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Polymers
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Molecular Simulation of Polymers
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Molecular Simulation of Polymers

A special issue of Polymers (ISSN 2073-4360). This special issue belongs to the section "Polymer Physics and Theory".

Deadline for manuscript submissions: closed (5 December 2023) | Viewed by 6961

Special Issue Editor

Dr. Xinmin Shen

E-Mail Website
Guest Editor
College of Field Engineering, Army Engineering University of PLA, Nanjing, China
Interests: polymers; rubber; process parameter optimization; molecular simulation; finite element simulation

Special Issue Information

Dear Colleagues,

Simulation has been treated as a significant method to improve research efficiency, decrease experiment cost, and promote the development of novel products. It is well known that there are many influencing factors in the fabrication of polymers, which indicates that the direct experimental study to investigate and optimize the process parameters inevitably requires a great quantity of time and economic costs. Meanwhile, for the various applications of polymers, many kinds of properties are demanded to test and analyze, such as mechanical property, thermal property, electrical property, magnetic property, and chemical property, which mean a complex and costly detection process. The booming technology of simulation can make up for these existing problems by combining with theoretical modelling and experimental validation. Thus, simulation is not only feasible, but also necessary.

Many kinds of simulation methods have been developed at present, such as molecular simulation, finite element simulation, and virtual reality technology, which provide a variety of tools to develop and detect novel polymers. Molecular simulation is a method to simulate molecular structures and behaviors using computers to simulate at the atomic level, and then to simulate the various physical and chemical properties of the molecular system for polymers. Meanwhile, the finite element simulation method is treated as another promising technique to study the property of polymers or interfacial performance among polymers and other materials. This Special Issue is dedicated to recent research advances in the fabrication, characterization, and optimization of polymers via the assistance of computational simulation, more specifically, in (1) molecular simulation, (2) finite element simulation, and (3) multi-physical computational simulation in the polymer and relevant fields.

It is our pleasure to invite you to submit a manuscript to this Special Issue, including full papers, reviews, and short communications.

Dr. Xinmin Shen
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Polymers is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2700 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • polymers
  • molecular simulation
  • first principle calculation
  • finite element simulation
  • mechanical property
  • physical performance
  • rubber
  • preparation parameters
  • performance characterization

Published Papers (5 papers)

