Bridging of an Isolated Polymer Chain

Jimenez, Jorge; Joannis, Jason de; Bitsanis, Ioannis A.; Rajagopalan, Raj

doi:10.1021/ma000564n

Cited by 19 publications

(31 citation statements)

References 32 publications

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“…Nevertheless, partial crystallization and amorphous-crystal 49,50 This observation agrees with Pusey's experiments which show that solutions with size dispersity higher than 7.5% freeze partially, while those with size dispersity around 12% do not. DFT studies 51,52 that refer to a terminal size dispersity of around 5%-7% are also in agreement with our results, considering the fact that in these studies the constrained eutectic model, 52 which does not allow fractionization, was employed.…”

Section: Resultssupporting

confidence: 89%

Phase equilibrium of colloidal suspensions with particle size dispersity: A Monte Carlo study

Yiannourakou

Economou

Bitsanis

2009

The Journal of Chemical Physics

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We have studied the crystalline-amorphous coexistence for systems of polydisperse soft spheres that interact via a purely repulsive power law potential. Potential softness quantified by the exponent of the potential was a primary input in our simulations. Simulations were performed in the isobaric semigrand statistical ensemble, i.e., the composition of the parent distribution was not fixed in our systems. Gibbs-Duhem integration was used to trace the coexistence pressure as a function of potential softness for monodisperse systems. A second Gibbs-Duhem integration, initiated from the monodisperse coexistence curve, was employed to determine coexistence pressure versus imposed variance of the activity distribution. Amorphous-crystalline coexistence densities and volume fractions were determined to be monotonically increasing functions of the breadth of particle size dispersity. Semigrand ensemble simulations testified to the existence of a terminal diameter dispersity, i.e., a dispersity above which no amorphous-crystalline phase coexistence was observed. At the terminus size dispersity increases from 5.8% to 6.1% to 6.4% and to 6.7% and 6.5% for the crystalline phase as the steepness parameter n, takes on smaller values: from 100 to 50 to 12 to 10 and 8, respectively. In sharp contrast to the crystalline phases' enhanced, by potential softness, allowable size dispersity the amorphous phase exhibits an opposite trend, as potential interactions soften. Furthermore, amorphous phases accommodate, on average, smaller particles than those of the ordered (fcc) phase. Contrary to widely accepted intuition crystalline phases composed of size-disperse particulates exhibit a higher degree of local order than their monodisperse counterparts, admittedly at differing thermodynamic conditions.

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Section: Resultssupporting

confidence: 89%

Phase equilibrium of colloidal suspensions with particle size dispersity: A Monte Carlo study

Yiannourakou

Economou

Bitsanis

2009

The Journal of Chemical Physics

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“…The bridging was extensively studied experimentally [6][7][8], theoretically [9][10][11] and by Monte Carlo simulations [12][13][14][15][16]. It was exploited practically for water purification by adding high molecular weight polyacrylamides to flocculate the small particles suspended in water [17].…”

Section: Introductionmentioning

confidence: 99%

The bridging force between two plates by polyelectrolyte chains

Huang

Ruckenstein

2004

Advances in Colloid and Interface Science

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“…The solid line in the figure corresponds to the estimation based on the number and size distribution of the bridges. 27,43 The deviation between the two curves indicates the onset of the steric repulsion between the layers. (A similar behavior is observed in our work on bridging by a single chain for low adsorption energies, i.e., e 0.5 k B T.) The fact that f br obtained directly from simulations is approximately constant as Γ f 0 indicates that for very low coverages the surface can be considered as a collection of isolated polymer chains.…”

Section: Bridging In Undersaturated Layersmentioning

confidence: 99%

“…One of our objectives is to complement the study of bridging due to isolated polymer chains we had initiated earlier. 27 In addition, we wish to examine the competition between bridging attraction and steric repulsion that occurs between undersaturated polymer layers. We also provide a detailed comparison between the simulation results and the numerical mean-field predictions based on first-order (standard SF theory) and secondorder Markov chains (hereinafter referred to as SF 1 and SF 2 , respectively).…”

Section: Introductionmentioning

confidence: 99%

Interaction between Undersaturated Polymer Layers: Computer Simulations and Numerical Mean-Field Calculations

et al. 2000

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Lattice Monte Carlo simulations and the contact distribution method are used to analyze the force of interactions between two undersaturated polymer layers in good solvents. The net force between the surfaces, resulting from a competition between bridging attraction and steric repulsion, is obtained unambiguously for coverages Γ ranging from 0 to the saturation coverage Γ0. The sizes and the number of the bridges are in qualitative agreement with previous scaling analysis, but a number of quantitative differences important in practice emerge from the simulations. While the bridges may be considered as independent elastic tethers at low coverages, steric interactions begin to exert influence for coverages as low as Γ ≈ 0.3Γ 0. Comparison of the results of the simulations with numerical meanfield calculations based on second-order Markov chains (i.e., without backfolding) shows good agreement with some of the structural features of the polymer layer, but important discrepancies regarding the force of interaction exist for all values of Γ/Γ0. Whereas the mean-field calculations predict that the crossover from attraction to steric repulsion occurs only near saturation, the simulations show the crossover to occur at a much higher degree of undersaturation (i.e., Γ/Γ0 ≈ 0.85). The simulation method used provides an opportunity to scrutinize systematically the details of the mean-field theory and to refine the theory for providing better guidance in practice. The results presented here focus on a low molecular weight chain (N ) 200). Whether the asymptotic behavior for very long chains predicted by the scaling/ free energy functional approach is obtained still needs to be tested.

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Bridging of an Isolated Polymer Chain

Cited by 19 publications

References 32 publications

Phase equilibrium of colloidal suspensions with particle size dispersity: A Monte Carlo study

Phase equilibrium of colloidal suspensions with particle size dispersity: A Monte Carlo study

The bridging force between two plates by polyelectrolyte chains

Interaction between Undersaturated Polymer Layers: Computer Simulations and Numerical Mean-Field Calculations

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