Zvelindovsky Nanostructured Soft Matter

Experiment, Theory, Simulation and Perspectives
2007
ISBN: 978-1-4020-6330-5
Verlag: Springer Netherland
Format: PDF
Kopierschutz: 1 - PDF Watermark

E-Book, Englisch, 628 Seiten, eBook

Reihe: NanoScience and Technology

“The scientist does not study nature because it is useful; he studies it because he delights in it, and he delights in it because it is beautiful. If nature were not beautiful, it would not be worth knowing, and if nature were not worth knowing, life would not be worth living. ” Henri Poincar´ e (1854 - 1912) The ancient Greeks, quite ingeniously, realised that all materials and their (now known as macroscopic) properties, including life itself, are due to a limited number of tiny, constantly moving building blocks and the conn- tions (now called interactions) between these blocks. Receiving both scienti?c and non-scienti?c opposition, the idea faded and, despite some renaissance of atomistic ideas in the 17-19th centuries, it still took more than two thousand years, until the time of Einstein, for the idea of microscopic building blocks to be fully accepted. These ideas, begun during the golden age of physics in the 20thcentury,haveledtoacomprehensiveunderstandingofsuchstatesofm- ter as gases and solids, which in turn have completely revolutionised everyday life in the developed world by introducing technological wonders such as m- ern cars, air tra?c, semiconductor chips for computers and nuclear power. Another state of matter, ?uids, appeared to be much more di?cult to tackle, even in the case of simple liquids like liquid argon, a research favourite in the ?eld. Legend tells that Lev D.

Zielgruppe

Research

Autoren/Hrsg.

Zvelindovsky, A.V.

Inhaltsverzeichnis

Experimental Advances.- Microemulsion Templating.- Nanofabrication of Block Copolymer Bulk and Thin Films: Microdomain Structures as Templates.- Characterization of Surfactant Water Systems by X-Ray Scattering and 2H NMR.- Polyelectrolyte Diblock Copolymer Micelles: Small Angle Scattering Estimates of the Charge Ordering in the Coronal Layer.- Structure and Shear-Induced Order in Blends of a Diblock Copolymer with the Corresponding Homopolyme.- Electric Field Alignment of Diblock Copolymer Thin Films.- Control of Block Copolymer Microdomain Orientation from Solution using Electric Fields: Governing Parameters and Mechanisms.- Structure and Dynamics of Cylinder Forming Block Copolymers in Thin Films.- Mathematical and Theoretical Approaches.- Mathematical Description of Nanostructures with Minkowski Functionals.- Scaling Theory of Polyelectrolyte and Polyampholyte Micelles.- The Latest Development of the Weak Segregation Theory of Microphase Separation In Block Copolymers.- Coarse-Grained Modeling of Mesophase Dynamics in Block Copolymers.- Effective Interactions in Soft Materials.- Computer Simulations.- Ab-initio Coarse-Graining of Entangled Polymer Systems.- Computer Simulations of Nano-Scale Phenomena Based on the Dynamic Density Functional Theories: Applications of SUSHI in the OCTA System.- Monte Carlo Simulations of Nano-Confined Block Copolymers.- Understanding Vesicles and Bio-Inspired Systems with Dissipative Particle Dynamics.- Theoretical Study of Nanostructured Biopolymers Using Molecular Dynamics Simulations: A Practical Introduction.- Understanding Liquid/Colloids Composites with Mesoscopic Simulations.

Leseproben

Scaling Theory of Polyelectrolyte and Polyampholyte Micelles (S. 300-301)

Nadezhda P. Shusharina and Michael Rubinstein

Department of Chemistry, University of North Carolina, Chapel Hill, North Carolina 27599-3290, USA

1 Introduction

Polymer solutions have been extensively studied for the past three decades [1–3]. Owing to the successful application of scaling theory [1] the solution properties of uncharged polymers are now reasonably well understood. However, many practically important polymers, both synthetic and natural, are charged in polar solvents, most commonly in water. The added complexity of charged systems stems from their long-range electrostatic interactions. The additional emerging length scales make the scaling approach to charged systems much more challenging than for neutral ones. At the same time, research into the functional materials, drug delivery formulations and stabilization of colloidal systems has led to the development of new types of polyelectrolytes, including charged polymeric surfactants. Study of these new polymers is of great industrial importance and provides an excellent opportunity for the introduction and validation of theoretical approaches. Therefore the theory of solutions of charged polymers remains a quickly developing area of polymer physics and material science [4–6].

In contrast to low-molecular weight compounds, polymers have a very important structural degree of freedom called molecular architecture. Speci.- cally, linear polymer chains can be linked together in di.erent fashions forming a single macromolecule. The control of molecular architecture is a widely used approach in the development of polymers with desired properties [7]. The simplest examples of the chain arrangement are block copolymers, where chemically di.erent chains are linked together end to end, and polymer stars, where several chains are linked at one point. The conformations of polymer subchains in a branched molecule depend on its architecture. For example, the interaction of monomers in a star is stronger than in a linear chain because of the additional interactions between the monomers belonging to di.erent chains (arms). If, for example, the monomers along the chain repel each other, the arms in a star will be more extended than the equivalent linear chains [8]. The structure of polyelectrolyte stars is even more complex [9]. An accumulation of a large charge in a small volume of the star leads to a non-uniform distribution of counterions in solution. The non-uniformity is due to an interplay of the electrostatic energy of the star and the entropy of the counterions.

To lower the electrostatic energy, counterions tend to be con.ned within the volume of the star. However, complete con.nement (condensation) of counterions would lead to a signi.cant loss of their entropy, so the minimum of the free energy is achieved when a fraction of counterions resides within the star, while the remaining counterions are spread throughout the surrounding solution [10,11]. The uncompensated charge of the star leads to a larger extension of the star arms as compared to neutral stars. Moreover, this extension is not uniform because of the existence of two characteristic regions in the star. In the center the concentration of monomers is so high that the short-range monomer-monomer interactions are stronger than the electrostatic long-range interactions. Hence, in the center the extension is the same as in a neutral star. In the outer region the electrostatics dominate, making the extension much larger than that in the corresponding part of a neutral star.