Computational and Theoretical Polymer Science最新文献_第5页

Internal coordinate phase space analysis of macromolecular systems 大分子体系的内坐标相空间分析

Computational and Theoretical Polymer Science Pub Date : 2001-01-01 DOI: 10.1016/S1089-3156(99)00069-0

A.K. Mazur , B.G. Sumpter , D.W. Noid

{"title":"Internal coordinate phase space analysis of macromolecular systems","authors":"A.K. Mazur , B.G. Sumpter , D.W. Noid","doi":"10.1016/S1089-3156(99)00069-0","DOIUrl":"10.1016/S1089-3156(99)00069-0","url":null,"abstract":"<div>In recent studies, as well as the results presented herein, it has been shown that the classical dynamics of macromolecular systems exhibit chaos far below the zero-point energy consequently resulting in the loss of a qualitative correspondence to quantum behavior. Mechanisms responsible for this undesirable and unrealistic dynamics have been shown to be due to the flow of energy out of the high frequency modes into the low frequency, large amplitude modes. A very powerful tool for eliminating the high frequency modes in macromolecular systems has been the development of internal coordinate molecular dynamics. This method only integrates the chosen degrees of freedom that determine the overall structure of the molecular system (the torsion). In this paper, we have used this technique with the appropriate analysis from semi-classical theory and nonlinear dynamics to study the trajectories generated for some simple polymer fragments. The method does effectively eliminate most of the problems associated with zero-point energy flow and the resulting phase space structure exhibits a high degree of stable quasiperiodic motion. However, the semi-classical relationships to quantum mechanics in this quasiperiodic regime require that initial conditions be chosen carefully in order for the resulting trajectory to have any quantum relevance.</div>","PeriodicalId":100309,"journal":{"name":"Computational and Theoretical Polymer Science","volume":"11 1","pages":"Pages 35-47"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1089-3156(99)00069-0","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"82736162","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: 1

A Monte Carlo lattice model for chain diffusion in dense polymer systems and its interlocking with molecular dynamics simulation 密集聚合物体系中链式扩散及其互锁的蒙特卡罗晶格模型与分子动力学模拟

Computational and Theoretical Polymer Science Pub Date : 2001-01-01 DOI: 10.1016/S1089-3156(99)00074-4

K.R. Haire, T.J. Carver, A.H. Windle

{"title":"A Monte Carlo lattice model for chain diffusion in dense polymer systems and its interlocking with molecular dynamics simulation","authors":"K.R. Haire, T.J. Carver, A.H. Windle","doi":"10.1016/S1089-3156(99)00074-4","DOIUrl":"10.1016/S1089-3156(99)00074-4","url":null,"abstract":"<div>The paper reports the development of a Monte Carlo lattice model (cubic F) of polymer chains which is able to access times where the diffusion of the centre-of-mass of the chains is the dominant process, even though the chain lengths are well above that for entanglement. The volume of the model is large when compared with the volume of gyration of the individual molecules. The model incorporates an algorithm, which allows for the possibility of co-operative motions over sections of the chains and increases the time efficiency of the simulation. Both the model and the modifying algorithm have been tested against the known scaling laws.The model, for shorter chains, is ‘reverse mapped’ into full atomic detail as polyethylene and the shorter time processes simulated using molecular dynamics (MD). The MD model is tested against experimental diffusion data for polyethylene, of the same molecular weight and at the same temperature, and then used to time-calibrate the lattice model.Both the fine grained MD model and the coarse grained MC model are thus interlocked to cover a time range from the individual atomic motions of MD up to the order of a microsecond, a range of six orders of magnitude.</div>","PeriodicalId":100309,"journal":{"name":"Computational and Theoretical Polymer Science","volume":"11 1","pages":"Pages 17-28"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1089-3156(99)00074-4","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"75668992","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: 39

Solubility of water in polymers—atomistic simulations 水在聚合物中的溶解度——原子模拟

Computational and Theoretical Polymer Science Pub Date : 2001-01-01 DOI: 10.1016/S1089-3156(99)00061-6

B. Nick , U.W. Suter

引用次数: 22

A transport model for swelling of polyelectrolyte gels in simple and complex geometries 聚电解质凝胶在简单和复杂几何结构中的溶胀输运模型

Computational and Theoretical Polymer Science Pub Date : 2001-01-01 DOI: 10.1016/S1089-3156(99)00060-4

E.C. Achilleos , K.N. Christodoulou , I.G. Kevrekidis

引用次数: 47

Modelling the molecular weight distribution in terpolymerization systems with donor–acceptor complexes 具有供体-受体配合物的三元聚合体系中分子量分布的建模

Computational and Theoretical Polymer Science Pub Date : 2001-01-01 DOI: 10.1016/S1089-3156(99)00076-8

P. Rivero , E. Etchechury

引用次数: 8

Bush region in the propagation of electrical degradation in polymers 布什区在聚合物中传播电降解

Computational and Theoretical Polymer Science Pub Date : 2001-01-01 DOI: 10.1016/S1089-3156(99)00075-6

O.P. Poznansky

引用次数: 7

Simulation of the specific interactions between polyamide-6 and a thermoplastic polyurethane 聚酰胺-6与热塑性聚氨酯之间特定相互作用的模拟

Computational and Theoretical Polymer Science Pub Date : 2001-01-01 DOI: 10.1016/S1089-3156(99)00059-8

