A new double-rebridging technique for linear polyethylene

Banaszak, Brian J.; Pablo, Juan J. de

doi:10.1063/1.1583673

Cited by 56 publications

(52 citation statements)

References 36 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…All results presented below are in LJ units reduced by the properties of the polymer monomers (e.g., T = T* k B /ε, where T* is the temperature in laboratory units), and all of our calculations were performed using the LAMMPS simulation package. 25 We begin by carefully equilibrating our systems at a temperature that is well above the glass transition temperature (T = 1.5) using a combination of connectivity-altering Monte Carlo moves [26][27][28] and molecular dynamics (MD) in the NPT ensemble. Equilibration was justified by ensuring that the monomers had diffused multiple times the average end-to-end distance, R E , and by requiring that the statistics of the entanglement network no longer changed with further equilibration.…”

Section: Methodsmentioning

confidence: 99%

Evolution of collective motion in a model glass-forming liquid during physical aging

Shavit

Douglas

Riggleman

2013

The Journal of Chemical Physics

View full text Add to dashboard Cite

At temperatures moderately below their glass transition temperature, the properties of many glassforming materials can evolve slowly with time in a process known as physical aging whereby the thermodynamic, mechanical, and dynamic properties all drift towards their equilibrium values. In this work, we study the evolution of the thermodynamic and dynamic properties during physical aging for a model polymer glass. Specifically, we test the relationship between an estimate of the size of the cooperative rearrangements taking the form of strings and the effective structural relaxation time predicted by the Adam-Gibbs relationship for both an equilibrium supercooled liquid and the same fluid undergoing physical aging towards equilibrium after a series of temperature jumps. We find that there is apparently a close correlation between a structural feature of the fluid, the size of the string-like rearrangements, and the structural relaxation time, although the relationship for the aging fluid appears to be distinct from that of the fluid at equilibrium.

show abstract

Section: Methodsmentioning

confidence: 99%

Evolution of collective motion in a model glass-forming liquid during physical aging

Shavit

Douglas

Riggleman

2013

The Journal of Chemical Physics

View full text Add to dashboard Cite

show abstract

“…The frequency should not be too large to avoid The efficiency of DB moves is commonly characterized in terms of the relaxation time τ ee of the end-to-end vector correlation function [30,31]. For normal chain dynamics this would indeed characterize the longest relaxation time of the system, i.e.…”

Section: B Perturbation Calculationmentioning

confidence: 99%

“…For N = 8192 this corresponds to 3 · 10 7 MCS. This allows us even for the largest chain lengths to observe monomer diffusion over several R e within the 10 8 MCS which are feasible on our XEON-PC processor cluster.The efficiency of DB moves is commonly characterized in terms of the relaxation time τ ee of the end-to-end vector correlation function [30,31]. For normal chain dynamics this would indeed characterize the longest relaxation time of the system, i.e.…”

mentioning

confidence: 99%

Intramolecular long-range correlations in polymer melts: The segmental size distribution and its moments

