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... the decrease of the swelling ratio for gels having a slight excess of anionic groups in ... 16 and with the experimental results obtained previously for weakly charged PA gels based on PAM ... The holes for metal ions were formed by... more
... the decrease of the swelling ratio for gels having a slight excess of anionic groups in ... 16 and with the experimental results obtained previously for weakly charged PA gels based on PAM ... The holes for metal ions were formed by an imprinting method during the synthesis of the ...
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The effect of a low-molecular-mass salt on the thermodynamic stability of stoichiometric interpolymer complexes composed of oppositely charged macromolecules with different solvent affinities has been theoretically studied. It has been... more
The effect of a low-molecular-mass salt on the thermodynamic stability of stoichiometric interpolymer complexes composed of oppositely charged macromolecules with different solvent affinities has been theoretically studied. It has been shown that the dissociation of such complexes with an increase in the concentration of the salt proceeds via several stages. At a low concentration of the salt, complexes retain their
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ABSTRACT The influence of the cross-linking agent concentration on the macroscopic properties of hypercrosslinked polystyrene networks was studied by means of computer experiment. The computer experiment includes the consecutive stages... more
ABSTRACT The influence of the cross-linking agent concentration on the macroscopic properties of hypercrosslinked polystyrene networks was studied by means of computer experiment. The computer experiment includes the consecutive stages molecular dynamics atomistic simulation of a polystyrene solution, the mapping of atomistic structure onto coarse-grained model, the crosslink formation, the reverse mapping, the determination of properties of samples (elastic modulus and specific surface). The measurements of elastic modulus and specific surface were performed in frameworks of coarse-grained and atomistic presentation. It was shown that for both models the elastic modulus increases while the specific surface decreases with increase of the number of crosslinks. Both models give very close values for specific surface whereas the elastic moduli determined from atomistic simulations could be an order of magnitude greater than the values calculated using the coarse-grained representation of the same sample. The calculated values of the elastic modulus and specific surface are in reasonable quantitative correspondence with experimental data.
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We present a review of theoretical and experimental results on the swelling behavior and collapse transition in polymer gels obtained by our group at Moscow State University. The main attention is paid to polyelectrolyte networks where... more
We present a review of theoretical and experimental results on the swelling behavior and collapse transition in polymer gels obtained by our group at Moscow State University. The main attention is paid to polyelectrolyte networks where the most important factor is additional osmotic pressure created by mobile counter ions. The influence of other factors such as condensation of counter ions,
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Without Abstract
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The effect of a low-molecular-mass salt on the thermodynamic stability of stoichiometric interpolymer complexes composed of oppositely charged macromolecules with different solvent affinities has been theoretically studied. It has been... more
The effect of a low-molecular-mass salt on the thermodynamic stability of stoichiometric interpolymer complexes composed of oppositely charged macromolecules with different solvent affinities has been theoretically studied. It has been shown that the dissociation of such complexes with an increase in the concentration of the salt proceeds via several stages. At a low concentration of the salt, complexes retain their
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The molecular-dynamics method is used to study solutions of amphiphilic macromolecules with a local helical structure. A deterioration in the solvent quality in concentrated solutions of these macromolecules leads to the formation of... more
The molecular-dynamics method is used to study solutions of amphiphilic macromolecules with a local helical structure. A deterioration in the solvent quality in concentrated solutions of these macromolecules leads to the formation of intermolecular fibrillar helix bundles with approximately the same lengths and aggregation numbers. The number of chains in a bundle is determined by parameters that characterize the local
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The destruction of a globule in the presence of a dimeric substrate composed of a hydrophilic group OP and a hydrophobic group H with a high affinity to hydrophobic H units of a macromolecule has been studied. Globules of the homopolymer... more
The destruction of a globule in the presence of a dimeric substrate composed of a hydrophilic group OP and a hydrophobic group H with a high affinity to hydrophobic H units of a macromolecule has been studied. Globules of the homopolymer H macromolecule and the macromolecule of the HP copolymer with proteinlike statistics of monomer unit distribution along a chain
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We observed giant double-stranded DNA chains by fluorescence microscopy in an aqueous environment. We found that the coil-globule transition of T4DNA, 166kbp, induced by spermidine is markedly discrete for individual chains, and... more
We observed giant double-stranded DNA chains by fluorescence microscopy in an aqueous environment. We found that the coil-globule transition of T4DNA, 166kbp, induced by spermidine is markedly discrete for individual chains, and continuous for their ensemble average. Simple theoretical consideration is given taking account of the hierarchy of the system. It is suggested that the unique characteristics of the transition
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By means of computer simulation the association process of diphilic chains with strongly attractive head links (stickers) in the vicinity of critical point of the solvent is studied. The calculations were carried out by means of... more
By means of computer simulation the association process of diphilic chains with strongly attractive head links (stickers) in the vicinity of critical point of the solvent is studied. The calculations were carried out by means of Monte-Carlo simulation with bond-fluctuation model of polymer developed by us for the case of hexagonal-like lattice. It was found that the critical concentration of micelle formation and average aggregation number depend crucially not only on the attraction between stickers but on the quality and state of solvent.
