnetic ionic liquids

Properties of New Magnetic Surfactants

Magneto‐Adaptive Surfactants Showing Anti‐Curie Behavior and Tunable Surface Tension as Porogens for Mesoporous Particles with 12‐Fold Symmetry

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