et al. 2007

View full text Add to dashboard Cite

Presenting theoretical arguments and numerical results we demonstrate long-range intrachain correlations in concentrated solutions and melts of long flexible polymers which cause a systematic swelling of short chain segments. They can be traced back to the incompressibility of the melt leading to an effective repulsion u(s) ≈ s/ρR 3 (s) ≈ c e / √ s when connecting two segments together where s denotes the curvilinear length of a segment, R(s) its typical size, c e ≈ 1/ρb 3 e the "swelling coefficient", b e the effective bond length and ρ the monomer density. The relative deviation of the segmental size distribution from the ideal Gaussian chain behavior is found to be proportional to u(s). The analysis of different moments of this distribution allows for a precise determination of the effective bond length b e and the swelling coefficient c e of asymptotically long chains. At striking variance to the short-range decay suggested by Flory's ideality hypothesis the bond-bond correlation function of two bonds separated by s monomers along the chain is found to decay algebraically as 1/s 3/2 . Effects of finite chain length are considered briefly. PACS numbers: 61.25.Hq,64.60.Ak,05.40.Fb * Electronic address: jwittmer@ics.u-strasbg.fr † URL: http://www-ics.u-strasbg.fr/~etsp/welcome.php 1 I. FLORY'S IDEALITY HYPOTHESIS REVISITEDA cornerstone of polymer physics. Polymer melts are dense disordered systems consisting of macromolecular chains [1]. Theories that predict properties of chains in a melt or concentrated solutions generally start from the "Flory ideality hypothesis" formulated already in the 1940s by Flory [2,3,4]. This cornerstone of polymer physics states that chain conformations correspond to "ideal" random walks on length scales much larger than the monomer diameter [1,4,5,6]. The commonly accepted justification of this mean-field result is that intrachain and interchain excluded volume forces compensate each other if many chains strongly overlap which is the case for three-dimensional melts [5]. Since these systems are essentially incompressible, density fluctuations are known to be small. Hence, all correlations are supposed to be short-ranged as has been systematically discussed first by Edwards who developed the essential statistical mechanical tools [6,7,8,9, 10] also used in this paper.One immediate consequence of Flory's hypothesis is that the mean-squared size of chain segments of curvilinear length s = m − n (with 1 ≤ n < m < N) should scale as R Both equations are expected to hold as long as the moment is not too high for a given segment length and the finite-extensibility of the polymer strand remains irrelevant [6].Deviations caused by the segmental correlation hole effect. Recently, Flory's hypothesis has been challenged both theoretically [11,12,13,14,15] and numerically for threedimensional solutions [16,17,18,19,20] and ultrathin films [21,22]. These studies suggest 2 that intra-and interchain excluded volume forces do not fully compensate each other on intermediate length scales, l...

show abstract

“…More sophisticated MC moves alter the chain conformation by rearranging a group of inner segments simultaneously. 25 In particular, the double re-bridging move, a chain connectivity altering move 36 that rearranges two neighboring chains by exchanging parts of them, is also used to improve sampling. The advantage of double rebridging vis-à-vis single end-bridging algorithms is that it preserves monodispersity, albeit at the expense of lower acceptance rates.…”

Section: A Simulationmentioning

confidence: 99%

“…35 Polyethylene chains have been recently simulated using a configurational bias double rebridging method that is easily applicable to a variety of polymeric systems. 36 The present work examines the depletion layer thickness, polymer structure near a single nanoparticle, and the chain orientation and deformation due to the presence of particles with off-lattice canonical Monte Carlo simulations. Advanced Monte Carlo techniques such as configurational bias for inner chain segments and double rebridging between two neighboring chains are employed to efficiently sample configurations and determine the monomer and chain density profile relative to the impenetrable spherical surface.…”

Section: Introductionmentioning

confidence: 99%

Polymer–particle mixtures: Depletion and packing effects

Doxastakis

Chen

Guzmán

et al. 2004

The Journal of Chemical Physics

View full text Add to dashboard Cite

The structure of polymers in the vicinity of spherical colloids is investigated by Monte Carlo simulations and integral equation theory. Polymers are represented by a simple bead-spring model; only repulsive Lennard-Jones interactions are taken into account. Using advanced trial moves that alter chain connectivity, depletion and packing effects are analyzed as a function of chain length and density, both at the bond and the chain level. Chain ends segregate to the colloidal surface and polymer bonds orient parallel to it. In the dilute regime, the polymer chain length governs the range of depletion and has a negligible influence on monomer packing in dense polymer melts. Polymers adopt an ellipsoidal shape, with the larger axis parallel to the surface of the particle, as they approach larger colloids. The dimensions are perturbed within the range of the depletion layer.

show abstract

A new double-rebridging technique for linear polyethylene

Cited by 56 publications

References 36 publications

Evolution of collective motion in a model glass-forming liquid during physical aging

Evolution of collective motion in a model glass-forming liquid during physical aging

Intramolecular long-range correlations in polymer melts: The segmental size distribution and its moments

Polymer–particle mixtures: Depletion and packing effects

Contact Info

Product

Resources

About