Macromolecular Theory and Simulations

Cover image for Vol. 24 Issue 4

Early View (Online Version of Record published before inclusion in an issue)

Editor-in-Chief: Kirsten Severing, Editor: Stefan Spiegel

Online ISSN: 1521-3919

Associated Title(s): Macromolecular Chemistry and Physics, Macromolecular Materials and Engineering, Macromolecular Rapid Communications, Macromolecular Reaction Engineering

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  1. Full Papers

    1. Self-Organization of Polyurethane Pre-Polymers as Studied by Self-Consistent Field Theory

      Feng Li, Remco Tuinier, Ilse van Casteren, Ronald Tennebroek, Ad Overbeek and Frans A. M. Leermakers

      Article first published online: 2 SEP 2015 | DOI: 10.1002/mats.201400106

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      Using self-consistent field (SCF) theory with a molecularly detailed model, the authors study the self-assembly of polyurethane pre-polymer dispersions in aqueous solutions. Insight into the physical–chemical behavior of PU pre-polymer dispersions is obtained. Details like radial volume fraction distribution of six representative PU pre-polymers and water on a single swollen micelle are shown in this paper.

    2. Design of Aggregate Structures and Molecular Capture by Using Molecular-Cluster-Assembly Method

      Shirun Ho

      Article first published online: 20 AUG 2015 | DOI: 10.1002/mats.201500041

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      Aggregate structures of acrylic acid oligomers and the capability of capturing ethylene carbonates (ECs) are analyzed by molecular-cluster-assembly method. A hexamer comprised of arched oligomers captures two ECs in series inside the middle of a constricted channel. Methylene and carbonyl groups of the two ECs form hydrogen bondings and attractive interaction between them.

    3. Comparative Study on Dynamical Heterogeneity of Ring and Linear Polymers

      Xubo Ye, Zhiping Zhou, Yijing Nie, Ping Ma, Tongfan Hao, Wenming Yang and Haifeng Lu

      Article first published online: 19 AUG 2015 | DOI: 10.1002/mats.201500042

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      Ring polymer has larger local domains of blocked segments, and thus narrower distributions of segmental mobility or weaker dynamical heterogeneity. Linear polymer has end segments with high mobility, which hindered the growth of local domains of blocked segments, and therefore wider distributions of segmental mobility, namely, stronger dynamical heterogeneity.

    4. Toward a General Methodology for Modeling Diffusive-Controlled Reactions in Free Radical Polymerization

      David Victoria-Valenzuela, Jorge Herrera-Ordonez and Gabriel Luna-Barcenas

      Article first published online: 4 AUG 2015 | DOI: 10.1002/mats.201500025

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      The proposed model includes a novel methodology for describing the diffusive step of the kinetic rate coefficients, which is based on geometric considerations and application of the Einstein diffusion equation instead of the Smoluchowski equation whose applicability is questioned in this context. An explanation for the rate of polymerization behavior and the onset of auto-acceleration effect is proposed.

    5. Molecular Dynamics Simulations Investigation of Structure and Thermodynamic Properties of Symmetric Poly(styrene-block-acrylic acid) (PS-b-PAA) Micelle in Salt-Free Aqueous Solution

      Rajalakshmi Chockalingam and Upendra Natarajan

      Article first published online: 30 JUL 2015 | DOI: 10.1002/mats.201500033

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      The polystyrene-block-polyacrylic acid (PS-b-PAA) micelle in aqueous solution shows the linear increase in micelle radius and constant PS core size as a function of ionization of PAA (f) due to conformational extension of PAA blocks is in agreement with neutron scattering observations in the literature.

  2. Feature Articles

    1. Comparative Analysis of Tethered and Untethered Polymers Close to a Surface Investigated by Monte Carlo Techniques

      Stephan Eisenhaber and Gerhard Zifferer

      Article first published online: 20 JUL 2015 | DOI: 10.1002/mats.201500032

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      The paper deals with the interaction of unconstraint as well as anchored single chains and stars with energetically neutral and attractive walls representing surfaces of nanoparticles. Although simulations are based on lattice models, lattice independent results of general validity are obtained by extrapolation to infinite chain-length, at least for neutral surfaces. A new method to determine some sort of critical adsorption point is introduced.

