| POLYMERS Vol.70 No.3 |
| >> Japanese | >> English |
COVER STORY
Cyber Polymer |
| COVER STORY: Highlight Reviews |
| Large-Scale All-Atomistic Molecular Dynamics Calculations of Polymers | Susumu OKAZAKI |
| <Abstract> A perspective review of large-scale all-atomistic molecular dynamics (MD) studies of mechanical properties of polymers is presented. A coarse-grained model rather than all-atomistic model has been a leading simulation technique in the conventional calculations. This is caused by a limitation of performance of computers. Most of the MD calculations of polymers reported so far have been based on this bead-spring model, where universal properties of the polymer were investigated. An abundance of physics was obtained by it. However, the model has lost the chemical details of the polymers. Thus, it is not possible to discuss mechanical properties of polymers as a function of their chemical structures. Recent development of supercomputers such as K computer and Fugaku can solve this problem. Million-atom simulations are no more than everyday calculations. This will present a very powerful tool for the investigation of fracture of polymers from a chemical viewpoint. We introduce our recent large-scale all-atomistic MD calculations. Keywords: Molecular Dynamics Calculation / All-Atomistic Calculation / Large-Scale Calculation / Fracture of Polymers |
| Top of the Page▲ |
| Foresight of Collaborative Study of Both Simulation and Data Science in the Age of Digital Transformation in Materials | Hiroshi MORITA |
| <Abstract> Recently, the focused point in R&D of materials informatics is moved to datasets within a planning of the digital transformation in materials, and the importance of data is increasing. In this review, the foresight of collaborative study of simulation and data science is described in the point of view from data. In the area of polymer science, the higher order structure is one of the typical feature and we study its descriptor using graph theory or other mathematical techniques. The network structure of the thermoplastic elastomer made from ABA triblock copolymers can be described by the parameter derived from graph theory and we can classify the irreversible deformation by those parameters. Another important point is the data collection technique using simulations and measuring experiments and these topics are also discussed. Keywords: Higher Order Structure / Descriptor / Scattering Matrix / Correlation Coefficient / OCTA |
| Top of the Page▲ |
| Prospects for Correlation Function Analysis in Molecular Dynamics Simulations | Katsumi HAGITA |
| <Abstract> Correlation function analyses are powerful tools for trajectory data in molecular dynamics simulations of polymer systems. In this manuscript, the basics of polymer physics are introduced from viewpoints of the connectivity matrix. The relationship with the relaxation mode analysis is presented for a help of readers’ understanding. Recent progress of improving the evaluating method of the relaxation mode analysis from the time correlation functions is explained. In addition, recent progress on the calculation method of the time correlation function such as the scattering function are also reviewed. Keywords: Molecular Dynamics Simulation / Polymer Physics / Relaxation Mode Analysis / Time Correlation Function / Scattering Functions |
| Top of the Page▲ |
| COVER STORY: Topics and Products |
| Multiscale Analysis of Rubber | Hiroshi SHIMA |
| <Abstract> Tires are required to have conflicting functions such as low rolling resistance and high wear resistance. In order to achieve these conflicting functions, appropriate control of the viscoelasticity of rubber, the main material of the tire, is necessary. A multiscale approach is required for the viscoelasticity of rubber, which is a nanocomposite composed of fillers such as carbon black and silica, polymers such as natural and synthetic rubbers, and other chemicals. We report on the viscoelasticity prediction of rubber based on the property values near the interface based on molecular dynamics predictions of interfacial kinetics using the finite element method. Keywords: Simulation / Multiscale / Rubber / Composite / Finite Element Analysis / Molecular Dynamics |
| Top of the Page▲ |
| Cyber Polymer as Structure-Property Relationship Using Higher Order Structural Descriptor | Yoshifumi AMAMOTO, Hiroteru KIKUTAKE, Takaaki OHNISHI |
