Computational and Theoretical Polymer Science最新文献

Computational annealing of simulated unimodal and bimodal networks 模拟单峰和双峰网络的计算退火

Computational and Theoretical Polymer Science Pub Date : 2001-12-01 DOI: 10.1016/S1089-3156(01)00019-8

P.R. von Lockette , E.M. Arruda

{"title":"Computational annealing of simulated unimodal and bimodal networks","authors":"P.R. von Lockette , E.M. Arruda","doi":"10.1016/S1089-3156(01)00019-8","DOIUrl":"10.1016/S1089-3156(01)00019-8","url":null,"abstract":"<div><p><span>A conjugate gradient Monte Carlo algorithm was used to simulate the annealing of two and three dimensional end-linked unimodal and bimodal polydimethylsiloxane networks. Equilibrium is satisfied at every crosslink during network energy minimization resulting in distinct differences in network characteristics from classical assumptions. Annealed unimodal networks were found to retain the uniformly dispersed arrangement of crosslinks generated during the crosslinking algorithm. </span>Radial distribution functions of chain vector lengths for various unimodal systems show a shift in the mean chain length from the rms length prior to annealing to shorter lengths upon annealing. Short chains in bimodal networks cluster during the annealing process in agreement with experimental investigations of short chain agglomeration in the literature. This work provides the first predictions of bimodal chain network clustering via simulated network formation and demonstrates the critical role of network annealing in determining the initial configurations of deformable elastomeric networks. This information is extremely useful in the development of accurate constitutive models of bimodal networks.</p></div>","PeriodicalId":100309,"journal":{"name":"Computational and Theoretical Polymer Science","volume":"11 6","pages":"Pages 415-428"},"PeriodicalIF":0.0,"publicationDate":"2001-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1089-3156(01)00019-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"77818937","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 6

Monte Carlo simulations of the spatial structure of end-linked bimodal polymer networks: part II 端链双峰聚合物网络空间结构的蒙特卡罗模拟:第二部分

Computational and Theoretical Polymer Science Pub Date : 2001-12-01 DOI: 10.1016/S1089-3156(01)00008-3

W Michalke, S Kreitmeier, M Lang, A Buchner, D Göritz

{"title":"Monte Carlo simulations of the spatial structure of end-linked bimodal polymer networks: part II","authors":"W Michalke, S Kreitmeier, M Lang, A Buchner, D Göritz","doi":"10.1016/S1089-3156(01)00008-3","DOIUrl":"10.1016/S1089-3156(01)00008-3","url":null,"abstract":"<div><p>The article presents the results of Monte Carlo simulations of bimodal networks performed with the Bond-Fluctuation-Algorithm. First the sol-fractions of networks with different ratios of short chains were studied and found to be always less than 2%. Concerning clustering behaviour, we saw that while random networks always form a main cluster containing more than 95% of all chains, simulated networks with less than 80% short chains do not form a main cluster. The density profiles during the swelling process show that clustering is reflected in a lower swelling degree and a sharper transition zone between the inner part and the boundary regions of the network. Finally, comparing the density distributions of crosslinkers of unimodal and bimodal networks, we found that all unimodal networks have a more ordered structure in their interior than in the melt. On the other hand, bimodal networks, where the ratio between long and short chains leads to equal masses of the fractions, show a superposition of two separate density distribution peaks, leading to a broader distribution than the Gaussian distribution found for a melt.</p></div>","PeriodicalId":100309,"journal":{"name":"Computational and Theoretical Polymer Science","volume":"11 6","pages":"Pages 459-466"},"PeriodicalIF":0.0,"publicationDate":"2001-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1089-3156(01)00008-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87164925","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 8

Study on structure formation of short polyethylene chains via dynamic Monte Carlo simulation 聚乙烯短链结构形成的动态蒙特卡罗模拟研究

Computational and Theoretical Polymer Science Pub Date : 2001-12-01 DOI: 10.1016/S1089-3156(01)00027-7

