Macromolecular Theory and Simulations最新文献_第5页

Masthead: Macromol. Theory Simul. 6/2023 刊头：Macromol.理论模拟6/2023

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2023-11-20 DOI: 10.1002/mats.202370012

引用次数: 0

Potential of Mean Force of Short-Chain Surface Adsorption using Non-Uniform Sampling Windows for Optimal Computational Efficiency 利用非均匀采样窗口优化计算效率的短链表面吸附平均力潜力

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2023-10-12 DOI: 10.1002/mats.202300057

Naveen Kumar Vasudevan, Dongyang Li, Li Xi

{"title":"Potential of Mean Force of Short-Chain Surface Adsorption using Non-Uniform Sampling Windows for Optimal Computational Efficiency","authors":"Naveen Kumar Vasudevan, Dongyang Li, Li Xi","doi":"10.1002/mats.202300057","DOIUrl":"10.1002/mats.202300057","url":null,"abstract":"Free energy calculation in molecular simulation is an computationally expensive process. Umbrella sampling (US) is a go-to method for obtaining the potential of mean force (PMF) along a reaction coordinate. Its computational cost increases drastically as the molecular system gets more complex. For many polymeric and biomolecular systems, adequately sampling all configurational degrees of freedom is computationally prohibitive. Using the adsorption of a short-chain methylcellulose on a cellulose crystalline surface as the test case, this study shows that the sampling time required for reliable results is much higher than typical choices made in the literature. The accuracy of the PMF profile is strongly affected by sampling inadequacy in a few regions along the reaction coordinate. Non-uniform windows and sampling parameters are proposed to enhance the sampling in difficult regions. Sampling windows that vary with the local PMF steepness are allocated with a new algorithm. Parameters in this algorithm are optimized for the best sampling efficiency. It is demonstrated that significantly less computer time will be required to achieve the same sampling accuracy if computational resources are optimally distributed along the reaction coordinate.","PeriodicalId":18157,"journal":{"name":"Macromolecular Theory and Simulations","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-10-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mats.202300057","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135824178","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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Improving Mixing by Changing Topology Through Intermeshed Perturbation Rings in A Co-Rotating Non-Twin Screw Channel 在同向非双螺旋通道中通过间隙扰动环改变拓扑结构改善混合效果

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2023-10-05 DOI: 10.1002/mats.202300048

Baiping Xu, Ruifeng Liang, Shuping Xiao, Yanhong Feng, Huiwen Yu

{"title":"Improving Mixing by Changing Topology Through Intermeshed Perturbation Rings in A Co-Rotating Non-Twin Screw Channel","authors":"Baiping Xu, Ruifeng Liang, Shuping Xiao, Yanhong Feng, Huiwen Yu","doi":"10.1002/mats.202300048","DOIUrl":"10.1002/mats.202300048","url":null,"abstract":"A new kind of perturbation ring element (PRE) is first proposed to introduce a repetitive topology of splitting and recombination across the intermeshing zones of a co-rotating non-twin screw elements (NTSE) with a speed ratio of 2. A numerical simulation is performed using finite element method (FEM) along with the mesh superposition technique (MST). Post-treatment codes are successfully developed where fourth-order Runge–Kutta scheme is used to achieve particle tracking. For the tracer particle groups released initially from the upper and bottom intermeshing regions, mixing is characterized in terms of the evolution of tracer particles, mixing variance index, and residence time distribution (RTD). The numerical results revealed for a given output, the larger the screw speed, the larger the dividing ratio, and the better distributive mixing is. PRE achieved the best distributive mixing owing to the changing of flow topology. In TSE there are Komogorov-Arnold-Moser (KAM) tubes in which the tracer particles are confined to prevent better mixing from occurring.","PeriodicalId":18157,"journal":{"name":"Macromolecular Theory and Simulations","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-10-05","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136184196","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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Improvement of the Mathematical Model for Quality Assurance in the Determination of Kinetic Parameters of Thermal Degradation of Polypropylene Through Thermogravimetric Analysis 改进通过热重分析确定聚丙烯热降解动力学参数的质量保证数学模型

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2023-09-27 DOI: 10.1002/mats.202300038

Esteban Fregoso-Israel, Ángeles Olvera-Treviño, Juan Enrique Romero-Hernández, Gerardo Omar Hernández-Segura, Carlos Álvarez-Maciel

