Reptation of living polymers: dynamics of entangled polymers in the presence of reversible chain-scission reactions

Cates, M. E.

doi:10.1021/ma00175a038

Cited by 964 publications

(1,019 citation statements)

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“…The possibility of branched supramolecular organizations has attracted considerable interest (19)(20)(21). Evidence of branching has been reported mainly for aqueous surfactant solutions, but reversed structure such as lecithin organogels also can form three-way junctions (22).…”

Section: Tem Examination Of Samples Prepared Through the Quick-freeze͞mentioning

confidence: 99%

Molecular self-assembly of surfactant-like peptides to form nanotubes and nanovesicles

Vauthey

Santoso

Gong

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

801

701

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Several surfactant-like peptides undergo self-assembly to form nanotubes and nanovesicles having an average diameter of 30 -50 nm with a helical twist. The peptide monomer contains 7-8 residues and has a hydrophilic head composed of aspartic acid and a tail of hydrophobic amino acids such as alanine, valine, or leucine. The length of each peptide is Ϸ2 nm, similar to that of biological phospholipids. Dynamic light-scattering studies showed structures with very discrete sizes. The distribution becomes broader over time, indicating a very dynamic process of assembly and disassembly. Visualization with transmission electron microscopy of quickfreeze͞deep-etch sample preparation revealed a network of openended nanotubes and some vesicles, with the latter being able to ''fuse'' and ''bud'' out of the former. The structures showed some tail sequence preference. Many three-way junctions that may act as links between the nanotubes have been observed also. Studies of peptide surfactant molecules have significant implications in the design of nonlipid biological surfactants and the understanding of the complexity and dynamics of the self-assembly processes.amino acids ͉ charged and hydrophobic residues ͉ nonlipid surfactants ͉ simplicity to complexity ͉ prebiotic enclosures M olecular self-assembly recently has attracted considerable attention for its use in the design and fabrication of nanostructures leading to the development of advanced materials (1, 2). The self-assembly of biomolecular building blocks plays an increasingly important role in the discovery of new materials and scaffolds (3, 4), with a wide range of applications in nanotechnology and medical technologies such as regenerative medicine and drug delivery systems (5, 6). Recently, Hartgerink et al. (7) reported the design of a chimeric material consisting of a hydrophobic alkyl tail and a hydrophilic peptide containing phosphorylated serine with an RGD motif that facilitates directional alignment of mineralization of hydroxyapatite.We previously described a class of ionic self-complementary peptide that spontaneously self-assemble to form interwoven nanofibers in the presence of monovalent cations (8 -10). These nanofibers further form a hydrogel consisting of greater than 99.5% water. The constituent of the hydrogel scaffold is made of peptides with alternating hydrophilic and hydrophobic amino acids. Such a sequence has a tendency to form an unusually stable ␤-sheet structure in water (8 -10). When the peptides form a ␤-sheet, they exhibit two surfaces, a hydrophilic surface consisting of charged ionic side chains and a hydrophobic surface with hydrophobic side chains. As a result, the self-assembly of these peptides is facilitated by electrostatic interactions on one side and the hydrophobic interaction on the other, in addition to the conventional ␤-sheet hydrogen bond along the backbones. The self-assembling peptide scaffolds have been demonstrated to serve as substrate for tissuecell attachment, extensive neurite outgrowth, and formation of active n...

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Section: Tem Examination Of Samples Prepared Through the Quick-freeze͞mentioning

confidence: 99%

Molecular self-assembly of surfactant-like peptides to form nanotubes and nanovesicles

Vauthey

Santoso

Gong

et al. 2002

Proc. Natl. Acad. Sci. U.S.A.

801

701

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“…7 However, unlike covalent chemical bonding polymers, self-assembled wormlike micelles are in dynamic equilibrium with their monomers, which are called "living polymers" owing to their ability to break and recombine rapidly. 8,9 The viscoelastic wormlike micelles often show relaxation behavior that can be described by a Maxwell model with a single relaxation time, a living polymer model proposed by Cates et al 9À11 Viscoelastic wormlike micelles formed by ionic surfactants, especially cationic surfactants, upon addition of various additives have been studied extensively. 12À18 The additives are either simple inorganic salts or structure-forming benzyl hydrotropes, with the molar ratio of salt to surfactant typically above 1 for the former while much lower for the latter.…”

mentioning

confidence: 99%

A Dually Effective Inorganic Salt at Inducing Obvious Viscoelastic Behavior of both Cationic and Anionic Surfactant Solutions