Guoqiang Xu, Wayne L. Mattice

{"title":"Study on structure formation of short polyethylene chains via dynamic Monte Carlo simulation","authors":"Guoqiang Xu, Wayne L. Mattice","doi":"10.1016/S1089-3156(01)00027-7","DOIUrl":"10.1016/S1089-3156(01)00027-7","url":null,"abstract":"<div><p><span><span>Monte Carlo (MC) simulations of structure formation for short polyethylene chains at low temperature are performed based on a recent developed method that uses coarse-grained chains on a high coordination lattice. Local short-range interactions based on rotational isomeric state (RIS) model and long-range interactions obtained from Lennard–Jones (LJ) potential are introduced during the simulation. Properties evaluated from the simulations are the mean square dimensions, anisotropy of the </span>radius of gyration tensor, local conformation determined by the occupancy of </span><em>trans</em><span><span> state and orientation correlation functions, energy of the system, and chain packing reflected by the pair correlation functions and structure factors. All of these parameters reveal an ordering process that produces an approximation to a hexagonal crystal phase. The hexagonal structure is imposed by the presence of a diamond lattice underlying the high coordination lattice on which the simulation is performed. Folding of the chains in the crystal is mandatory, because they have fully extended lengths in excess of the dimension of the simulated periodic box. Nevertheless, the simulations demonstrate that a high degree of </span>crystallinity can be achieved in reasonable computer time. The simulation technique should be applicable to other choices of periodic boundary conditions that do not affect the results as strongly as in the present case.</span></p></div>","PeriodicalId":100309,"journal":{"name":"Computational and Theoretical Polymer Science","volume":"11 6","pages":"Pages 405-413"},"PeriodicalIF":0.0,"publicationDate":"2001-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1089-3156(01)00027-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81691785","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 18

Phase separation and gelation of polymer-dispersed liquid crystals 聚合物分散液晶的相分离和凝胶化

Computational and Theoretical Polymer Science Pub Date : 2001-12-01 DOI: 10.1016/S1089-3156(01)00030-7

H Nakazawa , S Fujinami , M Motoyama , T Ohta , T Araki , H Tanaka , T Fujisawa , H Nakada , M Hayashi , M Aizawa

引用次数: 23

Self-assembled structures of block copolymers in selective solvents reproduced by lattice Monte Carlo simulation 选择性溶剂中嵌段共聚物的自组装结构用晶格蒙特卡罗模拟再现

Computational and Theoretical Polymer Science Pub Date : 2001-12-01 DOI: 10.1016/S1089-3156(00)00025-8

J Ding , T.J Carver, A.H Windle

{"title":"Self-assembled structures of block copolymers in selective solvents reproduced by lattice Monte Carlo simulation","authors":"J Ding , T.J Carver, A.H Windle","doi":"10.1016/S1089-3156(00)00025-8","DOIUrl":"10.1016/S1089-3156(00)00025-8","url":null,"abstract":"<div><p>A lattice Monte Carlo (MC) simulation was applied to the study of block copolymers<span> in selective solvent or amphiphilic surfactant<span> solution on the segment level, hydrodynamic interactions being neglected. The code was found to be very efficient, employing a partial reptation mode as the elementary movement of the self-avoiding lattice chains. Typical self-assembled structures of block copolymers such as micelle, lamellae, hexagonal cylinder and bicontinuous networks have been successfully reproduced without any priori specification of structure. Order–disorder and order–order transitions of diblock copolymers are systematically studied by adjusting the temperature, the concentration or the block length ratio in a series computer simulations. The structural differences between micelles composed of ABA and BAB triblock copolymers are also explicitly revealed by direct visualisation of the underlying chain configurations. The simulation results are consistent with the experimental observations in the literature. This simulation approach is thus a very useful tool in the extensive investigation of self-assembled structures. It has the advantage that both micro-domains and chain configurations can be studied with only a comparatively modest call on computational resources.</span></span></p></div>","PeriodicalId":100309,"journal":{"name":"Computational and Theoretical Polymer Science","volume":"11 6","pages":"Pages 483-490"},"PeriodicalIF":0.0,"publicationDate":"2001-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1089-3156(00)00025-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88722093","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 24

