Self-Assembly of Model Nonionic Amphiphilic Molecules

Guerin, Claudia B. E.; Szleifer, Igal

doi:10.1021/la980788n

Cited by 52 publications

(45 citation statements)

References 35 publications

(85 reference statements)

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“…Although the equilibrium is primarily controlled by the free energy differences among the surfactant molecules located in bulk water, end-capped portion and middle portion of the micelles, it also depends on intermicellar interactions. [17][18][19][20][21] Analyses of scattering data for micellar solutions at finite concentrations are considerably involved, since concentration-dependent intermicellar interactions and micellar growth concomitantly occur in the solutions and the contributions from both effects are not easily decoupled.…”

mentioning

confidence: 99%

Wormlike Micelles of Polyoxyethylene Alkyl Ethers CiEj

Einaga¹

2009

Polym. J.

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It is demonstrated that wormlike micelles of nonionic surfactants polyoxyethylene alkyl ethers H(CH 2 ) i (OCH 2 CH 2 ) j OH (C i E j ) have been successfully characterized by static (SLS) and dynamic light scattering (DLS) measurements and viscometry with the aid of the theories developed so far in the field of polymer solution studies, i.e., a molecular thermodynamic theory for light scattering, chain statistical and hydrodynamic theories for semi-flexible polymers. The results for the excess Rayleigh ratio, radius of gyration, hydrodynamic radius, and intrinsic viscosity have been shown to be well represented by the theories based on a wormlike spherocylinder model. Some salient features found for the micelles of C i E j with various i or j, their binary mixtures, and the micelles including n-alcohol and n-alkane are discussed. The nonionic surfactant polyoxyethylene mono-alkyl ether H(CH 2 ) i (OCH 2 CH 2 ) j OH, (abbreviated C i E j ), exhibits a wide variety of phases in aqueous solution as a function of surfactant concentration and temperature. 1,2 Here, i and j denote the number of methylene groups in the alkyl group and that of repeating units in the oxyethylene group, respectively. At dilute regime, the C i E j + water binary system forms an isotropic phase, that is so-called L 1 phase, which consists of micelles formed with the amphiphilic molecules and water. The system exhibits the LCST behavior; the micellar solutions are phaseseparated into two phases at high temperatures. It is now well established that the micelles grow in size with increasing concentration and raising temperature, in particular to a greater extent when approaching the phase boundary, assuming threadlike or wormlike cylindrical shape. (See Figure 1.) The wormlike micelles have been visually shown by the cryo-TEM observation, 3 in which in the process of micellar growth, threadlike or polymer-like micelles are evolved in the solutions examined. The micelles are, thus, sometimes called ''living'' or ''equilibrium'' polymers in a sense that the linear macromolecules formed can break and recombine.The polymerlike micelles have certain similarities to real polymers and then their solution properties are analogous to those of real polymer solutions. They have been, thus, rather widely studied to characterize their shape and size by employing the theoretical concepts and experimental methods developped in the polymer solution studies, such as static (SLS) and dynamic light scattering (DLS), [3][4][5][6][7][8][9][10][11][12] small-angle neutron scattering (SANS), 13-15 viscometry, 15,16 pulsed-field gradient NMR, 4-7 and so forth. However, solutions of polymer-like micelles are essentially different from those of real polymers. The molar mass of the micelle, i.e., the aggregation number, varies with surfactant concentration, temperature, and other solvent conditions. The average value and distribution of the micellar size are determined by multiple chemical equilibrium among micelles with various aggregation numbers. Although the equi...

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mentioning

confidence: 99%

Wormlike Micelles of Polyoxyethylene Alkyl Ethers CiEj

Einaga¹

2009

Polym. J.

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“…Metallic nanocrystals (4) have various well studied shapes. Closed shapes in self-assembled soft-matter simple systems, including shells such as viral capsids (5), vesicles (6,7), and emulsions (8), as well as micelles (9,10), are understood in uncharged components systems. However, because symmetry has its roots in molecular interactions, charged molecules may form a large variety of self-assembled closed shapes, with potentially complex symmetries.…”

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confidence: 99%

Faceting ionic shells into icosahedra via electrostatics

Vernizzi¹,

Cruz

2007

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

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Shells of various viruses and other closed packed structures with spherical topology exhibit icosahedral symmetry because the surface of a sphere cannot be tiled without defects, and icosahedral symmetry yields the most symmetric configuration with the minimum number of defects. Icosahedral symmetry is different from icosahedral-shaped structures, which include some large viruses, cationic-anionic vesicles, and fullerenes. We present a faceting mechanism of ionic shells into icosahedral shapes that breaks icosahedral symmetry resulting from different arrangements of the charged components among the facets. These self-organized ionic structures may favor the formation of flat domains on curved surfaces. We show that icosahedral shapes without rotational symmetry can have lower energy than spheres with icosahedral symmetry caused by preferred bending directions in the planar ionic lattice. The ability to create icosahedral shapes without icosahedral symmetry may lead to the design of new functional materials. The electrostatically driven faceting mechanism we present here suggests that we can design faceted polyhedra with diverse symmetries by coassembling oppositely charged molecules of different stoichiometric ratios.membranes ͉ self-assembly ͉ amphiphiles ͉ buckling

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“…77 Additional studies done by other groups with this type of model include the study by Guerin and Szleifer on the cmc and the micellar size distribution as a function of the A and B block lengths and temperature. 79 The hydrophobic region was found to be more compact for longer hydrophobic blocks and for lower temperatures. Another study on polymer brushes dissolved in a good solvent 80 showed very good agreement with experimental results for PS but not for PEO.…”

Section: Self-consistent Field Theorymentioning

confidence: 96%

Computer simulation of aqueous block copolymer assemblies: Length scales and methods

Ortiz

Nielsen

Klein

et al. 2006

J Polym Sci B Polym Phys

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Atomistic, coarsegrain, and mesoscopic computer simulation methods applied recently to the study of block copolymer assemblies in solution are reviewed. At the atomic level, particle-based simulations have provided insight into specific interactions such as hydrogen bonding between polymer and water.Coarse-grain models have given a generalized view of the conformations of polymer chains in solvents of different qualities by grouping clusters of atoms into effective interaction sites. Mesoscopic selfconsistent field theory allows for the study of the phase diagram of block copolymers in water using a mean-field continuum description. [1907][1908][1909][1910][1911][1912][1913][1914][1915][1916][1917][1918] 2006 Keywords: all-atom; coarse-grain; DPD; field theory; molecular dynamics Kingston, ON in 1996. In 1998, he received his M.Sc. and Ph.D. degrees from the University of Toronto for his work on the statistical mechanics of mixed quantum-classical systems under the supervision of Raymond E. Kapral. He then moved on to join the group of Michael L. Klein at the University of Pennsylvania as a postdoctoral research associate to work on coarse-grain models of membranes. His current research interests are on the solubilization of carbon nanotubes by cyclic peptides and on a detailed molecular understanding of colloidal stability.

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Self-Assembly of Model Nonionic Amphiphilic Molecules

Cited by 52 publications

References 35 publications

Wormlike Micelles of Polyoxyethylene Alkyl Ethers CiEj

Wormlike Micelles of Polyoxyethylene Alkyl Ethers CiEj

Faceting ionic shells into icosahedra via electrostatics

Computer simulation of aqueous block copolymer assemblies: Length scales and methods

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