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Journal ArticleDOI

Self-association behaviour of atactic polymethacrylic acid in aqueous solution investigated by atomistic molecular dynamics simulations

30 Jun 2015-Molecular Simulation (Taylor & Francis)-Vol. 41, Iss: 13, pp 1110-1121
TL;DR: In this article, the self-association behavior of atactic poly(methacrylic acid) (a-PMA) in water was investigated by atomistic molecular dynamics simulations.
Abstract: The self-association behaviour of atactic poly(methacrylic acid) (a-PMA) in water was investigated by atomistic molecular dynamics (MD) simulations. Simulations show that interchain association of a-PMA occurs only in its un-neutralised form, by hydrogen bonding between –COOH groups, which is in agreement with the experimental observation. Chain conformations, dihedral angle distributions, hydration behaviour, scattering structure factor and enthalpy-of-hydration (i.e. aqueous solvation) were analysed as a function of concentration for un-neutralised PMA, across dilute to concentrated regimes. The average 〈Rg〉 of the chain remains unaffected in solution and also for amorphous undissolved a-PMA phase, confirming the occurrence of the approximate theta-solution condition for the first time, as revealed by simulations, in a polar hydrogen-bonding polymer aqueous solution. Chain hydration behaviour and scattering structure factor show significant changes in concentrated regime. Scattering intensity collapse o...
Citations
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01 Jan 2016
TL;DR: The introduction to polymers is universally compatible with any devices to read and is available in the digital library an online access to it is set as public so you can get it instantly.
Abstract: Thank you very much for downloading introduction to polymers. As you may know, people have look hundreds times for their favorite readings like this introduction to polymers, but end up in infectious downloads. Rather than reading a good book with a cup of coffee in the afternoon, instead they are facing with some infectious virus inside their desktop computer. introduction to polymers is available in our digital library an online access to it is set as public so you can get it instantly. Our digital library saves in multiple countries, allowing you to get the most less latency time to download any of our books like this one. Kindly say, the introduction to polymers is universally compatible with any devices to read.

212 citations

Journal ArticleDOI
07 Apr 2017-Polymer
TL;DR: In this paper, the authors have performed molecular dynamics simulations of aqueous solutions of a weak, pH-responsive polyelectrolyte, polyacrylic acid (PAA) with water molecules.

24 citations

Journal ArticleDOI
TL;DR: Constant pH molecular dynamics computer simulations of poly(methacrylic acid) reveal that there are two types of structural changes, one local and one global, which make up the overall response.
Abstract: Polyacidic polymers can change structure over a narrow range of pH in a competition between the hydrophobic effect, which favors a compact state, and electrostatic repulsion, which favors an extended state. Constant pH molecular dynamics computer simulations of poly(methacrylic acid) reveal that there are two types of structural changes, one local and one global, which make up the overall response. The local structural response depends on the tacticity of the polymer and leads to different cooperative effects for polymers with different stereochemistries, demonstrating both positive and negative cooperativities.

19 citations

Journal ArticleDOI
TL;DR: A model for carboxylic acids, in both the protonated and deprotonated states, is developed in which hydrogen interaction sites are not used and all interactions are short-ranged, which is able to reproduce the structural changes induced by pH.
Abstract: A model for carboxylic acids, in both the protonated and deprotonated states, is developed in which hydrogen interaction sites are not used and all interactions are short-ranged. A method for const...

11 citations

Journal ArticleDOI
TL;DR: In this paper, structural and dynamic properties of aqueous solution of atactic poly(acrylic) acid in dilute, semi-dilute and concentrated regimes were studied by fully atomistic molecular dynamics simulati...
Abstract: Structural and dynamic properties of aqueous solution of atactic poly(acrylic) acid (PAA) in dilute, semi-dilute and concentrated regimes were studied by fully atomistic molecular dynamics simulati...

