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Die Makromolekulare Chemie, Theory and Simulations最新文献

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Collapse of a polymer gel induced by complex formation with linear polymers 由线性聚合物形成的络合物引起的聚合物凝胶的坍塌
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1993-03-01 DOI: 10.1002/MATS.1993.040020202
A. Khokhlov, E. Kramarenko
{"title":"Collapse of a polymer gel induced by complex formation with linear polymers","authors":"A. Khokhlov, E. Kramarenko","doi":"10.1002/MATS.1993.040020202","DOIUrl":"https://doi.org/10.1002/MATS.1993.040020202","url":null,"abstract":"The thermodynamic theory of swelling and collapse of networks in the solution of linear polymers capable to form complexes with the network chains has been developed. The interaction of components is taken into account in the framework of the Flory-Huggins approximation. It was shown that complex formation in most of the cases leads to the contraction of the network, which can be either continuous or discrete. The influence of the solvent quality for the network and for the complex on the behavior of the network has been studied. If the solvent is poor for complexes the network reswells at high concentration of linear chains in the outer solution. This reswelling is realized as a steep conformation transition.","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125404710","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
Stress tensor in model polymer systems with periodic boundaries 具有周期边界的模型聚合物体系的应力张量
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1993-03-01 DOI: 10.1002/MATS.1993.040020204
D. Theodorou, T. Boone, L. Dodd, K. Mansfield
{"title":"Stress tensor in model polymer systems with periodic boundaries","authors":"D. Theodorou, T. Boone, L. Dodd, K. Mansfield","doi":"10.1002/MATS.1993.040020204","DOIUrl":"https://doi.org/10.1002/MATS.1993.040020204","url":null,"abstract":"The calculation of the stress tensor from molecular simulations of atomistic model polymer systems employing periodic boundary conditions is discussed. Starting from the dynamical equations governing the motion of sites, correct double summation forms of the atomic and the molecular virial equations are derived, which are valid for flexible, infinitely stiff and rigid chain models even in the presence of interactions between different images of the same parent macromolecule. A new expression for the true instantaneous stress (flux of momentum through the faces of the simulation box) is derived and shown to exhibit large fluctuations when applied in molecular dynamics simulations. A new equation for the thermodynamic stress, cast exclusively in terms of intermolecular forces on interaction sites, is also derived. Application to Monte Carlo simulations shows that the molecular virial expression exhibits the smallest fluctuations among all stress expressions discussed, and thus allows computation of the thermodynamic stress with least uncertainty. A scheme is developed for the calculation of surface tension from intermolecular forces only.","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"51 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1993-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126811888","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: 47
Conformation of 4-ethoxy-4′-biphenylyl cyanide in the isotropic and anisotropic liquid-crystalline state — a rotational isomeric state simulation of 2H NMR spectra 4-乙氧基-4′-联苯氰化物在各向同性和各向异性液晶状态下的构象——2H核磁共振光谱的旋转异构态模拟
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1992-11-01 DOI: 10.1002/MATS.1992.040010606
A. Abe, N. Kimura, Mamoru Nakamura
{"title":"Conformation of 4-ethoxy-4′-biphenylyl cyanide in the isotropic and anisotropic liquid-crystalline state — a rotational isomeric state simulation of 2H NMR spectra","authors":"A. Abe, N. Kimura, Mamoru Nakamura","doi":"10.1002/MATS.1992.040010606","DOIUrl":"https://doi.org/10.1002/MATS.1992.040010606","url":null,"abstract":"The conformation of the ethoxy tail flanking the cyanobiphenyl core has been studied in the liquid-crystalline phase as well as in the isotropic solution. In solution, the vicinal coupling constant 3JCH for the moiety CphOCH (Cph: phenyl carbon) provided the information regarding the rotation around the OC bond. Phenetole was mostly used as a model compound. The conventional rotational isomeric state (RIS) analysis yielded the energy difference between the gauche and trans state to be of the order of 1,6 to 1,4 kcal/mol in CDCl3, C6D6 and dimethyl-d6 sulfoxide. In this treatment, the rotational state around the neighboring bond (CphO) was taken to occur at 0 or π. The deuterated compound, 4-ethoxy-4′-biphenylyl-d7 cyanide, was prepared and studied in the