Drawing of annular liquid jets at low Reynolds numbers 低雷诺数下环形液体射流的绘制

Computational and Theoretical Polymer Science Pub Date : 2001-12-01 DOI: 10.1016/S1089-3156(01)00016-2

J.I Ramos

{"title":"Drawing of annular liquid jets at low Reynolds numbers","authors":"J.I Ramos","doi":"10.1016/S1089-3156(01)00016-2","DOIUrl":"10.1016/S1089-3156(01)00016-2","url":null,"abstract":"<div><p><span>Asymptotic methods based on the slenderness ratio are used to obtain the leading-order equations that govern the fluid dynamics of axisymmetric, isothermal, Newtonian, annular liquid jets such as those employed in the manufacture of textile fibres, annular membranes, composite fibres and optical fibres, at low Reynolds numbers. It is shown that the leading-order equations are one-dimensional, and analytical solutions are obtained for steady flows at zero Reynolds numbers, zero gravitational pull, and inertialess jets. A linear stability analysis of the </span>viscous flow<span> regime indicates that the stability of annular jets is governed by the same eigenvalue equation as that for the spinning of round fibres. Numerical studies of the time-dependent equations subject to axial velocity perturbations at the nozzle exit and/or the take-up point indicate that the annular jet dynamics evolves from periodic to chaotic motions as the extension or draw ratio is increased. The power spectrum of the annular jet's radius at the take-up point broadens and the phase diagrams exhibit holes at large draw ratios. The number of holes increases as the draw ratio is increased, thus indicating the presence of strange attractors and chaotic motions.</span></p></div>","PeriodicalId":100309,"journal":{"name":"Computational and Theoretical Polymer Science","volume":"11 6","pages":"Pages 429-443"},"PeriodicalIF":0.0,"publicationDate":"2001-12-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1089-3156(01)00016-2","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87665887","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 9

Prediction of the swelling behaviour of amphiphilic hydrogels and the determination of average molecular weight between cross-links 两亲性水凝胶膨胀行为的预测及交联间平均分子量的测定

Computational and Theoretical Polymer Science Pub Date : 2001-12-01 DOI: 10.1016/S1089-3156(00)00030-1

M Şen, O Güven

引用次数: 9

New force-field parameters for use in molecular simulations of s-triazine and cyanurate-containing systems. 1 — derivation and molecular structure synopsis 用于含s-三嗪和氰尿酸盐体系分子模拟的新力场参数。1 -衍生物及分子结构概述

Computational and Theoretical Polymer Science Pub Date : 2001-12-01 DOI: 10.1016/S1089-3156(01)00009-5

R.D Allington , D Attwood , I Hamerton , J.N Hay , B.J Howlin

引用次数: 8

Strategies for multiscale modeling and simulation of organic materials: polymers and biopolymers 有机材料的多尺度建模和模拟策略:聚合物和生物聚合物

Computational and Theoretical Polymer Science Pub Date : 2001-10-01 DOI: 10.1016/S1089-3156(01)00025-3

William A Goddard III, Tahir Cagin, Mario Blanco, Nagarajan Vaidehi, Siddharth Dasgupta, Wely Floriano, Michael Belmares, Jeremy Kua, Georgios Zamanakos, Seichi Kashihara, Mihail Iotov, Guanghua Gao

