Soft Interaction between Dissolved Flexible Dendrimers:  Theory and Experiment

Likos, Christos N.; Schmidt, Matthias; Löwen, Hartmut; Ballauff, Matthias; Pötschke, D.; Lindner, Peter

doi:10.1021/ma001346x

Cited by 109 publications

(130 citation statements)

References 33 publications

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“…Both star polymers and flexible dendrimers fall into this fuzzy category, yet they may be highly aspherical. Likos et al [66] have also shown that stars and flexible dendrimers have the same kind of soft pair potentials. We thus expect such considerations of interfacial-area minimization to become highly relevant in the upcoming study of soft quasicrystals.…”

Section: Free-energy Functionals and Stability Analysismentioning

confidence: 94%

“…Block copolymers, like homopolymers, can be linear or branched. Two branched architectures which can be well controlled, and thus have been drawing considerable attention recently, are star polymers [52][53][54][55][56][57][58][59][60][61][62], where the chains are joined in one point, and dendrimers [60,[63][64][65][66], having a tree-like structure.…”

Section: Quasicrystals-terminology and General Frameworkmentioning

confidence: 99%

See 1 more Smart Citation

Soft quasicrystals–Why are they stable?

Lifshitz

Diamant

2007

Philosophical Magazine

105

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In the last two years we have witnessed the exciting experimental discovery of soft matter with nontrivial quasiperiodic long-range order-a new form of matter termed a soft quasicrystal. Two groups have independently discovered such order in soft matter: Zeng et al. [Nature 428 (2004) 157] in a system of dendrimer liquid crystals; and Takano et al. [J. Polym. Sci. Polym. Phys. 43 (2005) 2427] in a system of ABC star-shaped polymers. These newly discovered soft quasicrystals not only provide exciting platforms for the fundamental study of both quasicrystals and of soft matter, but also hold the promise for new applications based on self-assembled nanomaterials with unique physical properties that take advantage of the quasiperiodicity, such as complete and isotropic photonic band-gap materials. Here we provide a concise review of the emerging field of soft quasicrystals, suggesting that the existence of two natural length-scales, along with 3-body interactions, may constitute the underlying source of their stability. BackgroundThe discovery of quasicrystals by Shechtman more than two decades ago We know today that quasicrystals are more common than one had originally expected. Scores of binary and ternary metallic alloys are known to form quasicrystalline phases [22]-mostly with icosahedral or decagonal point-group symmetry-and more are being discovered all the time. Nevertheless, it is only in the last couple of years that quasicrystals have been discovered (independently) in two 1

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Section: Free-energy Functionals and Stability Analysismentioning

confidence: 94%

Section: Quasicrystals-terminology and General Frameworkmentioning

confidence: 99%

Soft quasicrystals–Why are they stable?

Lifshitz

Diamant

2007

Philosophical Magazine

105

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“…Dendrimers. By employing a simple, mean-field theory based on the measured monomer density profiles of fourth-generation dendrimers, a Gaussian function of the form (2) has been shown to accurately describe the effective interaction between the centres of mass of these dendrimers [19,20]. The prefactor ε has in this case a higher value then for linear polymers, ε ∼ = 10 k B T .…”

Section: Effective Interactions Between Polymeric Macromoleculesmentioning

confidence: 99%

Exotic fluids and crystals of soft polymeric colloids

Likos

Hoffmann

Löwen

et al. 2002

J. Phys.: Condens. Matter

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Abstract. We discuss recent developments and present new findings in the colloidal description of soft polymeric macromolecular aggregates. For various macromolecular architectures, such as linear chains, star polymers, dendrimers and polyelectrolyte stars, the effective interactions between suitably chosen coordinates are shown to be ultrasoft, i.e., they either remain finite or diverge very slowly at zero separation. As a consequence, the fluid phases have unusual characteristics, including anomalous pair correlations and mean-field like thermodynamic behaviour. The solid phases can exhibit exotic, strongly anisotropic as well as open crystal structures. For example, the diamond and the A15-phase are shown to be stable at sufficiently high concentrations. Reentrant melting and clustering transitions are additional features displayed by such systems, resulting in phase diagrams with a very rich topology. We emphasise that many of these effects are fundamentally different from the usual archetypal hard sphere paradigm. Instead, we propose that these fluids fall into the class of mean-field fluids.

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“…Before discussing the ramifications of these properties on the thermodynamics of the star polymer fluid, we point out that recently quite a bit of attention has been focussed on a related but distinct class of fluids, namely the ones whose constituent particles interact by means of positive-definite, purely repulsive potentials that do not diverge at the origin [104][105][106][107][108][109][110]. It was shown that for such systems, a 'meanfield limit' is satisfied [109]: at sufficiently high densities for all temperatures and at sufficiently high temperatures for all densities, the direct correlation function c(r) of the fluid [71] is approximated extremely well by its large-r asymptotic behavior, c(r) ∼ −βv(r) at all r. Hence, for bounded potentials and under the condition of high densities and/or temperatures, we can write at all separations and for all densities:…”

Section: The Mean-field Character Of the Star Polymer Fluidmentioning

confidence: 99%

Star Polymers: From Conformations to Interactions to Phase Diagrams

Likos¹,

Harreis²

2002

Condens. Matter Phys.

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We review recent progress achieved in the theoretical description of the interactions, correlations, and phase behavior of concentrated solutions of star polymers, sterically stabilized colloids, and micelles. We show that the theoretical prediction of an ultrasoft, logarithmically diverging effective interaction between the star centers, which has been confirmed by SANSexperiments and computer simulations, lies in the core of a host of unusual phenomena encountered in such systems. These include anomalous structure factors, reentrant melting behavior, as well as a variety of exotic crystal phases. Extensions to polydisperse stars and the role of many-body forces are also discussed. A particular 'mean-field' character of star polymer fluids is presented and it is shown that it manifests itself in the shape and structure of sedimentation profiles of these systems.

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Soft Interaction between Dissolved Flexible Dendrimers: Theory and Experiment

Cited by 109 publications

References 33 publications

Soft quasicrystals–Why are they stable?

Soft quasicrystals–Why are they stable?

Exotic fluids and crystals of soft polymeric colloids

Star Polymers: From Conformations to Interactions to Phase Diagrams

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