A Genovese, R.A Shanks

{"title":"Simulation of the specific interactions between polyamide-6 and a thermoplastic polyurethane","authors":"A Genovese, R.A Shanks","doi":"10.1016/S1089-3156(99)00059-8","DOIUrl":"10.1016/S1089-3156(99)00059-8","url":null,"abstract":"<div>Polyamides have many desirable properties such as high melting temperatures, chemical resistance and superior mechanical properties. However, its crystalline morphology can limit its applications. It is the specific interaction, hydrogen bonding that gives rise to the crystalline structure of polyamides. This interaction is strong and important when blending on the final morphology and mechanical properties. Polyurethane contains polar functionality that can also interact with the polar component of polyamide. Hence, it is important to study the interaction between such a blend as polyurethane can enhance the toughness of polyamide due to its elastic properties. This study is an insight into the specific interaction between two polar polymers in a simulation whereby the interaction is maximised. Hydrogen bonding has been observed between molecules of either polyamide–polyurethane and polyamide–polyamide, and it is sufficiently strong to cause the polymer chains to distort rather than disrupt the hydrogen bonds. When groups of like polarity, such as carbonyl groups, come into proximity, the polymer chains again distort from their regular conformation because of mutual repulsion.</div>","PeriodicalId":100309,"journal":{"name":"Computational and Theoretical Polymer Science","volume":"11 1","pages":"Pages 57-62"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1089-3156(99)00059-8","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84979587","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: 28

Glass transition temperature of poly(vinylchloride) from molecular dynamics simulation: explicit atom model versus rigid CH2 and CHCl groups model 分子动力学模拟的聚氯乙烯玻璃化转变温度:显式原子模型与刚性CH2和CHCl基模型

Computational and Theoretical Polymer Science Pub Date : 2001-01-01 DOI: 10.1016/S1089-3156(99)00070-7

B.F Abu-Sharkh

{"title":"Glass transition temperature of poly(vinylchloride) from molecular dynamics simulation: explicit atom model versus rigid CH2 and CHCl groups model","authors":"B.F Abu-Sharkh","doi":"10.1016/S1089-3156(99)00070-7","DOIUrl":"10.1016/S1089-3156(99)00070-7","url":null,"abstract":"<div>Glass transition temperature is the most important descriptor of the properties of amorphous polymers. In this study, molecular dynamics (MD) simulation is used to generate volume-temperature (VT) data at constant pressure for poly(vinylchloride) (PVC) over a temperature range that includes the experimental glass transition temperature (Tg) to study the validity of MD simulation in predicting Tg of amorphous polar polymers. PVC contains a polar group (chloride) which induces a partial charge distribution on all atomic sites of the polymer repeat unit. Two types of MD simulation were conducted. In the first type, all atomic sites were explicitly represented in the polymer chain model. In the second type of simulation, the CH2 and CHCl groups were modeled as rigid units to minimize the computational effort. The Tg values obtained from the MD VT curves were slightly displaced upward relative to the experimental Tg. The rigid unit model tends to under estimate the liquid density compared with the explicit atom model. MD simulation seems to be a practical procedure for predicting the Tg of polar polymers. The rigid unit model provides substantial saving in the computational effort without loss of accuracy.</div>","PeriodicalId":100309,"journal":{"name":"Computational and Theoretical Polymer Science","volume":"11 1","pages":"Pages 29-34"},"PeriodicalIF":0.0,"publicationDate":"2001-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1089-3156(99)00070-7","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"87171972","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: 37

Chain statistics and heat of reaction in random copolymerization 无规共聚的链统计和反应热

Computational and Theoretical Polymer Science Pub Date : 2000-08-18 DOI: 10.1016/S1089-3156(99)00058-6

J. Dayantis

引用次数: 0

A generalized method to calculate diffusion rates in polydisperse systems. Application to miscible polymer pairs in the concentrated regime 计算多分散系统中扩散速率的一种广义方法。浓态下混相聚合物对的应用

Computational and Theoretical Polymer Science Pub Date : 2000-08-18 DOI: 10.1016/S1089-3156(99)00071-9

E. Pardo , J.P. Tomba , J.M. Carella

{"title":"A generalized method to calculate diffusion rates in polydisperse systems. Application to miscible polymer pairs in the concentrated regime","authors":"E. Pardo , J.P. Tomba , J.M. Carella","doi":"10.1016/S1089-3156(99)00071-9","DOIUrl":"10.1016/S1089-3156(99)00071-9","url":null,"abstract":"<div>A generalized method for calculating diffusion rates in polydisperse systems, valid in the concentrated regime, is outlined. In the formulation of the method the discrete variable that describes the molecular size, is replaced by a continuous variable in the same range. This replacement diminishes the number of degrees of freedom but keeping the essential physics of the original statement. The effects of monomeric friction coefficient, Flory-Huggins thermodynamic interaction parameter, individual species molecular weights, local molecular weights distribution and local Tg are consistently included in the model.The method is used to calculate concentration distribution profiles generated by diffusion of polydisperse polymers blends, and experimentally tested. For this purpose polystyrene with discrete (bimodal and tetramodal) molecular weight distributions and polystyrene with wide and continuous molecular weight distributions were used to simulate polydisperse systems. They are allowed to diffuse in a blend of polyphenylene oxide and polystyrene.The simulated concentration profiles are compared with results obtained by using two experimental techniques based on independent physical properties, which give complementary information: Raman spectroscopy and DMA. The total PS concentration profiles calculated using the proposed method agree well with Raman spectroscopy results. Simulated DMA results—which are sensitive to the PS species molecular weight distribution—obtained using the concentration profiles calculated for each PS molecular weight species, agree well with the experimental DMA results. Calculations based on average molecular weights on the other hand, give incorrect results.</div>","PeriodicalId":100309,"journal":{"name":"Computational and Theoretical Polymer Science","volume":"10 6","pages":"Pages 523-533"},"PeriodicalIF":0.0,"publicationDate":"2000-08-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S1089-3156(99)00071-9","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"91484470","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: 2