Starlike Micelles with Starlike Interactions: A Quantitative Evaluation of Structure Factors and Phase Diagram

Laurati, Marco; Stellbrink, Jörg; Lund, Reidar; Willner, Lutz; Richter, D.; Zaccarelli, Emanuela

doi:10.1103/physrevlett.94.195504

Cited by 70 publications

(98 citation statements)

References 24 publications

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“…17 In this paper, we will study the dynamics of a solution of high-functionality ( f = 128 arm) star polymers by tracking the motion of the centres-of-mass of each star polymer. Each pair of particles i and j at distance r ij interacts through an equilibrium interaction potential V ss (r ij ), which has been derived in the past 18,19 and whose validity has been confirmed through comparison with scattering data 18,20 and computer simulations. 21 It reads as…”

Section: Tests a Test System: Star Polymer Solutionmentioning

confidence: 97%

Momentum conserving Brownian dynamics propagator for complex soft matter fluids

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Briels

2014

The Journal of Chemical Physics

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A Brownian dynamics study on the self-diffusion of charged tracers in dilute polyelectrolyte solutions J. Chem. Phys. 122, 124905 (2005) We present a Galilean invariant, momentum conserving first order Brownian dynamics scheme for coarse-grained simulations of highly frictional soft matter systems. Friction forces are taken to be with respect to moving background material. The motion of the background material is described by locally averaged velocities in the neighborhood of the dissolved coarse coordinates. The velocity variables are updated by a momentum conserving scheme. The properties of the stochastic updates are derived through the Chapman-Kolmogorov and Fokker-Planck equations for the evolution of the probability distribution of coarse-grained position and velocity variables, by requiring the equilibrium distribution to be a stationary solution. We test our new scheme on concentrated star polymer solutions and find that the transverse current and velocity time auto-correlation functions behave as expected from hydrodynamics. In particular, the velocity auto-correlation functions display a long time tail in complete agreement with hydrodynamics. C 2014 AIP Publishing LLC. [http://dx

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Section: Tests a Test System: Star Polymer Solutionmentioning

confidence: 97%

Momentum conserving Brownian dynamics propagator for complex soft matter fluids

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Briels

2014

The Journal of Chemical Physics

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“…The contribution V ss corresponds to the equilibrium interaction potential (the potential of mean force), which has been derived in the past (Likos et al 1998;Witten and Pincus 1986), and whose validity has been confirmed through comparison with scattering data (Laurati et al 2005;Likos et al 1998) and computer simulations (Jusufi et al 1999). It reads as…”

Section: Potential Of Mean Force Between Star Polymersmentioning

confidence: 99%

Computer simulation of the rheology of concentrated star polymer suspensions

et al. 2009

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We use particle-based computer simulations to study the rheology of suspensions of highfunctionality star polymers with long entangled arms. Such particles have properties which are intermediate between those of soft colloidal particles and entangled polymer chains. In the simulations, each star polymer is coarse-grained to a single particle. In order to faithfully reproduce dynamical properties, it is very important to not only include time-averaged interactions (potentials of mean force) but to also account for transient interactions induced by entanglements between the arms of different star polymers. Using a model which has all these features, it is found that, for sufficiently high shear rates, the start-up shear stress displays an overshoot. With increasing concentration, the core interactions increasingly dominate the initial stress response, leading to a maximum in the stress overshoot at relatively low strain values (0.1 to 0.5). Transient forces start to dominate after this initial stage. In a simulated experi- ment in which the shear rate is suddenly stepped-down from a high to a lower value, the stress shows a clear undershoot, with the minimum stress again at a relatively low strain value (based on the new shear rate). Finally, it is shown that a stress plateau develops in the flow curve. This plateau is absent when the transient forces between the polymer stars are not taken into account.