Xia

Wang

et al. 2011

Langmuir

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Viscoelasticity, induced by the entanglement of wormlike or threadlike micelles, has been observed in various surfactant systems and drawn considerable interest in both fundamental and applied science owing to the systems' special rheological properties. 1À6 The rheology of these viscoelastic surfactant fluids is similar to that of the solutions of flexible polymers. 7 However, unlike covalent chemical bonding polymers, self-assembled wormlike micelles are in dynamic equilibrium with their monomers, which are called "living polymers" owing to their ability to break and recombine rapidly. 8,9 The viscoelastic wormlike micelles often show relaxation behavior that can be described by a Maxwell model with a single relaxation time, a living polymer model proposed by Cates et al. 9À11 Viscoelastic wormlike micelles formed by ionic surfactants, especially cationic surfactants, upon addition of various additives have been studied extensively. 12À18 The additives are either simple inorganic salts or structure-forming benzyl hydrotropes, with the molar ratio of salt to surfactant typically above 1 for the former while much lower for the latter. The most interesting features of wormlike micellar solutions are their fascinating microstructural evolution and their linear and nonlinear viscoelastic behavior, depending on the interaction between the surfactant and additive molecules. Inorganic counterions (e.g., F À , Cl À , Br À , NO 3 À ) bind moderately to cationic micelles and thus lead to gradual micellar growth by screening the repulsion between the charged headgroups, 19À22 but for the same charged surfactants, i.e., anionic surfactants, the inorganic salts only play a role in regulating the ionic strength of the solutions. 23 Moreover, at high concentrations of surfactant and salt, phase separation often occurs due to the formation of precipitate, which is generally called the salting-out effect. 24À26 Compared with inorganic salts, organic counterions or hydrotropic salts that strongly bind to the micellar surface are highly efficient in promoting micellar growth 16,22,27 and inducing wormlike micelles at a significantly low ratio of salt to surfactant. However, similar to inorganic salts, only the oppositely charged hydrotropic salts can induce such microstructure transition and viscoelastic behavior in surfactant systems. On the whole, these additives induce complicated viscoelastic responses which are strongly dependent on the electric properties of the additives, and only the oppositely charged additives can show strong interaction with the surfactants, regardless of whether they are inorganic salts or hydrotropic salts.Although simple additive effects for ionic surfactants have been studied extensively, there are few reports of the abovementioned effects induced only by one salt for both cationic and anionic surfactants. It is believed that the present study is the first example that inorganic salt induces micellar growth and viscoelastic behavior significantly in both cationic and anionic surfactant soluti...

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“…If a good time scale separation exists, eq. (1.62) implies that c ≡ P (0 + ) = 1 − exp (−H I ) is the fraction of correlated transitions, κ (2) = 1 − c being the estimate according to the present analysis of the average probability for a newly created free arm to recombine by the Poisson "mean field" kinetic process postulated by Cates in his theory [9]. We now explain how the estimate of the cumulative hazard function is constructed.…”

Section: Cumulative Hazard Analysismentioning

confidence: 91%

“…Let c(t, L) be the number of chains per unit volume having a size L at time t. Cates [9] writes the kinetic equations as…”

Section: A Kinetic Model For Scissions and Recombinationsmentioning

confidence: 99%

“…Unlike the latter, which have been much studied during the last 50 years [6,7,8], theoretical work on micellar solutions are quite recent [1,2]. While building up a molecular scale theory is clearly too heavy for such complex systems, theoretical approaches, based on mean-field concept and non-local phenomenological approaches, can explore with success some equilibrium, and rheological properties [9,10,11], under reasonable but often drastic approximations. Concerning specifically micelle kinetics, recently, O'Shaughnessy and Yu [12] suggested that there are two possible kinds of kinetics associated with scission/recombination: diffusion controlled and mean-field, which may be distinguished by the time dependence of the first recombination times distribution function of the chains.…”

Section: Introductionmentioning

confidence: 99%

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Reaction Kinetics of Coarse-Grained Equilibrium Polymers: A Brownian Dynamics Study

Huang

Crevel

et al.

Computer Simulations in Condensed Matter Systems: From Materials to Chemical Biology Volume 2

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Self-assembled linear structures like giant cylindrical micelles or discotic molecules in solution stacked in flexible columns are systems reminiscent of polydisperse polymer solutions, ranging from dilute to concentrated solutions as the overall monomer density and/or the chain length increases. These supramolecular polymers have an equilibrium length distribution, the result of a competition between the random breakage of chains and the fusion of chains to generate longer ones. This scissionrecombination mechanism is believed to be responsible of some peculiar dynamical properties like the Maxwell fluid rheological character for entangled micelles. Simulations employing simple mesoscopic models provide a powerful approach to test mean-field theories or scaling approaches which have been proposed to rationalize the structural and kinetic properties of these soft matter systems. In the present work, we review the basic theoretical concepts of these "equilibrium polymers" and some of the important results obtained by simulation approaches. We propose a new version of a mesoscopic model in continuous space based on the bead and FENE spring polymer model which is treated by Brownian Dynamics and Monte-Carlo binding/unbinding reversible changes for adjacent monomers in space, characterized by an attempt frequency parameter ω. For a dilute and a moderately semi-dilute state-points which both correspond to dynamically unentangled regimes, the dynamic properties are found to depend upon ω through the effective life time τ b of the average size chain which, in turn, yields the kinetic reaction coefficients of the mean-field kinetic model proposed by Cates. Simple kinetic theories seem to work for times t ≥ τ b while at shorter time, strong dynamical correlation effects are observed. Other dynamical properties like the overall monomer diffusion and the mobility of reactive end-monomers are also investigated.

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Reptation of living polymers: dynamics of entangled polymers in the presence of reversible chain-scission reactions

Cited by 964 publications

References 4 publications

Molecular self-assembly of surfactant-like peptides to form nanotubes and nanovesicles

Molecular self-assembly of surfactant-like peptides to form nanotubes and nanovesicles

A Dually Effective Inorganic Salt at Inducing Obvious Viscoelastic Behavior of both Cationic and Anionic Surfactant Solutions

Reaction Kinetics of Coarse-Grained Equilibrium Polymers: A Brownian Dynamics Study

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