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Research

19 pages, 5602 KiB  
Article
Revealing the Effect of the Molecular Weight Distribution on the Chain Diffusion and Crystallization Process under a Branched Trimodal Polyethylene System
by Min Cai, Xuelian He and Boping Liu
Polymers 2024, 16(2), 265; https://doi.org/10.3390/polym16020265 - 18 Jan 2024
Viewed by 1130
Abstract
With the increasing demand for high-end materials, trimodal polyethylene (PE) has become a research hotspot in recent years due to its superior performance compared with bimodal PE. By means of molecular dynamics (MD) simulations, we aim to expound the effect of the molecular [...] Read more.
With the increasing demand for high-end materials, trimodal polyethylene (PE) has become a research hotspot in recent years due to its superior performance compared with bimodal PE. By means of molecular dynamics (MD) simulations, we aim to expound the effect of the molecular weight distribution (MWD) on the mechanism of nucleation and crystallization of trimodal PE. The crystallization rate is faster when short-chain branching is distributed on a single backbone compared to that on two backbones. In addition, as the content of high molecular weight backbone decreases, the time required for nucleation decreases, but the crystallization rate slows down. This is because low molecular weight backbones undergo intra-chain nucleation and crystallize earlier due to the high diffusion capacity, which leads to entanglement that prevents the movement of medium or high molecular weight backbones. Furthermore, crystallized short backbones hinder the movement and crystallization of other backbones. What is more, a small increase in the high molecular weight branched backbone of trimodal PE can make the crystallinity greater than that of bimodal PE, but when the content of high molecular weight backbone is too high, the crystallinity decreases instead, because the contribution of short and medium backbones to high crystallinity is greater than that of long backbones. Full article
(This article belongs to the Special Issue Molecular Simulation of Polymers)
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25 pages, 14466 KiB  
Article
Non-Covalent Functionalization of Graphene Oxide with POSS to Improve the Mechanical Properties of Epoxy Composites
by Ting Xu, Yumin Jiao, Zhenglian Su, Qin Yin, Lizhou An and Yefa Tan
Polymers 2023, 15(24), 4726; https://doi.org/10.3390/polym15244726 - 16 Dec 2023
Viewed by 1015
Abstract
Phenyl polyhedral oligomeric silsesquioxane (POSS) is modified onto the GO surface by using the strong π–π coupling between a large number of benzene rings at the end of the phenyl POSS structure and the graphite structure in the GO sheet, realizing the non-covalent [...] Read more.
Phenyl polyhedral oligomeric silsesquioxane (POSS) is modified onto the GO surface by using the strong π–π coupling between a large number of benzene rings at the end of the phenyl POSS structure and the graphite structure in the GO sheet, realizing the non-covalent functionalization of GO (POSS-GO). The POSS-GO-reinforced EP (POSS-GO/EP) composite material is prepared using the casting molding process. The surface morphology of GO before and after modification and its peel dispersion in EP are examined. Furthermore, the mechanical properties, cross-sectional morphology, and reinforcement mechanism of POSS-GO/EP are thoroughly examined. The results show that the cage-like skeleton structure of POSS is embedded between the GO layers, increasing the spacing between the GO layers and leading to a steric hindrance effect, which effectively prevents their stacking and aggregation and improves the dispersion performance of GO. In particular, the 0.4 phr POSS-GO/EP sample shows the best mechanical properties. This is because, on the one hand, POSS-GO is uniformly dispersed in the EP matrix, which can more efficiently induce crack deflection and bifurcation and can also cause certain plastic deformations in the EP matrix. On the other hand, the POSS-GO/EP fracture cross-section with a stepped morphology of interlaced “canine teeth” shape is rougher and more uneven, leading to more complex crack propagation paths and greater energy consumption. Moreover, the mechanical meshing effect between the rough POSS-GO surface and the EP matrix is stronger, which is conducive to the transfer of interfacial stress and the strengthening and toughening effects of POSS-GO. Full article
(This article belongs to the Special Issue Molecular Simulation of Polymers)
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18 pages, 4841 KiB  
Article
Promotion of B(C6F5)3 as Ligand for Titanium (or Vanadium) Catalysts in the Copolymerization of Ethylene and 1-Hexene: A Computational Study
by Shuyuan Yu, Chenggen Zhang, Fei Wang, Xinru Liang, Mengyao Yang and Mengyu An
Polymers 2023, 15(11), 2435; https://doi.org/10.3390/polym15112435 - 24 May 2023
Viewed by 1092
Abstract
Density functional theory (DFT) is employed to investigate the promotion of B(C6F5)3 as a ligand for titanium (or vanadium) catalysts in ethylene/1-hexene copolymerization reactions. The results reveal that (I) Ethylene insertion into TiB (with B(C6F [...] Read more.
