Voronoi space division of a polymer: Topological effects, free volume, and surface end segregation

Tokita, Nakako; Hirabayashi, Megumi; Azuma, Chiaki; Dotera, Tomonari

doi:10.1063/1.1629678

Cited by 27 publications

(18 citation statements)

References 45 publications

(29 reference statements)

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The effect vanishes in the glassy state, again, because of the large size of the PC monomer. The large volume at the chain ends correlates with the higher mobility of the chain end monomers and is consistent with previous united atom study [49]. These results suggest that the chain ends have higher flexibility enhanced by the larger local volume than the middles, especially in the melt state.…”

Section: End Effectsupporting

confidence: 91%

All-atomistic molecular dynamics study of the glass transition of amorphous polymers

Tang

Okazaki

2021

Preprint

View full text Add to dashboard Cite

Glass transition is an important phenomenon of polymer materials and it has been intensively studied over the past a few decades. However, the influencing factors arising from the chemical structures of the polymers are often ignored due to a continuous or coarse-grained description of the polymer. Here, we approached this phenomenon using all-atomistic molecular dynamics (MD) simulations and two conventionally used polymer materials, polycarbonate (PC) and poly-(methyl methacrylate) (PMMA). We reproduced the glass transition temperatures (Tg) of the two materials reasonably well. Then we characterized and investigated the glass transition process by looking at the changes of potential energy, dihedral transition, and thermal fluctuation of the individual degrees of freedom in the systems, over the entire temperature range of glass transition. As previously reported, the dihedral angles stop their conformational changes gradually at the Tg, especially for the main chain dihedrals, and sidechain rotations immediately rooting from the main chain. The volumetric change during the temperature decrease is confirmed to be because of conformational adjustment, probably due to the tendency of chain stretching for the maintenance of the radius of gyration, and the loss of thermal energy. The strength of motions of single degrees of freedom and polymer chains, and overall slow motions obtained by normal mode analysis (NMA) shows that different motions at different spatial scale may gradually stop at distinct temperature in the MD simulation temporal and spatial scales. Presumably, the small spatial scale do not contribute to the glass transition at the experimental scale since the timescale is much longer than their relaxation time.

show abstract

Section: End Effectsupporting

confidence: 91%

All-atomistic molecular dynamics study of the glass transition of amorphous polymers

Tang

Okazaki

2021

Preprint

View full text Add to dashboard Cite

show abstract

“…This result would have important implications for the dynamics of chain systems such as molecules, proteins, polymers, and some artificial objects. For example, in polymer science, it is well known that atoms situated near the ends of the polymer chain have characteristic behavior called the "end effect" [14]. Apparent violation of equipartition of energy we found in planar chain systems can be closely related to the origin of the end effect of polymers.…”

mentioning

confidence: 57%

Apparent violation of equipartition of energy in constrained dynamical systems

Konishi,

Yanagita

2008

Preprint

View full text Add to dashboard Cite

We propose a planar chain system, which is a simple mechanical system with a constraint. It is composed of N masses connected by N − 1 light links. It can be considered as a model of a chain system, e.g., a polymer, in which each bond is replaced by a rigid link. The long time average of the kinetic energies of the masses in this model is numerically computed. It is found that the average kinetic energies of the masses are different and masses near the ends of the chain have large energies. We explain that this result is not in contradiction with the principle of equipartition. The apparent violation of equipartition is observed not only in the planar chain systems but also in other constrained systems. We derive an approximate expression for the average kinetic energy, which is in qualitative agreement with the numerical results.

show abstract

“…Researchers have predominantly used Voronoi tessellations in various fields in the geometric design ranging from the division of spaces [27,28] to cellular and polycrystalline structures [29,30]. Laguerre-Voronoi (LV) tessellation is a kind of Voronoi tessellation with weights attached to each seed that determine the size and shape of the cell it produces.…”

Section: Construction Of the Generic Laguerre-voronoi Modelmentioning

confidence: 99%

Predicting the elastic properties of closed-cell aluminum foams: a mesoscopic geometric modeling approach

2019

View full text Add to dashboard Cite

The biggest challenge in predicting the elastic properties of closed-cell aluminum foams is capturing the actual geometrical and topological characteristics precisely and efficiently such that the model can be used to predict the mechanical properties of the real foam accurately. This paper presents a mesoscopic modeling approach for constructing a geometric model that captures these characteristics and can be used to predict its elastic properties. The modeling approach introduces a new method for finding the number of seeds based on the cell diameter distribution and an algorithm for computing and assigning the irregular cell wall thickness based on reverse bubble growth. Results from the foam models developed in this work were found to have better accuracy in capturing the geometrical and topological characteristics of the real foam. All foam models generated by the proposed modeling approach have the same cell size distribution and irregular cell wall distribution as the real foam. The models have cells with around 14 faces with 5 edges on each face which is similar to real metal foams and naturally occurring foams. Numerical results from the foam models showed a better accuracy in predicting the relative Young's modulus of the real foam than the generic Laguerre-Voronoi, Kelvin, and Grenestedt models.

show abstract

Voronoi space division of a polymer: Topological effects, free volume, and surface end segregation

Cited by 27 publications

References 45 publications

All-atomistic molecular dynamics study of the glass transition of amorphous polymers

All-atomistic molecular dynamics study of the glass transition of amorphous polymers

Apparent violation of equipartition of energy in constrained dynamical systems

Predicting the elastic properties of closed-cell aluminum foams: a mesoscopic geometric modeling approach

Contact Info

Product

Resources

About