scholarly journals A Dynamically Correlated Network Model for the Collective Dynamics in Glass-Forming Molecular Liquids and Polymers

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3424
Author(s):  
Takashi Sasaki ◽  
Yuya Tsuzuki ◽  
Tatsuki Nakane
Keyword(s):  
Soft Matter ◽  
Supercooled Liquids ◽  
Arrhenius Behavior ◽  
Segmental Dynamics ◽  
Glass Forming ◽  
Segmental Relaxation ◽  
Collective Motions ◽  
Different Temperatures ◽  
Dynamical Coupling ◽  
Soft Matter Physics

The non-Arrhenius behavior of segmental dynamics in glass-forming liquids is one of the most profound mysteries in soft matter physics. In this article, we propose a dynamically correlated network (DCN) model to understand the growing behavior of dynamically correlated regions during cooling, which leads to the viscous slowdown of supercooled liquids. The fundamental concept of the model is that the cooperative region of collective motions has a network structure that consists of string-like parts, and networks of various sizes interpenetrate each other. Each segment undergoes dynamical coupling with its neighboring segments via a finite binding energy. Monte Carlo simulations showed that the fractal dimension of the DCNs generated at different temperatures increased and their size distribution became broader with decreasing temperature. The segmental relaxation time was evaluated based on a power law with four different exponents for the activation energy of rearrangement with respect to the DCN size. The results of the present DCN model are consistent with the experimental results for various materials of molecular and polymeric liquids.

COOPERATIVE FREE VOLUME RATE MODEL APPLIED TO THE PRESSURE-DEPENDENT SEGMENTAL DYNAMICS OF NATURAL RUBBER AND POLYUREA

2019 ◽  
Vol 92 (4) ◽  
pp. 612-624
Author(s):  
Ronald P. White ◽  
Jane E. G. Lipson
Keyword(s):  
Natural Rubber ◽  
Free Volume ◽  
Relaxation Times ◽  
Close Packing ◽  
Rate Model ◽  
Segmental Dynamics ◽  
Glass Forming ◽  
Segmental Relaxation ◽  
The Difference ◽  
New Applications

ABSTRACT We apply the cooperative free volume (CFV) rate model for pressure-dependent dynamics of glass-forming liquids and polymer melts, focusing on two new applications of the model, to natural rubber and to polyurea. In CFV, segmental relaxation times, τ, are analyzed as a function of temperature (T) and free volume (Vfree), where the latter provides an insightful route to expressing dynamics relative to using the system's overall total volume (V). Vfree is defined as the difference between the total volume and the volume at close packing and is predicted independently of the dynamics for any temperature and pressure using the locally correlated lattice equation-of-state analysis of characteristic thermodynamic data. The new results for natural rubber and polyurea are discussed in the context of results on a set of polymeric and small-molecule glass formers that had previously been modeled with CFV. We also discuss the results in the context of recent connections that we have made with the density-scaling approach.

Introduction to molecular simulations in soft matter

2017 ◽  
Author(s):  
J.-L. Barrat ◽  
J. J. de Pablo
Keyword(s):  
Phase Space ◽  
Numerical Methods ◽  
Theoretical Basis ◽  
Soft Matter ◽  
Relevant Literature ◽  
Coarse Grained ◽  
Soft Interfaces ◽  
Molecular Scale ◽  
Soft Matter Physics ◽  
The Continuum

We describe the main features of the coarse-grained models that are typically useful in modelling soft interfaces, from force fields to the continuum descriptions involving density fields. We explain the theoretical basis of the main numerical methods that are used to explore the phase space associated with these models. Finally, three recent examples, illustrating the spirit in which relatively simple simulations can contribute to solving pending problems in soft matter physics, are briefly described. Clearly, a short series of lectures can offer, at best, a biased and restricted view of the available approaches. Our aim here will be to provide the reader with such an overview, with a focus on methods and descriptions that ‘bridge the scale’ between the molecular scale and the continuum or quasi-continuum one. The objective to present a guide to the relevant literature—which has now to a large extent appeared in the form of textbooks.

scholarly journals Electrical Conduction Mechanism in Solid Polymer Electrolytes: New Concepts to Arrhenius Equation

2013 ◽  
Vol 2013 ◽  
pp. 1-8 ◽  
Author(s):  
Shujahadeen B. Aziz ◽  
Zul Hazrin Z. Abidin
Keyword(s):  
Dielectric Constant ◽  
Polymer Electrolytes ◽  
Conduction Mechanism ◽  
Dc Conductivity ◽  
Solid Polymer Electrolytes ◽  
Solid Polymer ◽  
Arrhenius Behavior ◽  
Different Temperatures ◽  
Solution Cast ◽  
The Fourier Transform

Solid polymer electrolytes based on chitosan NaCF3SO3 have been prepared by the solution cast technique. X-ray diffraction shows that the crystalline phase of the pure chitosan membrane has been partially disrupted. The fourier transform infrared (FTIR) results reveal the complexation between the chitosan polymer and the sodium triflate (NaTf) salt. The dielectric constant and DC conductivity follow the same trend with NaTf salt concentration. The increase in dielectric constant at different temperatures indicates an increase in DC conductivity. The ion conduction mechanism follows the Arrhenius behavior. The dependence of DC conductivity on both temperature and dielectric constant (σdc(T,ε′)=σ0e−Ea/KBT) is also demonstrated.