{"title":"Improvement of the Mathematical Model for Quality Assurance in the Determination of Kinetic Parameters of Thermal Degradation of Polypropylene Through Thermogravimetric Analysis","authors":"Esteban Fregoso-Israel, Ángeles Olvera-Treviño, Juan Enrique Romero-Hernández, Gerardo Omar Hernández-Segura, Carlos Álvarez-Maciel","doi":"10.1002/mats.202300038","DOIUrl":"10.1002/mats.202300038","url":null,"abstract":"Robust mathematical treatment of the Ozawa/Flynn/Wall isoconversion method is conducted to determine the value and uncertainty of the activation energy and pre-exponential factor for the degradation of polypropylene in thermogravimetric analysis experiments at constant heating rates. The present work employs mathematical models and uncertainty propagation techniques based on the Guide to the Expression of Uncertainty in Measurement to estimate the Arrhenius activation energy and pre-exponential factor due to the uncertainty of the integration constant b, both in a linear and a third-degree reciprocal polynomial model with respect to x. The error arising from Doyle's linear approximation in the improper integral of temperature in the Arrhenius equation is examined, and an alternative method is proposed to correct this error, reducing it to 0.032% in the working interval of −200 ≤ x ≤ −15, where x = −E/RT. Given the increased sensitivity of modern thermogravimetric analysis equipment, these improvements are considered essential for obtaining reliable results that align with experimental precision limits compared to previous works. Thus, this allows for the development of an enhanced quality assurance framework by providing more robust uncertainty estimation and a better understanding of the method. Moreover, this approach can be applied to other similar polymer system.","PeriodicalId":18157,"journal":{"name":"Macromolecular Theory and Simulations","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1002/mats.202300038","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"136183727","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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Masthead: Macromol. Theory Simul. 5/2023 刊头：Macromol。理论模拟。2023年5月

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2023-09-15 DOI: 10.1002/mats.202370010

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Kelvin's Tetrakaidecahedron as a Wigner–Seitz Cell Found in Spherically Microphase-Separated BCC Lattice from AB Diblock Copolymer by Monte Carlo Simulation 蒙特卡罗模拟在AB二嵌段共聚物球形微相分离BCC晶格中发现的作为Wigner–Seitz单元的Kelvin十面体

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2023-09-15 DOI: 10.1002/mats.202370009

Jiro Suzuki, Yushu Matsushita

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Effect of In-Plane Electric Field on the Microphase Separation in Thin Films of a Symmetric ABA Triblock Copolymer 平面内电场对对称 ABA 三嵌段共聚物薄膜微相分离的影响

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2023-09-09 DOI: 10.1002/mats.202300049

Yury A. Kriksin, Yaroslav V. Kudryavtsev

{"title":"Effect of In-Plane Electric Field on the Microphase Separation in Thin Films of a Symmetric ABA Triblock Copolymer","authors":"Yury A. Kriksin, Yaroslav V. Kudryavtsev","doi":"10.1002/mats.202300049","DOIUrl":"10.1002/mats.202300049","url":null,"abstract":"The structure of a thin film of symmetric ABA triblock copolymer melts in an external in-plane DC or AC electric field is studied theoretically. The situation is considered when the triblock copolymer forms a hexagonal morphology of standing cylinders in bulk in the absence of an external field. Self-consistent field theory calculations are carried out to determine the most thermodynamically favorable thin film structure among the cylindrical phases perpendicular and parallel to the substrate and the lamellar phase perpendicular to the substrate. The results are presented as phase diagrams with the film thickness and electric field energy on the axes and as distributions of the local composition, which serve as an order parameter in the system. It is confirmed that electric fields only weakly affect the spinodal curves of block copolymers but they can reorient or markedly modify microphase-separated morphologies in those systems. Such restructuring is consistent with a considerable modulation of the free surface of a copolymer film and it can lead to the coexistence of different phases that appear in the film areas with different local thicknesses.","PeriodicalId":18157,"journal":{"name":"Macromolecular Theory and Simulations","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"135790445","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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Effectiveness of DPD Simulations to Predict the Dynamics of Polymer Chains in Solutions at Equilibrium and Steady Shear Flows DPD模拟在平衡和稳定剪切流动中预测聚合物链动力学的有效性

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2023-08-27 DOI: 10.1002/mats.202300045

