Temperature-Dependent Elasticity of a Semicrystalline Interphase Composed of Freely Rotating Chains

Veld, Pieter J. in ’t; Rutledge, Gregory C.

doi:10.1021/ma0346658

Cited by 111 publications

(100 citation statements)

References 43 publications

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“…While our approach can be applied to any combination of membrane counterions and chain number, we focused on sodium as the counterion and we considered seven Nafion chains. Nafion chains and surrounding water molecules were created in the form of a three-dimensional, fully periodic membrane using the discrete particle dynamics (DPD) functionality of the Enhanced Monte Carlo molecular builder [33]. Atoms were given partial charge values following [34].…”

Section: Methodsmentioning

confidence: 99%

Molecular dynamics of ionic polymer-metal composites

Truszkowska

Porfiri

2021

Phil. Trans. R. Soc. A.

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Ionic polymer-metal composites (IPMCs) constitute a promising class of soft, active materials with potentially ubiquitous use in science and engineering. Realizing the full potential of IPMCs calls for a deeper understanding of the mechanisms underpinning their most intriguing characteristics: the ability to deform under an electric field and the generation of a voltage upon mechanical deformation. These behaviours are tightly linked to physical phenomena at the level of atoms, including rearrangements of ions and molecules, along with the formation of sub-nanometre thick double layers on the surface of the metal electrodes. Several continuum theories have been developed to describe these phenomena, but their experimental and theoretical validation remains incomplete. IPMC modelling at the atomistic scale could beget valuable support for these efforts, by affording granular analysis of individual atoms. Here, we present a simplified atomistic model of IPMCs based on classical molecular dynamics. The three-dimensional IPMC membrane is constrained by two smooth walls, a simplified analogue of metal electrodes, impermeable only to counterions. The electric field is applied as an additional force acting on all the atoms. We demonstrate the feasibility of simulating counterions’ migration and pile-up upon the application of an electric field, similar to experimental observations. By analysing the spatial configuration of atoms and stress distribution, we identify two mechanisms for stress generation. The presented model offers new insight into the physical underpinnings of actuation and sensing in IPMCs. This article is part of the theme issue ‘Progress in mesoscale methods for fluid dynamics simulation’.

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Section: Methodsmentioning

confidence: 99%

Molecular dynamics of ionic polymer-metal composites

Truszkowska

Porfiri

2021

Phil. Trans. R. Soc. A.

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“…The ensembles of configurations of semicrystalline polyethylene used in this work were generated using the Interphase Monte Carlo (IMC) method, which has been developed in a series of papers 12,13,[21][22][23][24] . Briefly, the models generated by the IMC methodology consist of a noncrystalline domain sandwiched between two static crystalline domain boundaries.…”

Section: Interphase Model By Monte Carlomentioning

confidence: 99%

“…A united-atom (UA) force field, originally developed by Paul et al 25 and modified as described by Bolton et al 26 and In't Veld et al 24 , was used in this work. This force field was originally developed to describe the structure and dynamics of polyethylene melts, where the results were compared to those obtained using an all-atom force field.…”

Section: Interphase Model By Monte Carlomentioning

confidence: 99%

Plastic Deformation of Semicrystalline Polyethylene under Extension, Compression, and Shear Using Molecular Dynamics Simulation

2014

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Plastic deformation of the stack of alternating crystal and amorphous layers typical of semicrystalline polyethylene is studied by molecular dynamics simulation. A previous investigation of the semicrystalline layered stack undergoing isochoric extension is extended here to include several new modes of deformation: isostress extension, isostress compression, and isochoric shear, at 350 K and deformation rates of 5 × 107 and 5 × 106 s–1. The observed stress–strain responses are interpreted in terms of the underlying structural evolution of the material for each mode of deformation. Under tensile deformation, crystallographic slip was observed at low strains (0 < e 3 < 0.08) regardless of deformation rate. Different yield mechanisms were observed for the different deformation rates. To explain the response at intermediate strains (0.08 < e 3 < 0.26), we introduce the concept of “bridging entanglements”, which are temporary, physical bridges between crystal lamellae comprising entanglements involving chain segments belonging to different crystal lamellae. At high strains (e 3 > 0.26), melting and recrystallization were observed at the slower deformation rate, while surface melting and cavitation were observed at the faster deformation rate. Under compressive deformation at the slower deformation rate, crystallographic slip was again observed at low strains. For the faster compressive deformation, an initial period of rapid stress growth at low strain was observed. This initial stress growth then transitions to a process of fine crystallographic slip at a strain of e 3 = −0.005. At intermediate strains under compressive deformation, the release of bridging entanglements is observed for both strain rates. However, no melting or recrystallization phenomena were observed under compression, even at the highest strains simulated (e 3 = −0.33). Under shear deformation, interlamellar slip was observed for both zx and zy shear (strain gradient parallel to stacking direction). Chain segments tend to stretch and align in the shear direction. Interestingly, under shear deformation this semicrystalline polyethylene exhibits transient behavior typical of non-Newtonian fluids.

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“…Simple Monte Carlo moves include [4]: reptation [8], endmer rotation [9], libration or flip [9], dimer flip [10,11], configurational bias (CB) [12][13][14][15], extended configurational bias [16][17][18][19][20][21][22], concerted rotation (ConRot) [23], intra-chain and interchain concerted rotation [24,25], generalized reptation [9,26], parallel rotation [27], (g) pivot [28,29], atom identity exchange [30], and volume fluctuation [9]. These moves apply only to a single polymer chain; moreover, reptation, configurational bias, end-mer rotation and generalized reptation apply only at chain ends.…”

Section: Simple Monte Carlo Movesmentioning

confidence: 99%

Using Monte Carlo to Simulate Complex Polymer Systems: Recent Progress and Outlook

Mavrantzas

2021

Front. Phys.

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Metropolis Monte Carlo has been employed with remarkable success over the years to simulate the dense phases of polymer systems. Owing, in particular, to the freedom it provides to accelerate sampling in phase space through the clever design and proper implementation of even unphysical moves that take the system completely away from its natural trajectory, and despite that it cannot provide any direct information about dynamics, it has turned to a powerful simulation tool today, often viewed as an excellent alternative to the other, most popular method of Molecular Dynamics. In the last years, Monte Carlo has advanced considerably thanks to the design of new moves or to the efficient implementation of existing ones to considerably more complex systems than those for which these were originally proposed. In this short review, we highlight recent progress in the field (with a clear emphasis in the last 10 years or so) by presenting examples from applications of the method to several systems in Soft Matter, such as polymer nanocomposites, soft nanostructured materials, confined polymers, polymer rings and knots, hydrogels and networks, crystalline polymers, and many others. We highlight, in particular, extensions of the method to non-equilibrium systems (e.g., polymers under steady shear flow) guided by non-equilibrium thermodynamics and emphasize the importance of hybrid modeling schemes (e.g., coupled Monte Carlo simulations with field theoretic calculations). We also include a short section discussing some key remaining challenges plus interesting future opportunities.

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Temperature-Dependent Elasticity of a Semicrystalline Interphase Composed of Freely Rotating Chains

Cited by 111 publications

References 43 publications

Molecular dynamics of ionic polymer-metal composites

Molecular dynamics of ionic polymer-metal composites

Plastic Deformation of Semicrystalline Polyethylene under Extension, Compression, and Shear Using Molecular Dynamics Simulation

Using Monte Carlo to Simulate Complex Polymer Systems: Recent Progress and Outlook

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