liquid-crystalline state by 2H NMR. The orientational order parameters of the mesogenic core were determined by the analysis of dipolar and quadrupolar splitting data due to aromatic deuterons. The quadrupolar splitting data were also obtained for the deuterated ethoxy tail. The conformation of the tail was elucidated according to the RIS simulation scheme previously proposed. The fraction of the trans conformation ft was estimated to be 0,79 around the nematic-isotropic transition temperature (TNI = 91,9°C). It was suggested that the conformation of the ethoxy tail remains nearly unaffected by the phase transition in the immediate vicinity of TNI. The fraction ft increases moderately toward an asymptotic value as temperature decreases.","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"178 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"119425912","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: 4
Existence of nonlinear resonances in polyethylene 聚乙烯中非线性共振的存在性
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1992-11-01 DOI: 10.1002/MATS.1992.040010602
D. W. Noid, B. Sumpter
{"title":"Existence of nonlinear resonances in polyethylene","authors":"D. W. Noid, B. Sumpter","doi":"10.1002/MATS.1992.040010602","DOIUrl":"https://doi.org/10.1002/MATS.1992.040010602","url":null,"abstract":"In this paper, we demonstrate that the internal dynamics and vibrational spectra of polyethylene are influenced by Fermi and other nonlinear resonances. In previous work, the first semiclassical theory and quantum numbers (in parabolic coordinates) appropriate for this type of resonance were developed. We find from detailed molecular dynamics simulations that the same types of quantum numbers are applicable for polyethylene stretch-bend mode interactions. In addition, a one-to-one resonance is found to exist from one local CH stretch to another CH stretch along the polymer chain.","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"88 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124566339","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
Dynamics of multicomponent polymer mixtures: theoretical models 多组分聚合物混合物动力学:理论模型
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1992-11-01 DOI: 10.1002/MATS.1992.040010601
M. Benmouna, T. Vilgis, H. Benoit
{"title":"Dynamics of multicomponent polymer mixtures: theoretical models","authors":"M. Benmouna, T. Vilgis, H. Benoit","doi":"10.1002/MATS.1992.040010601","DOIUrl":"https://doi.org/10.1002/MATS.1992.040010601","url":null,"abstract":"Theoretical models describing the dynamics of multicomponent polymer mixtures are reviewed. Some detailed derivations are shown to make the basic assumptions clear and to ease the comparison between these models. The effects of random noise and memory functions on the time evolution of dynamical correlation functions are examined. The long-range hydrodynamic interactions or mode-coupling effects are also included. A possible extension of these models to the kinetics of spinodal decomposition in solutions of polymer mixtures is briefly discussed.","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"83 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"126181350","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: 3
Conformational analysis and electronic structure calculations of S-1,2-bis(2-dibutenoyl)glycerol and S-1,2-bis(2,4-hexadienoyl)glycerol, two analogues of 1,2-bis(2,4-octadecadienoyl)-sn-glycero-3-phosphorylcholine 1,2-二(2,4-十八二烯基)-sn-甘油-3-磷胆碱的两种类似物s -1,2-二(2,4-己二烯基)甘油的构象分析和电子结构计算
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1992-09-01 DOI: 10.1002/MATS.1992.040010505
P. Faupel, V. Buss
{"title":"Conformational analysis and electronic structure calculations of S-1,2-bis(2-dibutenoyl)glycerol and S-1,2-bis(2,4-hexadienoyl)glycerol, two analogues of 1,2-bis(2,4-octadecadienoyl)-sn-glycero-3-phosphorylcholine","authors":"P. Faupel, V. Buss","doi":"10.1002/MATS.1992.040010505","DOIUrl":"https://doi.org/10.1002/MATS.1992.040010505","url":null,"abstract":"","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"36 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125325875","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
The configurational free energy of a polymer chain 聚合物链的构型自由能
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1992-09-01 DOI: 10.1002/MATS.1992.040010504
F. Ganazzoli, G. Allegra, E. Colombo, M. D. Vitis