| <Abstract> Recently our achievement in structure-property relationship of polymers with higher order structure based on data science methodology was introduced. The mesoscopic descriptor of elastomers in terms of connectivity was developed by complex network analysis, which described some parameters related to stress. In addition, hierarchical structure-property relationship of crystalline polymers was constructed using a higher order descriptor obtained from X-ray images. These approaches enable us to predict desirable properties of polymers with important higher order structure interpreted. Keywords: Data Science / Structure-Property Relationship / Higher Order Structure |
| Top of the Page▲ |
| Analysis of Interactions between Ions by QM Calculations and MD Simulations of Transport Properties of Ionic Liquids | Seiji TSUZUKI |
| <Abstract> Intermolecular interactions in ion pairs of ionic liquids were studied by ab initio MO calculations. Self-diffusion coefficients of ions in ionic liquids were studied using MD simulations. The relationship between the intermolecular interactions and self-diffusion coefficients of ions was discussed. Keywords: Ionic Liquid / Intermolecular Interaction / Self-Diffusion Coefficient / Ab Initio Calculation / Molecular Dynamics Simulation |
| Top of the Page▲ |
| Predicting Chemical Reactions via Quantum Chemical Calculations | Satoshi MAEDA |
| <Abstract> Recently, the importance of prediction of properties, structures, etc. has been rapidly growing in chemistry. Predicting something by an informatics approach from big data has become a recent trend. On the other hand, predicting chemical reactions from the first principles via quantum chemical calculations is the subject of this article. This got possible in simple systems, by utilizing an automated reaction path search method called artificial force induced reaction (AFIR) method. It is also possible to automatically identify the product and related reaction pathways, by applying a kinetics method called rate constant matrix contraction (RCMC) method to reaction path networks obtained by the AFIR method. In this article, three examples are presented: (1) Wöhler synthesis, (2) difluoroglycine derivative synthesis, and (3) thermal transformation of amorphous carbon under existence of carbon nanotube yarn. With these examples, it is demonstrated that the combined AFIR and RCMC methods are highly promising for ab initio prediction of chemical reactions. Keywords: Quantum Chemical Calculation / Density Functional Theory / Reaction Path Network / Chemical Kinetics / Artificial Force Induced Reaction (AFIR) / Rate Constant Matrix Contraction (RCMC) |
| Top of the Page▲ |
| Polymer Science and I: A Personal Account |
| Believe in “Connecting the Dots” | Kazutoshi IIJIMA |
| <Abstract> The story of “Connecting the Dots” by Steve Jobs gives us courage when we try new things. In this essay, I describe the story of my research history, start-up of laboratory, and recent research topics. |
| Top of the Page▲ |
| Front-Line Polymer Science |
| Directed-Assembly of Amphiphilic Nanoparticles | Takuya NAKASHIMA |
| <Abstract> Amphiphilic modification on the nanoparticle (NP) surface is a versatile strategy to obtain NP assemblies since the hydrophobic effect is ubiquitous and a guiding principle for the organization of biological molecules such as proteins and biomembranes. Amphiphilic designs on the surface of NPs have been achieved through the modifications of NPs with amphiphilic molecules or a combination of both hydrophilic and hydrophobic ligands. The intrinsic hydrophobicity of most inorganic surfaces is also utilized to make the surface of NPs amphiphilic. NPs with anisotropic morphologies such as nanorods and branched NPs are successfully modified with patterned surface of hydrophilic and hydrophobic domains. Such the nanometer-scale chemical heterogeneity has an important effect on the effective operation of hydrophobic interactions. The combination of shape of NPs and amphiphilic surface pattern readily leads to NPs assembly with well defined structures. Keywords: Self-Assembly / Nanoparticles / Amphiphiles / Electrostatic Interaction / Hydrophobic Effect |
| Top of the Page▲ |
| Copyright(C) 2021 The Society of Polymer Science, Japan All Rights Reserved. |