  3. Full Papers

    1. Reactivity Ratio Estimation in Non-Linear Polymerization Models using Markov Chain Monte Carlo Techniques and an Error-In-Variables Framework

      Manoj Mathew and Thomas Duever

      Article first published online: 20 JUL 2015 | DOI: 10.1002/mats.201500017

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      Markov Chain Monte Carlo methods are applied in the estimation of reactivity ratios in various nonlinear models. An error-in-variables approach is used and the analysis shows that application of MCMC and EVM methods produce the most reliable results in nonlinear regression.

    2. Elucidating the Morphological Complexities of Linear Symmetric Triblock Polymers Confined Between Two Parallel Plates: A Self-Consistent Field Theoretic Approach

      Mouge Mohagheghi and Bamin Khomami

      Article first published online: 14 JUL 2015 | DOI: 10.1002/mats.201500038

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      Morphological transition of symmetric linear ABC triblock terpolymer melt as a function of surface interaction and film thickness, d. In the presence of strong surface interaction, a wetting layer adjacent to the walls exists and in the center of the film, stable and metastable morphologies including C||, L⊥ and PL are observed.

    3. An Extended Flory Distribution for Kinetically Controlled Step-Growth Polymerizations Perturbed by Intramolecular Reactions

      Jonny Proppe

      Article first published online: 6 JUL 2015 | DOI: 10.1002/mats.201400101

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      A refined Flory model for describing approximate molar-mass distributions obtained from irreversible step-growth polymerizations is reconsidered. It is shown that this model is a good approximation if either step growth or cyclization is predominant. Based on this insight, a probabilistic transformation of the refined model to a quantitative description is presented.

    4. Equilibrium Distribution of Semiflexible Polymer Chains between a Macroscopic Dilute Solution Phase and Small Voids of Cylindrical Shape

      Xiaoyan Wang, Meng Tang and Yanwei Wang

      Article first published online: 1 JUL 2015 | DOI: 10.1002/mats.201500029

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      Two questions are answered: (i) which size parameter correlates best with the equilibrium partition coefficients of linear semiflexible chains in the range relevant to polymer separation in GPC? (ii) For two chains with the same contour length but different persistence length in equilibrium with a cylindrical pore, which chain spends less free energy to get in.

  4. Communications

    1. Azeotropic Equilibrium Copolymerization

      Ryszard Szymanski

      Article first published online: 29 JUN 2015 | DOI: 10.1002/mats.201500034

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      Reversible copolymerization can behave azeotropically only when certain relationships, given in the paper, between the equilibrium and rate constants of homo- and cross-propagations are held. The main conditions for azeotropicity of the reversible copolymerization ensure that the compositions and microstructures of initially formed copolymer and of that at the system equilibrium are identical.

  5. Full Papers

    1. Systematic Coarse Graining of a High-Performance Polyimide

      Sudharsan Pandiyan, Priya V. Parandekar, Om Prakash, Thomas K. Tsotsis and Sumit Basu

      Article first published online: 19 JUN 2015 | DOI: 10.1002/mats.201500009

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      The figure shows three mapping schemes of molecular fragments in the backbone of the commercial polyimide HFPE-30. A coarse-grained representation with large number of beads is necessary to predict static and configurational properties. However, with smaller number of beads and an appropriate amount of friction on the beads, we are able to predict glass transition temperature and stress–strain response.