9 citations

References
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Journal ArticleDOI
TL;DR: In this paper, a method is described to realize coupling to an external bath with constant temperature or pressure with adjustable time constants for the coupling, which can be easily extendable to other variables and to gradients, and can be applied also to polyatomic molecules involving internal constraints.
Abstract: In molecular dynamics (MD) simulations the need often arises to maintain such parameters as temperature or pressure rather than energy and volume, or to impose gradients for studying transport properties in nonequilibrium MD A method is described to realize coupling to an external bath with constant temperature or pressure with adjustable time constants for the coupling The method is easily extendable to other variables and to gradients, and can be applied also to polyatomic molecules involving internal constraints The influence of coupling time constants on dynamical variables is evaluated A leap‐frog algorithm is presented for the general case involving constraints with coupling to both a constant temperature and a constant pressure bath

25,256 citations

Journal ArticleDOI
TL;DR: An N⋅log(N) method for evaluating electrostatic energies and forces of large periodic systems is presented based on interpolation of the reciprocal space Ewald sums and evaluation of the resulting convolutions using fast Fourier transforms.
Abstract: An N⋅log(N) method for evaluating electrostatic energies and forces of large periodic systems is presented. The method is based on interpolation of the reciprocal space Ewald sums and evaluation of the resulting convolutions using fast Fourier transforms. Timings and accuracies are presented for three large crystalline ionic systems.

24,332 citations


"Self-association behaviour of atact..." refers methods in this paper

  • ...Particle-mesh Ewald method was used for the calculation of electrostatic potential with Fourier spacing [12,13] of 0....

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Journal ArticleDOI
TL;DR: It is demonstrated that arbitrary accuracy can be achieved, independent of system size N, at a cost that scales as N log(N), which is comparable to that of a simple truncation method of 10 A or less.
Abstract: The previously developed particle mesh Ewald method is reformulated in terms of efficient B‐spline interpolation of the structure factors This reformulation allows a natural extension of the method to potentials of the form 1/rp with p≥1 Furthermore, efficient calculation of the virial tensor follows Use of B‐splines in place of Lagrange interpolation leads to analytic gradients as well as a significant improvement in the accuracy We demonstrate that arbitrary accuracy can be achieved, independent of system size N, at a cost that scales as N log(N) For biomolecular systems with many thousands of atoms this method permits the use of Ewald summation at a computational cost comparable to that of a simple truncation method of 10 A or less

17,897 citations


"Self-association behaviour of atact..." refers methods in this paper

  • ...Particle-mesh Ewald method was used for the calculation of electrostatic potential with Fourier spacing [12,13] of 0....

    [...]

Journal ArticleDOI
TL;DR: Although the derivation of the algorithm is presented in terms of matrices, no matrix matrix multiplications are needed and only the nonzero matrix elements have to be stored, making the method useful for very large molecules.
Abstract: In this article, we present a new LINear Constraint Solver (LINCS) for molecular simulations with bond constraints. The algorithm is inherently stable, as the constraints themselves are reset instead of derivatives of the constraints, thereby eliminating drift. Although the derivation of the algorithm is presented in terms of matrices, no matrix matrix multiplications are needed and only the nonzero matrix elements have to be stored, making the method useful for very large molecules. At the same accuracy, the LINCS algorithm is three to four times faster than the SHAKE algorithm. Parallelization of the algorithm is straightforward. (C) 1997 John Wiley & Sons, Inc.

12,699 citations

Journal ArticleDOI
TL;DR: On the other hand, in this paper, a superparamagnetically collapsed Mossbauer spectrum is obtained for carbon with fewer active sites, and these particles sinter and carburize in a manner more similar to that of Fe particles supported on graphite.
Abstract: on carbon. These particles can interact with the active sites of the carbon to form a species a t the metal-carbon interface which is stable against high-temperature reduction. This interaction may occur via oxygen atoms bonding with both the carbon surface and iron atoms contacting the carbon. This oxygen could be provided by dissociation of the C O ligands during decomposition. The remainder of the surface Fe can exist in either a reduced or carburized state, but the small size of these particles results in either case in a superparamagnetically collapsed Mossbauer spectrum. For carbons with fewer active sites, more of the particles are unbound, and these particles sinter and carburize in a manner more similar to that of Fe particles supported on graphite.

11,221 citations


Additional excerpts

  • ...7 KJ/mol in agreement with the value at 300K as reported in the literature.[32] Figure 10 shows the variation of the simulated hydration enthalpy of the entire solution (DHT) as well as those specifically contributed by electrostatic interactions, between all species (DHel,T), dispersive (van der Waals) interactions in the whole solution (DHd,T) and in particular polymer conformational changes (i....

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