Density functional theory (DFT) is employed to investigate the promotion of B(C6F5)3 as a ligand for titanium (or vanadium) catalysts in ethylene/1-hexene copolymerization reactions. The results reveal that (I) Ethylene insertion into TiB (with B(C6F5)3 as a ligand ) is preferred over TiH, both thermodynamically and kinetically. (II) In TiH and TiB catalysts, the 2,1 insertion reaction (TiH21 and TiB21) is the primary pathway for 1-hexene insertion. Furthermore, the 1-hexene insertion reaction for TiB21 is favored over TiH21 and is easier to perform. Consequently, the entire ethylene and 1-hexene insertion reaction proceeds smoothly using the TiB catalyst to yield the final product. (III) Analogous to the Ti catalyst case, VB (with B(C6F5)3 as a ligand) is preferred over VH for the entire ethylene/1-hexene copolymerization reaction. Moreover, VB exhibits higher reaction activity than TiB, thus agreeing with experimental results. Additionally, the electron localization function and global reactivity index analysis indicate that titanium (or vanadium) catalysts with B(C6F5)3 as a ligand exhibit higher reactivity. Investigating the promotion of B(C6F5)3 as a ligand for titanium (or vanadium) catalysts in ethylene/1-hexene copolymerization reactions will aid in designing novel catalysts and lead to more cost-effective polymerization production methods. Full article
(This article belongs to the Special Issue Molecular Simulation of Polymers)
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12 pages, 4322 KiB  
Article
Molecular Dynamics Studies of the Mechanical Behaviors and Thermal Conductivity of Polyisoprene with Different Degrees of Polymerization
by Zhiyuan Chen, Qunzhang Tu, Zhonghang Fang, Xinmin Shen, Qin Yin, Xiangpo Zhang and Ming Pan
Polymers 2022, 14(22), 4950; https://doi.org/10.3390/polym14224950 - 16 Nov 2022
Cited by 2 | Viewed by 1746
Abstract
Polyisoprene, with a high degree of polymerization, is the main component of natural rubber. In the industrial production process, it is necessary to adjust the length of the macromolecule of polyisoprene to improve its plasticity. It is thus of vital importance to explore [...] Read more.
Polyisoprene, with a high degree of polymerization, is the main component of natural rubber. In the industrial production process, it is necessary to adjust the length of the macromolecule of polyisoprene to improve its plasticity. It is thus of vital importance to explore the effect of the degree of polymerization of polyisoprene on its properties, e.g., mechanical property and thermal property. Molecular dynamics simulations link microstructure to macroscopic properties. In this paper, Moltemplate was used to establish polyisoprene models with different degrees of polymerization, and the mechanical properties of polyisoprene under uniaxial tension were analyzed under an OPLS all-atom force field. The results showed that the strength and elastic modulus of the material increased with the increase in the degree of polymerization of the molecular chain. In the process of tensile loading, the non-bonded potential energy played a dominant role in the change of the total system potential energy. Then, the thermal conductivity of polyisoprene with different degrees of polymerization was calculated by the non-equilibrium molecular dynamics method (NEMD). The thermal conductivity of PI was predicted to converge to 0.179 W/(m·K). The mechanism of thermal conductivity of the polymer containing branched chains was also discussed and analyzed. The research content of this paper aims to provide theoretical support for improving the mechanical and thermal properties of natural rubber base materials. Full article
(This article belongs to the Special Issue Molecular Simulation of Polymers)
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26 pages, 4645 KiB  
Article
Effects of Air Plasma Modification on Aramid Fiber Surface and Its Composite Interface and Mechanical Properties
by Ting Xu, Zehao Qi, Qin Yin, Yumin Jiao, Lizhou An and Yefa Tan
Polymers 2022, 14(22), 4892; https://doi.org/10.3390/polym14224892 - 13 Nov 2022
Cited by 8 | Viewed by 1427
Abstract
In order to improve the interface and mechanical properties of aramid fiber (AF)-reinforced epoxy resin (EP) composites (AF/EPs), the surface modification of AF was carried out with atmospheric pressure air plasma, and the effects of plasma treatment time and discharge power on the [...] Read more.
In order to improve the interface and mechanical properties of aramid fiber (AF)-reinforced epoxy resin (EP) composites (AF/EPs), the surface modification of AF was carried out with atmospheric pressure air plasma, and the effects of plasma treatment time and discharge power on the AF surface and the interface and mechanical properties of AF/EPs were investigated. The results show that, when plasma treatment time was 10 min and discharge power was 400 W, AF showed the best modification effect. Compared to the unmodified material, the total content of active groups on the surface of AF increased by 82.4%; the contact angle between AF and EP decreased by 20%; the interfacial energy and work of adhesion increased by 77.1% and 19.1%, respectively; the loss of AF monofilament tensile strength was controlled at only 8.6%; and the interlaminar shear strength and tensile strength of AF/EPs increased by 45.5% and 10.4%, respectively. The improvement in AF/EP interfacial and mechanical properties is due to the introduction of more active groups on the AF surface with suitable plasma processing parameters, which strengthens the chemical bonding between the AF and EP matrix. At the same time, plasma treatment effectively increases the surface roughness of AF, and the mechanical meshing effect between the AF and EP matrix is improved. The synergistic effect of chemical bonding and mechanical meshing improves the wettability and interfacial bonding strength between the AF and EP matrix, which enables the load to be transferred from the resin to the fiber more efficiently, thereby improving the mechanical properties of the AF/EP. Full article
(This article belongs to the Special Issue Molecular Simulation of Polymers)
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