Praphul Kumar, Sanjay Jana, Hari Shyam, Indranil Saha Dalal

{"title":"Effectiveness of DPD Simulations to Predict the Dynamics of Polymer Chains in Solutions at Equilibrium and Steady Shear Flows","authors":"Praphul Kumar, Sanjay Jana, Hari Shyam, Indranil Saha Dalal","doi":"10.1002/mats.202300045","DOIUrl":"10.1002/mats.202300045","url":null,"abstract":"The suitability of dissipative particle dynamics simulations is investigated to predict the dynamics of polymer chains in dilute polymer solutions. The authors find that the predictions depend on the value of the repulsive parameter for bead-bead pairwise interactions used in the DPD simulations (aij). For all systems, the chain sizes and the relaxation time spectrum are analyzed. For aij = 0, theta solvent behaviour is obtained, whereas the dynamics at equilibrium agrees well with the predictions of the Zimm model. For higher values of aij, the static properties of the chain show good solvent behaviour. However, the scaling laws for the chain dynamics at equilibrium show wide variations, with consistent results obtained only at an intermediate value of aij = 25. At higher values of the repulsive parameter (aij ⩾ 25), the simulations are also able to predict the abrupt cut-off in the relaxation spectrum, which has been observed earlier in experiments of dilute solutions. To verify further, the chain dynamics in shear flow using DPD simulations is studied. Specifically, the variation of the chain is analysed stretch and end-over-end tumbling with shear rates. Overall, the trends obtained from DPD simulations agree well with those observed in earlier BD simulations.","PeriodicalId":18157,"journal":{"name":"Macromolecular Theory and Simulations","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-08-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"48772823","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Comparison of Linear and Ring Polymers Partitioning into Pores Using Random Walks and Self-Avoiding Walks Models 使用随机行走和自避免行走模型的线性和环状聚合物在孔隙中分配的比较

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2023-08-19 DOI: 10.1002/mats.202300039

Christopher Alexander Litle, Yongmei Wang

{"title":"Comparison of Linear and Ring Polymers Partitioning into Pores Using Random Walks and Self-Avoiding Walks Models","authors":"Christopher Alexander Litle, Yongmei Wang","doi":"10.1002/mats.202300039","DOIUrl":"10.1002/mats.202300039","url":null,"abstract":"Monte Carlo simulations that examine the partitioning of dilute solutions of ring or linear chains into a slit pore using two chain models, the random-walk (RW) model and the self-avoiding walk (SAW) model are presented. The partitioning coefficients K for the ring and the linear chains at the surface interaction both under the critical adsorption point (CAP) and above the CAP are compared. In both chain models, K for the ring remains larger than K for the linear chains. The ring chain crosses over the point K = 1 at a weaker surface interaction than the linear chain. When extrapolated to infinite chain length, the cross-over point for the ring and linear chain becomes the same (within statistical errors) for the RW model but remains different for the SAW model. The density profiles of the ring within the pore reveal the development of humps near the wall as the surface interaction crosses over the CAP. The excluded volume interaction in the SAW model additionally impacts the partitioning of chains in a solution consisting of a binary mixture of ring and linear chains and makes the K values in a binary mixture differ from the monodispersed solutions.","PeriodicalId":18157,"journal":{"name":"Macromolecular Theory and Simulations","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42281190","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

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Mesoscopic Simulation of Centrifugal Melt Electrospinning of PPESK PPESK离心熔融静电纺丝的细观模拟

IF 1.4 4区工程技术

Macromolecular Theory and Simulations Pub Date : 2023-08-18 DOI: 10.1002/mats.202300036

Han Guo, Jia Chen, Xujin Lv, Xin Qu, Baoyan Zhang, Gongqiu Peng, Yong Liu

{"title":"Mesoscopic Simulation of Centrifugal Melt Electrospinning of PPESK","authors":"Han Guo, Jia Chen, Xujin Lv, Xin Qu, Baoyan Zhang, Gongqiu Peng, Yong Liu","doi":"10.1002/mats.202300036","DOIUrl":"10.1002/mats.202300036","url":null,"abstract":"Poly(aryl ether sulfone ketone) (PPESK) is an engineering plastic with high strength, good heat resistance, insulation, and chemical corrosion resistance. The properties of PPESK fiber prepared by centrifugal melt electrospinning can be improved, and the method is efficient and environmentally friendly. This article employs a systematic analysis to investigate the impact of process parameters on the jet formation process, jet motion, fiber diameter, fiber yield, and changes in molecular chain orientation of PPESK. The analysis uses dissipative particle dynamics simulation to reveal that PPESK fibers can attain a certain degree of refinement, and fiber yield can be increased with an appropriate increase in rotational speed, temperature, and electric field force. Moreover, for PPESK with different chain lengths, longer molecular chains impede the untwisting of the molecular chains within the fiber, weakening the fiber orientation, increasing fiber diameter, and resulting in a slower fiber yield increase. These simulation results provide theoretical guidance for preparing PPESK ultrafine fibers with the required performance, shortening the exploration process of actual spinning, and saving time and labor.","PeriodicalId":18157,"journal":{"name":"Macromolecular Theory and Simulations","volume":null,"pages":null},"PeriodicalIF":1.4,"publicationDate":"2023-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"42058619","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"工程技术","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0