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... 5) Heskins, M.; Guillet, JE J. Macromol. Sci., Chem. 1968, A2, 1441. [CrossRef]. (6) Priest, JH; Murray, SL; Nelson, RJ; Hoffman, AS ACS Symp. Ser. 1987, 350, 275. (7) Schild, HG; Tirrell, DA J. Phys. Chem. 1990, 94, 4352. ...
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... 28, 119991 Moscow, Russia E-mail: lazutin@polly.phys.msu.ru Prof. AN Semenov Institut Charles-Sadron Strasbourg, 23 rue du Loess, 67034 Strasbourg Cedex 2, France E-mail: alexander.semenov@ics-cnrs.unistra.fr Monte ...
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... Valentina V. Vasilevskaya, Pavel G. Khalatur, Alexei R. Khokhlov. Abstract. ... References. A. Baumgärtner, in Application of the Monte Carlo Method in Statistical Physics, edited by K. Binder (Springer, Berlin, 1984), p. 145. PG... more
... Valentina V. Vasilevskaya, Pavel G. Khalatur, Alexei R. Khokhlov. Abstract. ... References. A. Baumgärtner, in Application of the Monte Carlo Method in Statistical Physics, edited by K. Binder (Springer, Berlin, 1984), p. 145. PG Khalatur, SG Pletneva, and GN Marchenko, Russ. ...
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A coarse-grained model is used to study the conformational properties of semiflexible polymers with amphiphilic monomer units containing both hydrophilic and hydrophobic interaction sites. The hydrophobically driven conformational... more
A coarse-grained model is used to study the conformational properties of semiflexible polymers with amphiphilic monomer units containing both hydrophilic and hydrophobic interaction sites. The hydrophobically driven conformational transitions are studied using molecular dynamics simulations for the chains of varying stiffness, as characterized by intrinsic Kuhn segment lengths that vary over a decade. It is shown that the energy of hydrophobic attraction required for the realization of the coil-to-globule transition increases with increasing chain stiffness. For rather stiff backbone, the coil-to-globule transition corresponds to a first order phase transition. We find that depending on the chain stiffness, a variety of thermodynamically stable anisometric chain morphologies are possible in a solvent selectively poor for hydrophobic sites of amphiphilic monomer units. For flexible chains, the amphiphilic polymer forms a cylindrical globule having blob structure with nearly spherical blobs. With increasing stiffness, the number of blobs composing the globule decreases and the shape of blobs transforms into elongated cylinder. Further increase in stiffness leads to compaction of macromolecules into a collagenlike structure when the chain folds itself several times and different strands wind round each other. In this state, the collagenlike structures coexist with toroidal globules, both conformations having approximately equal energies.
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"Swiss-cheese" polyelectrolyte gels (i.e., gels containing a regular set of closed spherical pores) are considered as a... more
"Swiss-cheese" polyelectrolyte gels (i.e., gels containing a regular set of closed spherical pores) are considered as a suitable system for modeling of a medium with extremely inhomogeneous distribution of charged species. It is shown that the inhomogeneous distribution of ions in Swiss-cheese polyelectrolyte gels can be reached simply by immersion of the gels in an aqueous solution of charged species (e.g., low-molecular 1-1 salt or multivalent ions and macroions charged likely to the gel chains). If a polymer gel is kept in such a solution for a long time, the concentration of ions within relatively big voids becomes equal to that in external solution. On the other hand, due to the Donnan effect the ion's concentration in polymer matrix is always lower than that in external solution. As a result the multivalent ions distribute between water voids and polymer matrix. The extent of this distribution is characterized by partition coefficient kD (determined as ratio kD = n(s)(void)/n(s)(mat) of the concentrations n(s)(void) and n(s)(mat) of ions in water voids and in polymer matrix, correspondingly). It is shown that the partition coefficient kD can be larger than 10 for low-molecular salt, reaches 10(3) for bivalent ions, and is higher than 10(6) for tetravalent ions. In the case of polymer macroions the partition coefficient kD tends to infinity. Our calculations show that the lower limit of characteristic scales of heterogeneity (determined by water voids size starting from which the condition of total electroneutrality is fulfilled and effect of partition is the most pronounced) can be equal to tens of nanometers.