Morphology and viscoelasticity of bilayer aqueous colloids of low-molecular and macromolecular amphiphiles

Matsumoto, Takayoshi; Heiuchi, T.; Horie, Keita

doi:10.1007/bf01410151

Cited by 22 publications

(15 citation statements)

References 19 publications

(17 reference statements)

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“…We have used a cationic double-chain surfactant, didodecyldimethylammonium bromide, or DDAB, which has been studied for over 30 years, for its ability to form various bilayer structures. − The high surfactant packing parameter (∼0.62), which is the ratio of the surfactant tail volume to the product of the headgroup area and the chain length, causes the double-chain DDAB molecules to form vesicles or lamellar particles when the concentration is above its critical vesicle concentration of 6.5 × 10 –4 wt % . The liquid-crystalline and bilayer chain melting phase-transition temperature ( T m ) is about 16 °C, causing the bilayer interior to be fluid and the vesicles to be deformable.…”

Section: Experimental Results and Discussionmentioning

confidence: 99%

“…11−13 The high surfactant packing parameter (∼0.62), which is the ratio of the surfactant tail volume to the product of the headgroup area and the chain length, 1 causes the double-chain DDAB molecules to form vesicles or lamellar particles when the concentration is above its critical vesicle concentration of 6.5 × 10 −4 wt %. 14 The liquid-crystalline and bilayer chain melting phase-transition temperature (T m ) is about 16 °C, causing the bilayer interior to be fluid and the vesicles to be deformable. At 25 °C, these vesicles can be stable for months.…”

Section: Resultsmentioning

confidence: 99%

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Use of Close-Packed Vesicular Dispersions to Stabilize Colloidal Particle Dispersions against Sedimentation

2015

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For many applications of colloidal dispersions, the particles must be suspended for a long time. This is often accomplished by preventing agglomeration, which generates aggregates of increasing size. Nevertheless, many colloidal dispersions of dense particles may settle even without agglomeration. Preventing sedimentation without significantly increasing the bulk dispersion viscosity is difficult and has received little attention in the literature. However, settling can be drastically reduced through the novel use of close-packed vesicular dispersions at high enough concentrations, which are non-Newtonian shear-thinning fluids. Such dispersions have much higher viscosities at the low shear stresses "felt" by sedimenting colloidal particles than at the high shear stresses relevant to bulk dispersion flow. In a practical example, dense TiO 2 nanoparticles which normally would settle rapidly can remain suspended for at least 6 months without any observable sedimentation when they are introduced into a close-packed vesicular dispersion, while the dispersion retains its flowability. Cryo-TEM images reveal that the vesicles in these dispersions are tightly close-packed. Dynamic light scattering and electrophoretic mobility data also confirm that the vesicles in such dispersions have very low mobilities.

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Section: Experimental Results and Discussionmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Use of Close-Packed Vesicular Dispersions to Stabilize Colloidal Particle Dispersions against Sedimentation

2015

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“…The system of 1 wt~ shows Newtonian flow and the viscosity is about 0.1 poise, which is approximately 10-times higher than that of pure water. It was confirmed with a polarized microscope that optical anisotropic spherical particles are dispersed in the isotropic matrix [16]. Both G' and G" increase markedly in concentrations above 2 wt0/0 and become almost flat against the frequency axis.…”

Section: " Imentioning

confidence: 62%

“…It may be considered that the bilayer structure can develop most fully in this concentration range. The morphology of the bilayer structure of the DMA system has been reported elsewhere in detail [16]. Figure 2 shows flow curves of the aqueous colloidal system of egg lecithin EL.…”

Section: " Imentioning

confidence: 99%

Interaction between amphiphiles and water molecules in concentrated bilayer aqueous colloids

Matsumoto

Ito

Kohno

1989

Colloid & Polymer Sci

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Interaction between amphiphiles and water molecules in micelle or bilayer structure has been investigated using aqueous colloids of various amphiphiles through the rheological data and the spin-lattice relaxation time T 1 of the proton of water molecule. T1 of the water proton has been measured by the inversion recovery method and determined as a single exponential relaxation process.The chemical shift of the water proton is almost independent of the amphiphilic concentration; however, it shifts toward a higher magnetic field with increasing temperature in a way similar to that in pure water and in the amphiphilic aqueous systems. These facts mean that there is no significant difference in the magnetic field environment of the water protons in these systems.The water molecule is not necessarily bound in the fully developed micelle or bilayer (rod-like or lamella) structure which induces the high viscosity or high rigidity of the colloidal system. On the other hand, the water molecule is bound in the micelle colloids of amphoteric amphiphiles or amphiphiles whose molecular assembly creates a relatively strong electrostatic field. The activation entropy of the bound water is negative and this suggests that water molecules assume some ordered structure in the bound state.

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“…We recently presented a novel method of using close-packed fluid vesicular dispersions for making stable suspensions of dense titania particles in water with Δρ = 3.2 g/cm 3 and d = 280 ± 100 nm. , Many double-chain surfactants form lamellar liquid crystals, multilamellar vesicles, or “liposomes”, and unilamellar vesicles, or simply “vesicles”. − A vesicle is a hollow surfactant-based particle in which a thin layer (usually a bilayer) of surfactant contains and completely surrounds an aqueous core.…”

Section: Introductionmentioning

confidence: 99%

Effects of Light Dispersed Particles on the Stability of Dense Suspended Particles Against Sedimentation

2019

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A novel method in which vesicular dispersions of the double-chain cationic surfactant DDAB (didodecyldimethylammonium bromide) stabilize suspensions of high density titania particles was recently presented (Yang, Y.-J; Corti, D.S.; Franses, E. I. Langmuir 2015, 31, 8802–8808). At high enough DDAB concentration, the vesicles form a close-packed structure, providing strong resistance to the sedimentation of the titania particles, while the dispersions remain highly shear-thinning with moderate limiting viscosities. Here, to elucidate the key factors of the mechanism by which vesicles or other nonsettling particles stabilize high density particles against sedimentation, we use Brownian dynamics simulations (BDS) to examine the sedimentation behavior of mixtures of “dense particles” that settle rapidly on their own and “light particles” that represent nonsettling “rigid vesicles”. BDS confirm that for large enough values of the volume fraction ϕ2 of the light particles, the dense particles should remain suspended. The rheological behavior of the mixtures is also computed with BDS. The observed shear-thinning behavior of the light particle dispersion suggests that the suspensions of the dense particles are still flowable at high shear stresses. Furthermore, the local viscosity of light particles around the dense particles significantly increases with increasing ϕ2, particularly when the same gravitational force applied in the BDS is exerted on a dense particle. The arrangement of light particles around the moving dense particles is an important factor in determining the stability of the dense particles against sedimentation. The BDS results indicate that dispersions of nonsettling particles provide a general method for the stabilization against sedimentation of high density particles.

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Morphology and viscoelasticity of bilayer aqueous colloids of low-molecular and macromolecular amphiphiles

Cited by 22 publications

References 19 publications

Use of Close-Packed Vesicular Dispersions to Stabilize Colloidal Particle Dispersions against Sedimentation

Use of Close-Packed Vesicular Dispersions to Stabilize Colloidal Particle Dispersions against Sedimentation

Interaction between amphiphiles and water molecules in concentrated bilayer aqueous colloids

Effects of Light Dispersed Particles on the Stability of Dense Suspended Particles Against Sedimentation

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