Application of video microscopy in experimental soft matter physics

2018 ◽  
Vol 32 (18) ◽  
pp. 1840012
Author(s):  
Hao Feng ◽  
Huaguang Wang ◽  
Zexin Zhang
Keyword(s):  
Video Processing ◽  
Soft Matter ◽  
Colloidal Suspensions ◽  
Real Space ◽  
Video Microscopy ◽  
Quantitative Image ◽  
Soft Matter Physics ◽  
Microscopic World ◽  
The One ◽  
Microscopic Measurement

Combining precise microscopic measurement with quantitative image analysis, video microscopy has become one of the most important, real-space experiment techniques to study the microscopic properties of soft matter systems. On the one hand, it provides a basic tool to observe and record the microscopic world. On the other hand, it offers a powerful experiment method to study the underlying physics of the microscopic world. In this paper, we review the development of the video microscopy, introduce the corresponding hardware and video processing software, and summarize the typical applications and recent progresses of video microscopy in colloidal suspensions. The future of the video microscopy in the soft condensed matter physics and interdisciplinary research is discussed.

scholarly journals Recent Advances in Conservation–Dissipation Formalism for Irreversible Processes

Entropy ◽  
2021 ◽  
Vol 23 (11) ◽  
pp. 1447
Author(s):  
Liangrong Peng ◽  
Liu Hong
Keyword(s):  
Soft Matter ◽  
Irreversible Processes ◽  
Recent Advances ◽  
Classical Models ◽  
Fourier Heat Conduction ◽  
Soft Matter Physics ◽  
Novel Applications ◽  
Fokker Planck Equations ◽  
Mathematical Foundations ◽  
Well Posed

The main purpose of this review is to summarize the recent advances of the Conservation–Dissipation Formalism (CDF), a new way for constructing both thermodynamically compatible and mathematically stable and well-posed models for irreversible processes. The contents include but are not restricted to the CDF’s physical motivations, mathematical foundations, formulations of several classical models in mathematical physics from master equations and Fokker–Planck equations to Boltzmann equations and quasi-linear Maxwell equations, as well as novel applications in the fields of non-Fourier heat conduction, non-Newtonian viscoelastic fluids, wave propagation/transportation in geophysics and neural science, soft matter physics, etc. Connections with other popular theories in the field of non-equilibrium thermodynamics are examined too.

scholarly journals Paraspeckles are constructed as block copolymer micelles through microphase separation

2020 ◽  
Author(s):  
Tomohiro Yamazaki ◽  
Tetsuya Yamamoto ◽  
Hyura Yoshino ◽  
Sylvie Souquere ◽  
Shinichi Nakagawa ◽  
...  
Keyword(s):  
Block Copolymer ◽  
Soft Matter ◽  
Microphase Separation ◽  
Theoretical Framework ◽  
Internal Organization ◽  
Ribonucleoprotein Complexes ◽  
Block Copolymer Micelles ◽  
Copolymer Micelles ◽  
Rna Domains ◽  
Soft Matter Physics

SummaryParaspeckles are constructed by NEAT1_2 architectural long noncoding RNAs and possess characteristic cylindrical shapes with highly ordered internal organization, distinct from typical liquid–liquid phase-separated condensates. We experimentally and theoretically investigated how the shape and organization of paraspeckles are determined. We identified the NEAT1_2 RNA domains responsible for shell localization of the NEAT1_2 ends, which determine the characteristic internal organization. We then applied a theoretical framework using soft matter physics to understand the principles that determine the NEAT1_2 organization, shape, number, and size of paraspeckles. By treating paraspeckles as amphipathic block copolymer micelles, we could explain and predict the experimentally observed behaviors of paraspeckles upon NEAT1_2 domain deletions or transcriptional modulation. Thus, we propose that paraspeckles are block copolymer micelles assembled through microphase separation. This work provides an experimentally-based theoretical framework for the concept that ribonucleoprotein complexes (RNPs) can act as block copolymers to form RNA-scaffolding microphase-separated condensates in cells.

scholarly journals Glass Transition and Interfacial Segmental Dynamics in Polymer-Particle Composites

2008 ◽  
Vol 81 (3) ◽  
pp. 506-522 ◽  
Author(s):  
C. G. Robertson ◽  
C. M. Roland
Keyword(s):  
Glass Transition ◽  
Relaxation Times ◽  
Polymer Particle ◽  
Polymer Chains ◽  
Nano Particle ◽  
Segmental Mobility ◽  
Segmental Dynamics ◽  
Reinforcing Fillers ◽  
Segmental Relaxation ◽  
Polymer Interaction

Abstract We review the literature concerned with the effect of proximity to a filler surface on the local segmental mobility of polymer chains. This mobility is commonly assessed from either the glass transition temperature, Tg, or the segmental relaxation times measured by mechanical, dielectric, or NMR spectroscopy. Published studies report increases, decreases, or no change in Tg upon the addition of carbon black, silica, and other reinforcing fillers. Similarly, the segmental relaxation times have been found to increase or be invariant to the presence of nanometer-sized particles. Some of these discrepancies can be ascribed to ambiguous methods of data analysis; others likely reflect the variation in filler-polymer interaction among different systems. There are unequivocal examples of polymers that have segmental dynamics and glass transitions unaffected by nano-particle reinforcement. However, the general principles governing the behavior remain to be clarified, with further work, focusing on the micromechanics at the particle interface, required for resolution of this important aspect of rubber science and technology.

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