Calculation of the effect of macromolecular architecture on structure and thermodynamic properties of linear–tri-arm polyethylene blends from Monte Carlo simulation

Rissanou, Anastassia N.; Peristeras, Loukas D.; Economou, Ioannis G.

doi:10.1016/j.polymer.2007.04.066

Cited by 7 publications

(12 citation statements)

References 64 publications

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“…Remarkably, this potential makes differences between CH 2 and CH 3 interaction sites. The TraPPE-UA FF has shown to be applicable to a number of polymers giving a good description of their behavior in the melt. − …”

Section: Methodsmentioning

confidence: 99%

“…This procedure allowed these authors to observe a forced crystallization at time scales accessible via large-scale MD simulations. The second FF is the so-called TraPPe-UA (transferable potentials for phase equilibria, united atom version), developed by Siepmann’s group and parametrized against fluid-phase equilibrium data of linear and branched alkanes. − MD simulations using the TraPPe-UA FF have been extensively used for the study of static and dynamic properties of PE melts, including the effect of molecular length and short chain branching. − Yamamoto et al have also used this FF for the study of “induced” crystallization processes in polypropylene (PP), but as far as we know, it has not been yet employed to simulate the homogeneous crystallization process of PE.…”

Section: Introductionmentioning

confidence: 99%

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Molecular Dynamics Simulations for the Description of Experimental Molecular Conformation, Melt Dynamics, and Phase Transitions in Polyethylene

2015

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Long molecular dynamics simulations of the melt dynamics, glass transition and nonisothermal crystallization of a C 192 polyethylene model have been carried out. In this model, the molecules are sufficiently long to form entanglements in the melt and folds in the crystalline state. On the other hand, the molecules are short enough to enable the use of atomistic simulations on a large scale of time. Two force fields, widely used for polyethylene, are taken into account comparing the simulation results with a broad set of literature experimental data. Although both force fields are able to capture the general physics of the system, TraPPe-UA is in a better quantitative agreement with the experimental data. According with the simulation results some fundamental aspects of polyethylene physical parameters are discussed such as the characteristic ratio (C n = 8.2 and 7.6 at 500 K, for TraPPe-UA and PYS force fields, respectively), the isothermal compressibility (α = 8.57 × 10 −4 K −1 ), the static structure factor and the melt dynamics regimes corresponding to an entangled polymer. Furthermore, the simulated T g (187.0 K) obtained for linear PE is in a very good agreement with the extrapolated T g values (185−195 K) using the Gordon−Taylor equation. Finally, the simulation of the nonisothermal crystallization process supports the view of a mixed state of adjacent and nonadjacent re-entry model. The simulated two phase model reproduces very well the initial fold length expected for high supercoolings and the segregation of the system in ordered and disordered layers. The paper highlights the importance of combining simulation techniques with experimental data as a powerful means to explain the polymer physics.

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Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Molecular Dynamics Simulations for the Description of Experimental Molecular Conformation, Melt Dynamics, and Phase Transitions in Polyethylene

2015

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“…For organic molecules, the simpler and more efficient representation, known as TraPPE−united atom (UA), represents CH x groups (where 0 ≤ x ≤ 4) as united atoms that interact via Lennard-Jones 12−6 and Coulombic potentials (the latter only for UA sites next to a polar group). − The TraPPE−explicit hydrogen (EH) version − is more accurate, but also more computationally expensive since the number of interaction sites increases by a factor of about 3. The polarizable version (TraPPE−pol) adds additional interaction sites, and both the partial charges and the Lennard-Jones parameters respond to changes in the environment. , Although the TraPPE−UA force field has been successfully applied for the prediction of phase equilibria and other thermophysical properties of neat polymers and polymer−solvent mixtures, − such simulations are extremely challenging and require large computational resources. Thus, a simple, transferable coarse-grain force field that reproduces many thermophysical properties over the entire stability range of fluid phases is highly desirable.…”

Section: Introductionmentioning

confidence: 99%

Transferable Potentials for Phase Equilibria−Coarse-Grain Description for Linear Alkanes