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“…Building on these simple models, great advances have been made in the study of gel and glass formation in colloidal systems [3,4]. More recently, the interest of colloid scientists has shifted towards the study of soft particles, among which star polymers have emerged as a model for a wide class of soft spheres, including blockcopolymer micelles [5,6] and microgel particles [7,8]. For a star polymer, softness can be controlled by varying its number of arms (or functionality f), allowing to bridge the gap between linear polymer chains (f ¼ 2) and hard spheres (f !…”

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confidence: 99%

“…On the other hand, the paradigmatic case of a mixture of star polymers and linear chains (the direct soft counterpart of the AO model) has been investigated theoretically [14,16] and experimentally by (mainly) macroscopic rheology [11,12,17]; however, detailed structural information is still missing. Recently a microscopic theory [14,16], capable to appropriately coarse-grain stars and chains, has been developed, but an accurate comparison between theoretical predictions and experimental results for the structural correlations for starchains mixtures has not been attempted so far.Recently, we introduced kinetically frozen starlike micelles [6,18] formed by the amphiphilic block copolymer poly(ethylene-alt-propylene)-poly(ethylene oxide), PEP-PEO, as a tunable model system for ultrasoft colloids [9]. In this Letter we study mixtures of starlike micelles and linear (PEO) chains and provide a systematic and quantitative characterization of structure factors and phase behavior in terms of effective interactions.…”

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confidence: 99%

Ultrasoft Colloid-Polymer Mixtures: Structure and Phase Diagram

et al. 2011

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Binary mixtures of ultrasoft colloids and linear polymer chains were investigated by small-angle neutron scattering and liquid state theory. We show that experimental data can be described by employing recently developed effective interactions between the colloid and the polymer chains, in which both components are modeled as point particles in a coarse-grained approach, in which the monomers have been traced out. Quantitative, parameter-free agreement between experiment and theory for the pair correlations, the phase behavior and the concentration dependence of the interaction length is achieved. DOI: 10.1103/PhysRevLett.106.228301 PACS numbers: 82.70.Ày, 61.20.Gy, 64.70.km, 82.70.Dd Hard spheres have been established in the past as model systems to investigate on a fundamental level the effective interactions and phase behavior of soft matter [1]. Following in complexity, colloid-polymer mixtures are usually described by the Asakura-Oosawa (AO) model [2]. Building on these simple models, great advances have been made in the study of gel and glass formation in colloidal systems [3,4]. More recently, the interest of colloid scientists has shifted towards the study of soft particles, among which star polymers have emerged as a model for a wide class of soft spheres, including blockcopolymer micelles [5,6] and microgel particles [7,8]. For a star polymer, softness can be controlled by varying its number of arms (or functionality f), allowing to bridge the gap between linear polymer chains (f ¼ 2) and hard spheres (f ! 1) [9]. Therefore, star polymers feature tunable softness, which is responsible for the observation of anomalous structural behavior [9] and for the formation of several crystal structures [5,10]. Mixtures of soft particles offer a much higher versatility with respect to their hard counterparts, both in terms of structural and rheological properties [11][12][13] and of effective interactions [14]. In particular, mixtures of star polymers of different sizes and functionalities have been recently investigated in a joint theoretical and experimental effort, revealing the existence of multiple glassy states [15]. On the other hand, the paradigmatic case of a mixture of star polymers and linear chains (the direct soft counterpart of the AO model) has been investigated theoretically [14,16] and experimentally by (mainly) macroscopic rheology [11,12,17]; however, detailed structural information is still missing. Recently a microscopic theory [14,16], capable to appropriately coarse-grain stars and chains, has been developed, but an accurate comparison between theoretical predictions and experimental results for the structural correlations for starchains mixtures has not been attempted so far.Recently, we introduced kinetically frozen starlike micelles [6,18] formed by the amphiphilic block copolymer poly(ethylene-alt-propylene)-poly(ethylene oxide), PEP-PEO, as a tunable model system for ultrasoft colloids [9]. In this Letter we study mixtures of starlike micelles and linear (PEO) chains and provide a s...

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Starlike Micelles with Starlike Interactions: A Quantitative Evaluation of Structure Factors and Phase Diagram

Cited by 70 publications

References 24 publications

Momentum conserving Brownian dynamics propagator for complex soft matter fluids

Momentum conserving Brownian dynamics propagator for complex soft matter fluids

Computer simulation of the rheology of concentrated star polymer suspensions

Ultrasoft Colloid-Polymer Mixtures: Structure and Phase Diagram

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