Dynamics of counterions bound to linear micelles in solutions as studied by electric birefringence relaxation and high-frequency dielectric relaxation spectroscopies

Oizumi, Junichi; Kimura, Yasuyuki; Ito, Kohzo; Hayakawa, Ritsuko

doi:10.1016/s0927-7757(98)00675-x

Cited by 4 publications

(3 citation statements)

References 19 publications

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“…10,30,64,65 In the weak electrostatic regime where the majority of counterions are only loosely associated with the charged dendrimer beads, the relevant residence time scale is much shorter; in this regime these counterions can be visualized to perform an oscillatory motion along the direction of loose virtual bonds connecting them with the charged dendrimer beads, in a fashion similar to the motion characterized as the "high frequency" process in dielectric relaxation experiments performed in polyelectrolyte solutions. 32 This process appears to be coupled to global dendrimer motion as well, most probably through the dendrimer rotational relaxation.…”

Section: Summary/conclusionmentioning

confidence: 99%

“…These phases are considered transient rather than permanent with a constant dynamic exchange of counterions between them. 8,11,30,31 Dynamic modes arising from correlated motion of counterions located at a close proximity 10,11,32 to the macroion or even in the diffuse phase 31,33,34 may actually induce conformational changes to the macroion, while collective motion of the more mobile ions can be involved in the formation of charge density waves 10 which may trigger macroion self-assembly.…”

Section: Introductionmentioning

confidence: 99%

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Dynamics of counterions in dendrimer polyelectrolyte solutions

Karatasos

Krystallis

2009

The Journal of Chemical Physics

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Molecular dynamics simulations were employed in models of peripherally charged dendrimers in solutions of explicit solvent and monovalent counterions in order to explore aspects of the dynamic behavior of counterions. The present study explores the effects of varying strength of electrostatic interactions for models of two dendrimer generations, in explicit solvent solutions below the dendrimer overlap concentration. Counterion diffusional motion as well as residence lifetimes of pairs formed by charged dendrimer beads and condensed counterions is monitored in the different electrostatic regimes. Spatiotemporal characteristics of self- and collective counterion motion are explored by means of space-time Van Hove correlation functions. A characteristic scaling law is found to describe the counterion diffusion coefficient as a function of Bjerrum length in the strong electrostatic regime, independent of the size of the dendrimer molecules at the examined volume fractions. The change noted in the diffusional motion of counterions in the range of strong Coulombic interactions is also reflected to their relevant residence times. Development of dynamic heterogeneities in counterion self-motion is observed during the gradual increase in the strength of electrostatic interactions, characterized by the emergence of distinct counterion populations in terms of their mobility. The time scale for the development of such a mobility contrast in the self-motion of the counterions can be correlated with that describing their collective motion as well. The latter increases with Bjerrum length but remains shorter compared to the time scale at which free diffusional motion sets in. Findings from the present study provide further insight on the mechanisms pertinent to ion migration in macroion dispersions and may serve as a basis for the interpretation of ionic motion in a broader range of polyelectrolyte systems.

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Section: Summary/conclusionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Dynamics of counterions in dendrimer polyelectrolyte solutions

Karatasos

Krystallis

2009

The Journal of Chemical Physics

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“…A factor of 5 between the aforementioned timescales should in princi-ple be detectable by dielectric and birefringence experiments probing the high frequency (commonly termed as "HF") ionic motion in polyelectrolyte solutions. 109 In this case, the above description may serve as the basis for the explanation of the origin of possible differences in the ionic transport between systems of different LPE lengths.…”

Section: Dynamic Responsementioning

confidence: 99%

Modeling the formation of ordered nano-assemblies comprised by dendrimers and linear polyelectrolytes: The role of Coulombic interactions

Eleftheriou

Karatasos

2012

The Journal of Chemical Physics

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Models of mixtures of peripherally charged dendrimers with oppositely charged linear polyelectrolytes in the presence of explicit solvent are studied by means of molecular dynamics simulations. Under the influence of varying strength of electrostatic interactions, these systems appear to form dynamically arrested film-like interconnected structures in the polymer-rich phase. Acting like a pseudo-thermodynamic inverse temperature, the increase of the strength of the Coulombic interactions drive the polymeric constituents of the mixture to a gradual dynamic freezing-in. The timescale of the average density fluctuations of the formed complexes initially increases in the weak electrostatic regime reaching a finite limit as the strength of electrostatic interactions grow. Although the models are overall electrically neutral, during this process the dendrimer/linear complexes develop a polar character with an excess charge mainly close to the periphery of the dendrimers. The morphological characteristics of the resulted pattern are found to depend on the size of the polymer chains on account of the distinct conformational features assumed by the complexed linear polyelectrolytes of different length. In addition, the length of the polymer chain appears to affect the dynamics of the counterions, thus affecting the ionic transport properties of the system. It appears, therefore, that the strength of electrostatic interactions together with the length of the linear polyelectrolytes are parameters to which these systems are particularly responsive, offering thus the possibility for a better control of the resulted structure and the electric properties of these soft-colloidal systems.

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Frequency domain electric birefringence study of water-in-oil microemulsion droplets

Shimomura

Ito

2002

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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Dynamics of counterions bound to linear micelles in solutions as studied by electric birefringence relaxation and high-frequency dielectric relaxation spectroscopies

Cited by 4 publications

References 19 publications

Dynamics of counterions in dendrimer polyelectrolyte solutions

Dynamics of counterions in dendrimer polyelectrolyte solutions

Modeling the formation of ordered nano-assemblies comprised by dendrimers and linear polyelectrolytes: The role of Coulombic interactions

Frequency domain electric birefringence study of water-in-oil microemulsion droplets

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