{"title":"The configurational free energy of a polymer chain","authors":"F. Ganazzoli, G. Allegra, E. Colombo, M. D. Vitis","doi":"10.1002/MATS.1992.040010504","DOIUrl":"https://doi.org/10.1002/MATS.1992.040010504","url":null,"abstract":"The configurational, or elastic, free energy Ael of a polymer chain is discussed in terms of the Fourier configurational approach. The importance of accounting for all degrees of freedom of the chain is shown in comparison with affine mean-field theories and with scaling theories of chain expansion and contraction. In case of strong contraction the chain does show neither affinity nor self-similarity, and we get Ael ∼ N1/3, N being the number of chain bonds. Conversely, in case of good-solvent expansion we find Ael ∼ N. The same result holds in the vicinity of the Θ-temperature, where Ael is also proportional to [(T − Θ)/T]2.","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125786939","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: 3
Angular correlations within coiled polymer molecules 卷曲聚合物分子内的角相关性
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1992-09-01 DOI: 10.1002/MATS.1992.040010502
W. Bruns
{"title":"Angular correlations within coiled polymer molecules","authors":"W. Bruns","doi":"10.1002/MATS.1992.040010502","DOIUrl":"https://doi.org/10.1002/MATS.1992.040010502","url":null,"abstract":"Monte Carlo techniques were used to investigate angular correlations between the principal axes of inertia and the end-to-end vector as well as the first two normal coordinates. On the average, the first normal coordinate is nearly parallel to the longest principal axis. The parallelism is less distinct in the case of the end-to-end vector and the longest principal axis. The assumption made by some authors that the second normal coordinate is coplanar with the two longest principal axes could not be confirmed.","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"10 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127121471","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
Shear of a planar polyelectrolyte brush 平面聚电解质电刷的剪切性能
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1992-06-01 DOI: 10.1002/MATS.1992.040010401
T. M. Birshtein, E. B. Zhulina
{"title":"Shear of a planar polyelectrolyte brush","authors":"T. M. Birshtein, E. B. Zhulina","doi":"10.1002/MATS.1992.040010401","DOIUrl":"https://doi.org/10.1002/MATS.1992.040010401","url":null,"abstract":"The behavior of a planar polyelectrolyte brush subjected to normal and tangential external forces is considered. A new “polyelectrolyte effect” is predicted: shear of a free polyelectrolyte brush leads to a decrease in brush thickness contrary to the case of a free neutral brush. Such behavior is equivalent to that of a neutral brush subjected to an external normal stretching force. In the case of a polyelectrolyte brush this force is created by the osmotic pressure of mobile counterions neutralizing grafted chain charges. Addition of salt diminishes the polyelectrolyte effect and changes the sign of correlation between brush thickness and tangential deformation.","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"53 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128592406","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: 5
Liquid-crystalline ordering in two-dimensional systems with discrete symmetry 二维离散对称系统中的液晶有序
Die Makromolekulare Chemie, Theory and Simulations Pub Date : 1992-06-01 DOI: 10.1002/MATS.1992.040010402
A. Mercurieva, T. M. Birshtein
{"title":"Liquid-crystalline ordering in two-dimensional systems with discrete symmetry","authors":"A. Mercurieva, T. M. Birshtein","doi":"10.1002/MATS.1992.040010402","DOIUrl":"https://doi.org/10.1002/MATS.1992.040010402","url":null,"abstract":"The mean-field theories of liquid-crystalline (nematic) ordering developed for three-dimensional systems are applied to describe two-dimensional systems of both geometrically anisotropic and anisotropically interacting particles. Systems with discrete symmetry (lattice models) for which long-range order is possible are considered on the base of the Landau free-energy expansion. It is shown that the Hamiltonian describing the energy of intermolecular interactions may be written in a common form for lyotropic and thermotropic systems. The mean-field theory gives a continuous phase transition (second-order phase transition) for a square lattice, whereas for a triangular lattice it gives a phase transition with latent heat (first-order phase transition) like for three-dimensional systems. These results are compared with results of the exact theories (two-dimensional Ising and Potts models). It is concluded that for realistic two-dimensional models the orientational in-plane ordering is not sharper than a second-order phase transition.","PeriodicalId":227512,"journal":{"name":"Die Makromolekulare Chemie, Theory and Simulations","volume":"98 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1992-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"124685096","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: 13
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