Conformational properties and dynamics of molecular bottle-brushes: A cellular-automaton-based simulation

Khalatur, Pavel G.; Shirvanyanz, David G.; Starovoitova, N. Yu.; Khokhlov, Alexei R.

doi:10.1002/(sici)1521-3919(20000301)9:3<141::aid-mats141>3.0.co;2-3

Cited by 49 publications

(71 citation statements)

References 31 publications

(77 reference statements)

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“…[7] But not only that, in some cases it may also lead to bending and twisting resulting in spiral-like conformations. Such structures were observed experimentally and by computer simulations [11,12] and are described theoretically in ref. [13] Comb copolymers with attractive interaction between the side chains (e. g., molecules consisting of hydrophobic side chains and a hydrophilic backbone in water) are currently a subject of much interest.…”

Section: Introductionsupporting

confidence: 89%

Microphase Separation within a Comb Copolymer with Attractive Side Chains: A Computer Simulation Study

Vasilevskaya¹,

Klochkov

Khalatur

et al. 2001

Macromol. Theory Simul.

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Computer simulation modelling of a flexible comb copolymer with attractive interactions between the monomer units of the side chains is performed. The conditions for the coil‐globule transition, induced by the increase of attractive interaction, ε, between side chain monomer units, are analysed for different values of the number of monomer units in the backbone, N, in the side chains, n, and between successive grafting points, m. It is shown that the coil‐globule transition of such a copolymer corresponds to a first‐order phase transition. The energy of attraction (ε) required for the realisation of the coil‐globule transition decreases with increasing n and decreasing m. The coil‐globule transition is accompanied by significant aggregation of side chain units. The resulting globule has a complex structure. In the case of a relatively short backbone (small value of N), the globule consists of a spherical core formed by side chains and an enveloping shell formed by the monomer units of the backbone. In the case of long copolymers (large value of N), the side chains form several spherical micelles while the backbone is wrapped on the surfaces of these micelles and between them.

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Section: Introductionsupporting

confidence: 89%

Microphase Separation within a Comb Copolymer with Attractive Side Chains: A Computer Simulation Study

Vasilevskaya¹,

Klochkov

Khalatur

et al. 2001

Macromol. Theory Simul.

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“…Therefore, it has recently been shown that the persistence length depends not onlyon the backbone length [19,20], but on the solvent conditions as well [15]. Although there exist many experimental and theoretical studies for the linear d imensions of these macro molecules in various solvents [3,4,19,[21][22][23][24][25][26][27][28][29][30][31][32][33][34][35][36],there are very few systematic studies of this problem [15], wherethe power laws and the associated effective exponents have been with a Flexible Backbone under Theta and Good Solvent Conditions discussed.It has been shown that for bottle brushes with a flexib le backbone evenat the theta point the side chains are considerably stretched,their linear dimension depending on the solvent quality only weakly, whilethe dependence of the persistence length on backbone length and temperature has alsobeen discussed [15].…”

Section: Introductionmentioning

confidence: 60%

Molecular Dynamics Simulations of Bottle-Brush Polymers with a Flexible Backbone under Theta and Good Solvent Conditions

Theodorakis¹,

Fytas²

2012

AJCMP

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Even at temperatures T close to the theta point the side chains are significantly stretched, as it has been confirmed for bottle brushes with a rigid backbone, their linear dimension depending on the solvent quality only weakly. Ho wever, the distribution of monomers shows a more pronounced dependence, which we characterize through the asphericity and acylindricity as functions of σ, T, N b , and N. In part icular, increase of σ, T, N b , and N increases the normalized asphericity and acylindricity of the macro molecule. Interestingly, we also find that the dimensions of the side chains reveals differences in the distributions of side chain monomers by changing the backbone length N b as the region between the two backbone-ends increases. A method to ext ract the persistence length of bottle-brush macromo lecules and its drawbacks is also discussed given that different measures of the persistence length are not mutually consistent with each other and depend distinctly both on N b and the solvent quality.

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“…According to Khoklov et al, 87,88 the LMD approach is capable of yielding convergence to limiting distribution functions nearly an order of magnitude faster than typical MC lattice-based simulations of polymers. The coarsegrained representation of Nafion used was identical to that employed in the earlier MC/RISM work by Khalatur et al, 77 and systems of 30 or 240 macromolecules were simulated on a three-dimensional simple cubic lattice using differing water contents at close to realistic densities for hydrated membranes, ca.…”

Section: Mesoscale Modelsmentioning

confidence: 99%

Modelling of morphology and proton transport in PFSA membranes

Elliott

Paddison

2007

Phys. Chem. Chem. Phys.

226

255

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Computational modelling studies of the structure of perfluorosulfonic acid (PFSA) ionomer membranes consistently exhibit a nanoscopic phase-separated morphology in which the ionic side chains and aqueous counterions segregate from the fluorocarbon backbone to form clusters or channels. Although these investigations do not unambiguously predict the size or shape of the clusters, and whether or not the channels percolate the matrix or if the connections between them are more transient, the sequence of co-monomers along the main chain appears strongly to influence the domain size of the ionic regions, with more blocky sequences giving rise to larger domain sizes. The fundamental insight that substantial rearrangement of the sulfonic acid terminated side chains and fluorocarbon backbone takes place during swelling or shrinkage is borne out by both molecular and mesoscale simulations of model PFSA polymers, along with ab initio electronic structure calculations of minimally hydrated oligomeric fragments. Molecularlevel modelling of proton transport in PFSA membranes attests to the complexity of the underlying mechanisms and the need to examine the chemical and physical processes at several distinct time and length scales. These investigations have revealed that the conformation of the fluorocarbon backbone, flexibility of the sidechains, and degree of aggregation and association of the sulfonic acid groups under minimally hydrated conditions collectively control the dissociation of the protons and the formation of Zundel and Eigen cations. The former appear to be the dominant charge carriers when the limiting water content allows only for the formation of a contact ion pair with the tethered sulfonate anion. As the water content increases, solventseparated Eigen ions begin to appear, indicating that the dominant mechanism for diffusion of protons occurs over a region approximately 4 Å away from the sulfonate groups. Finally, both the vehicular and Grotthuss shuttling mechanisms contribute to the mobility of the protons but, surprisingly, they are not always correlated, resulting in a lower overall diffusion coefficient. In summary, as the preceding observations indicate, the state of computational modelling of PFSA membranes has progressed sufficiently over the last decade to enable its use as a powerful predictive tool with which to guide the process of designing novel membrane materials for fuel cell applications.

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Conformational properties and dynamics of molecular bottle-brushes: A cellular-automaton-based simulation

Cited by 49 publications

References 31 publications

Microphase Separation within a Comb Copolymer with Attractive Side Chains: A Computer Simulation Study

Microphase Separation within a Comb Copolymer with Attractive Side Chains: A Computer Simulation Study

Molecular Dynamics Simulations of Bottle-Brush Polymers with a Flexible Backbone under Theta and Good Solvent Conditions

Modelling of morphology and proton transport in PFSA membranes

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