Maerzke

Siepmann

2011

J. Phys. Chem. B

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Coarse-grain potentials allow one to extend molecular simulations to length and time scales beyond those accesssible to atomistic representations of the interacting system. Since the coarse-grain potentials remove a large number of interaction sites and, hence, a large number of degrees of freedom, it is generally assumed that coarse-grain potentials are not transferable to different systems or state points (temperature and pressure). Here we apply lessons learned from the parametrization of transferable atomistic potentials to develop a systematic procedure for the parametrization of transferable coarse-grain potentials. In particular, we apply an iterative Boltzmann optimization for the determination of the bonded interactions for coarse-grain beads belonging to the same molecule and separated by one or two coarse-grain bonds and parametrize the nonbonded interactions by fitting to the vapor-liquid coexistence curves computed for selected molecules represented by the TraPPE-UA (transferable potentials for phase equilibria-united atom) force field. This approach is tested here for linear alkanes where parameters for C(3)H(7) end segments and for C(3)H(6) middle segments of the TraPPE-CG (transferable potentials for phase equilibria-coarse grain) force field are determined and it is shown that these parameters yield quite accurate vapor-liquid equilibria for neat n-hexane to n-triacontane and for the binary mixture of n-hexane and n-hexatriacontane. In addition, the position of the first peak in various radial distribution functions and the coordination number for the first solvation shell are well reproduced by the TraPPE-CG force field, but the first peaks are too high and narrow.

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“…Therefore, atomistic simulations of blends are still relatively scarce. So far, most studies have focussed on miscibility aspects [174][175][176][177][178][179][180][181][182][183][184]. Already early on, atomistic and mesoscopic simulations were combined in multiscale studies: Atomistic simulations were used to determine the Flory-Huggins χ -parameter, coarse-grained methods were then applied to study large-scale aspects of phase separation [185][186][187][188][189][190][191] or mesophase formation [192].…”

Section: Atomistic Modelsmentioning

confidence: 99%

“…So far, most studies have focussed on miscibility aspects. [174][175][176][177][178][179][180][181][182][183][184] Already early on, atomistic and mesoscopic simulations were combined in multiscale studies: Atomistic simulations were used to determine the Flory-Huggins χ-parameter, coarse-grained methods were then applied to study large-scale aspects of phase separation [185][186][187][188][189][190][191] or mesophase formation. 192 Only few fully atomistic studies deal with aspects beyond miscibility, e.g, the formation of lamellar structures in diblock copolymers, 193 or the diffusion of small molecules in blends.…”

Section: Iv21 Atomistic Modelsmentioning

confidence: 99%

Theory and Simulation of Multiphase Polymer Systems

Schmid

2011

Handbook of Multiphase Polymer Systems

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The theory of multiphase polymer systems has a venerable tradition. The 'classical' theory of polymer demixing, the Flory-Huggins theory, was developed in the 1940s [1,2]. It is still the starting point for most current approaches -be they improved theories for polymer (im)miscibility that take into account the microscopic structure of blends more accurately, or sophisticated field theories that allow to study inhomogeneous multicomponent systems of polymers with arbitrary architectures in arbitrary geometries. In contrast, simulations of multiphase polymer systems are quite young. They are still limited by the fact that one must simulate a large number of large molecules in order to obtain meaningful results. Both powerful computers and smart modeling and simulation approaches are necessary to overcome this problem.In the limited space of this chapter, we can only give a taste of the state-of-the-art in both areas, theory and simulation. Since the theory has reached a fairly mature stage by now, many aspects of it are covered in textbooks on polymer physics [3][4][5][6][7][8][9]. The information on the state-of-the art of simulations is much more scattered. This is why we have put some effort into putting together a representative list of references in this area -which is of course still far from complete.The chapter is organized as follows. In Section II, we briefly introduce some basic concepts of polymer theory. The purpose of this part is to make the chapter accessible to readers who are not very familiar with polymer physics; it can safely be skipped by the others. Section III is devoted to the theory of multiphase polymer systems. We recapitulate the Flory-Huggins theory and introduce in particular the concept of the Flory interaction parameter (the χ parameter), which is a central ingredient in most theoretical descriptions of multicomponent polymer systems. Then we focus on one of the most successful mean-field theories for inhomogeneous (co)polymer blends, the self-consistent field theory. We sketch the main idea, discuss various Handbook of Multiphase Polymer Systems, First Edition. Edited by Abderrahim Boudenne, Laurent Ibos, Yves Candau, and Sabu Thomas.

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Calculation of the effect of macromolecular architecture on structure and thermodynamic properties of linear–tri-arm polyethylene blends from Monte Carlo simulation

Cited by 7 publications

References 64 publications

Molecular Dynamics Simulations for the Description of Experimental Molecular Conformation, Melt Dynamics, and Phase Transitions in Polyethylene

Molecular Dynamics Simulations for the Description of Experimental Molecular Conformation, Melt Dynamics, and Phase Transitions in Polyethylene

Transferable Potentials for Phase Equilibria−Coarse-Grain Description for Linear Alkanes

Theory and Simulation of Multiphase Polymer Systems

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