    2. Hierarchical Microstructures Self-Assembled from Linear Multiblock Copolymers in Thin Films

      Jingyuan Lin, Shuting Gong, Xu Zhang and Liquan Wang

      Article first published online: 16 JUN 2015 | DOI: 10.1002/mats.201500031

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      In thin films of linear multiblock copolymers, not only the period of large- and small-length-scale lamellae but also the orientation of small-length-scale lamellae can be tuned by varying film thickness. Moreover, a reentrant phase transition of perpendicular lamellae-in-lamellae with increasing the film thickness is revealed.

    3. Monte Carlo Simulation Studies of Regular and Irregular Dendritic Polymers

      Edyta Wawrzyńska, Andrzej Sikorski and Gerhard Zifferer

      Article first published online: 8 JUN 2015 | DOI: 10.1002/mats.201500036

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      Regular and irregular dendritic polymers, the latter realized for several types of branch-length distributions, are simulated and their properties are compared. In addition, for the regular case emphasis is given to parameters in the limit of infinite branch length (spacer length) in order to obtain model independent results.

    4. Parallel Monte Carlo Simulation of Molecular Weight Distribution and Chemical Composition Distribution for Copolymerization on a Graphics Processing Unit Platform

      Jinzu Weng, Xi Chen, Zhen Yao and Lorenz T. Biegler

      Article first published online: 3 JUN 2015 | DOI: 10.1002/mats.201500021

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      Monte Carlo method is suitable to simulate the microstructural distributions, but it normally requires a long time for the computation. By decomposing the conventional Monte Carlo simulation of all chains into millions of threads, the calculation is parallelized on a GPU platform and more than 30-fold speedup ratio is obtained.

    5. Direct Equilibration and Characterization of Polymer Melts for Computer Simulations

      Livia A. Moreira, Guojie Zhang, Franziska Müller, Torsten Stuehn and Kurt Kremer

      Article first published online: 3 JUN 2015 | DOI: 10.1002/mats.201500013

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      Excluded volume and topological constraints (entanglements) lead to difficulties for polymer melt equilibration in computer simulations. To avoid long equilibration runs, an improved feedback loop methodology is introduced, which only needs relaxation on short length scales. The analysis shows that a homogeneous density and perfect internal distances along the chain backbone can be reached for melts of chains of up to about 45 entanglement lengths.

    6. A Study of HCl Gas Adsorption/Desorption Properties of PNIPAM Brushes

      Xin Jun Zhao, Zhi Fu Gao and Zhong Ying Jiang

      Article first published online: 3 JUN 2015 | DOI: 10.1002/mats.201500027

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      HCl gas adsorption capacity of poly(N-isopropylacrylamide) (PNIPAM) brushes is described by PNIPAM–HCl hydrogen bonds. Hydrogen bonding becomes a key element in determining HCl adsorption/desorption behaviors of PNIPAM brushes. The morphology of PNIPAM brushes may have a significant effect on the HCl adsorption/desorption properties.

    7. Coarse-Grained and Atomistic Simulations for the G = 4 PAMAM-EDA Dendrimer

      Juan J. Freire, Ana M. Rubio and Carl McBride

      Article first published online: 1 JUN 2015 | DOI: 10.1002/mats.201500028

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      Extended molecular dynamics simulations for protonated and neutral G = 4 PAMAM-EDA in water permit an accurate analysis of conformational properties. The trajectories are used to compute binary interactions between dendrimer molecules. These interactions are shown to obey the theoretically predicted Gaussian behavior.

    8. Theoretical Consideration of Phase Behavior of the Products of Free-Radical Copolymerization Described by the Penultimate Model

      Semion I. Kuchanov, Artem N. Bogdanov and Konstantin V. Tarasevich

      Article first published online: 26 MAY 2015 | DOI: 10.1002/mats.201500022

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      Finding of the dependence of the phase behavior of heteropolymer liquids on the chemical structure of their macromolecules is of utmost importance. Theoretical consideration of such a behavior of multiblock copolymers whose architectures are describable by the extended Markov chain has been undertaken in this paper. Our analysis reveals the possibility of the existence in their melts of phase diagrams of nontraditional appearance.

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