{"title":"Strategies for multiscale modeling and simulation of organic materials: polymers and biopolymers","authors":"William A Goddard III, Tahir Cagin, Mario Blanco, Nagarajan Vaidehi, Siddharth Dasgupta, Wely Floriano, Michael Belmares, Jeremy Kua, Georgios Zamanakos, Seichi Kashihara, Mihail Iotov, Guanghua Gao","doi":"10.1016/S1089-3156(01)00025-3","DOIUrl":"10.1016/S1089-3156(01)00025-3","url":null,"abstract":"<div><p><span>Advances in theory and methods are making it practical to consider fully first principles (de novo) predictions of structures, properties and processes for organic materials. However, despite the progress there remains an enormous challenge in bridging the vast range of distances and time scales between de novo atomistic simulations<span><span> and the quantitative continuum models for the macroscopic systems essential in industrial design and operations. Recent advances relevant to such developments include: quantum chemistry including continuum </span>solvation<span> and force field embedding, de novo force fields to describe phase transitions, molecular dynamics (MD) including continuum solvent, non equilibrium<span> MD for rheology and thermal conductivity and mesoscale simulations. To provide some flavor for the opportunities we will illustrate some of the progress and challenges by summarizing some recent developments in methods and their applications to polymers and </span></span></span></span>biopolymers<span>. Four different topics will be covered: (1) hierarchical modeling approach applied to modeling olfactory receptors, (2) stabilization of leucine zipper coils by introduction of trifluoroleucine, (3) modeling response of polymers sensors for electronic nose, and (4) diffusion of gases in amorphous polymers.</span></p></div>","PeriodicalId":100309,"journal":{"name":"Computational and Theoretical Polymer Science","volume":"11 5","pages":"Pages 329-343"},"PeriodicalIF":0.0,"publicationDate":"2001-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1089-3156(01)00025-3","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"73336156","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 42

Molecular dynamics calculation to clarify the relationship between structure and mechanical properties of polymer crystals: the case of orthorhombic polyethylene 分子动力学计算阐明聚合物晶体结构与力学性能之间的关系:以正交聚乙烯为例

Computational and Theoretical Polymer Science Pub Date : 2001-10-01 DOI: 10.1016/S1089-3156(01)00005-8

K. Tashiro

{"title":"Molecular dynamics calculation to clarify the relationship between structure and mechanical properties of polymer crystals: the case of orthorhombic polyethylene","authors":"K. Tashiro","doi":"10.1016/S1089-3156(01)00005-8","DOIUrl":"10.1016/S1089-3156(01)00005-8","url":null,"abstract":"<div><p>The molecular dynamics (MD) technique was used to calculate the temperature dependence of the structure, molecular motion, and mechanical property of the orthorhombic polyethylene (PE) crystal. The potential functional parameters reported by Karasawa et al. (J Phys Chem, 95 (1991) 2260) were refined further so that the vibrational frequencies of infrared and Raman bands, measured by us at ultra-low temperatures for the normal and fully deuterated PE, could be reproduced well. The flip-flop motion around the chain axis and the torsional motion of the skeletal chains were found to start above ca. 350K and increase the amplitude of these motions progressively. Coupling these two types of chain motion resulted in a steep increase of the thermal vibration parameters or the mean-square-displacements of carbon and hydrogen atoms, corresponding well with the X-ray data. The lattice constants and the related linear thermal expansion coefficients were also found to be in good agreement with the observed data. The calculated Young's modulus along the chain axis decreased gradually with the increasing temperature: 330GPa at 0K to 280GPa at room temperature. The latter was in good agreement with the value of 280–305GPa evaluated from the Raman measurement of the longitudinal acoustic mode. Young's modulus was found to relate intimately with the chain contraction caused by the skeletal torsional motion. Only 0.3% contraction of the chain resulted in the reduction of the modulus by ca. 35%. A similar behavior was also seen in the trigonal polyoxymethylene and nylon 6 α forms.</p></div>","PeriodicalId":100309,"journal":{"name":"Computational and Theoretical Polymer Science","volume":"11 5","pages":"Pages 357-374"},"PeriodicalIF":0.0,"publicationDate":"2001-10-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1089-3156(01)00005-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83749508","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 21