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The rapidly-developing field of confined polymers is reviewed in this volume. Special emphasis is given to polymer aspects of this interdisciplinary problem. Taken together, the contributions offer ample evidence of how the field of polymer science continues to evolve with the passage of time. The topics revolve around the tendency of surfaces to impede chain relaxation and to stimulate new sorts of chain organization. These have been implicated in a variety of spectacular phenomena. Here is a listing of authors and affiliations: K. Binder (Johannes Gutenberg-Universität Mainz, Germany); P.-G. de Gennes (College de France, France); E.P. Giannelis, R. Krishnamoorti, and E. Manias (Cornell University and University of Houston, USA); G.S. Grest (Exxon Research and Engineering Co., USA); L. Leger, E. Raphael, and H. Hervet (College de France, France); S.-Q. Wang (Case Western Reserve University, USA).
The rapidly-developing field of confined polymers is reviewed in this volume. Special emphasis is given to polymer aspects of this interdisciplinary problem. Taken together, the contributions offer ample evidence of how the field of polymer science continues to evolve with the passage of time. The topics revolve around the tendency of surfaces to impede chain relaxation and to stimulate new sorts of chain organization. These have been implicated in a variety of spectacular phenomena. Here is a listing of authors and affiliations: K. Binder (Johannes Gutenberg-Universität Mainz, Germany); P.-G. de Gennes (College de France, France); E.P. Giannelis, R. Krishnamoorti, and E. Manias (Cornell University and University of Houston, USA); G.S. Grest (Exxon Research and Engineering Co., USA); L. Leger, E. Raphael, and H. Hervet (College de France, France); S.-Q. Wang (Case Western Reserve University, USA).
Polymers are essential to biology because they can have enough stable degrees of freedom to store the molecular code of heredity and to express the sequences needed to manufacture new molecules. Through these they perform or control virtually every function in life. Although some biopolymers are created and spend their entire career in the relatively large free space inside cells or organelles, many biopolymers must migrate through a narrow passageway to get to their targeted destination. This suggests the questions: How does confining a polymer affect its behavior and function? What does that tell us about the interactions between the monomers that comprise the polymer and the molecules that confine it? Can we design and build devices that mimic the functions of these nanoscale systems? The NATO Advanced Research Workshop brought together for four days in Bikal, Hungary over forty experts in experimental and theoretical biophysics, molecular biology, biophysical chemistry, and biochemistry interested in these questions. Their papers collected in this book provide insight on biological processes involving confinement and form a basis for new biotechnological applications using polymers. In his paper Edmund DiMarzio asks: What is so special about polymers? Why are polymers so prevalent in living things? The chemist says the reason is that a protein made of N amino acids can have any of 20 different kinds at each position along the chain, resulting in 20 N different polymers, and that the complexity of life lies in this variety.
This research project investigated the physical aging of glassy polymers in confined environments. Many recent studies of aging in glassy polymers have observed that aging behavior is often strongly affected by confinement. Understanding aging in confined environments (e.g., thin polymer films and nanocomposites) is vital for predicting long-term performance in applications that use confined glassy polymers, such as gas separation membranes and advanced nanocomposite materials. Aging in bulk and layered films produced via layer-multiplying co-extrusion was studied using gas permeability measurement and differential scanning calorimetry (DSC). The layered films consisted of polysulfone (PSF) and a rubbery co-layering material, with PSF layers ranging in thickness from ~185 nm to ~400 nm. Gas permeation aging studies at 35 °C revealed that the PSF layers in layered films aged in a manner that was similar to bulk PSF and independent of layer thickness. This finding differs from what was observed previously in freestanding PSF films, in which aging depended strongly on thickness and was accelerated relative to bulk. Isothermal aging studies at 170 °C and cooling rate studies were performed on both bulk and layered samples using DSC. The aging of the PSF layers was similar to aging in bulk PSF for films having PSF layer thicknesses of ~640 nm and ~260 nm, while the film with 185 nm PSF layers showed a slightly higher aging rate than that of bulk PSF. The results of the DSC studies generally support the conclusions of our gas permeation aging studies. The absence of strong thickness dependence in aging studies of layered films tends to support the idea that the effect of film thickness on physical aging stems from interfacial characteristics and not merely thickness per se. The physical aging of thin polystyrene (PS) films at 35 °C was also investigated using gas permeation techniques. PS films of 400 nm and 800 nm did not exhibit aging behavior that was highly accelerated relative to bulk or strongly dependent on film thickness. At the thicknesses and aging temperature considered, the aging of PS shows much weaker thickness dependence than that seen in polymers like PSF and Matrimid.
Polymers are one of the most versatile and important materials used for capsule preparation despite various others available. Suitably formulated capsules can securely protect ingredients, deliver them to targeted sites, and release them expeditiously, improving functions and minimizing adverse effects. New polymers are constantly being explored to develop more efficient capsules as they are routinely used in pharmaceuticals, consumer healthcare products, nutrients, and food. This book focuses on the current state of the art of polymer-based capsules and delivery systems. It describes the formulation processes of capsules developed from redox-responsive polymers and polymer-functionalized carbon nanotubes, in addition to shedding light on coacervation of polymers for encapsulation. It reviews different active ingredients that can be used with polymer capsules in various products, encapsulation of essential oils using such capsules, and development of polymer capsules of cells and bacteriophages.
Polymers are essential to biology because they can have enough stable degrees of freedom to store the molecular code of heredity and to express the sequences needed to manufacture new molecules. Through these they perform or control virtually every function in life. Although some biopolymers are created and spend their entire career in the relatively large free space inside cells or organelles, many biopolymers must migrate through a narrow passageway to get to their targeted destination. This suggests the questions: How does confining a polymer affect its behavior and function? What does that tell us about the interactions between the monomers that comprise the polymer and the molecules that confine it? Can we design and build devices that mimic the functions of these nanoscale systems? The NATO Advanced Research Workshop brought together for four days in Bikal, Hungary over forty experts in experimental and theoretical biophysics, molecular biology, biophysical chemistry, and biochemistry interested in these questions. Their papers collected in this book provide insight on biological processes involving confinement and form a basis for new biotechnological applications using polymers. In his paper Edmund DiMarzio asks: What is so special about polymers? Why are polymers so prevalent in living things? The chemist says the reason is that a protein made of N amino acids can have any of 20 different kinds at each position along the chain, resulting in 20 N different polymers, and that the complexity of life lies in this variety.
Integrating latest research results and characterization techniques, this book helps readers understand and apply fundamental principles in nonlinear polymer rheology. The author connects the basic theoretical framework with practical polymer processing, which aids practicing scientists and engineers to go beyond the existing knowledge and explore new applications. Although it is not written as a textbook, the content can be used in an upper undergraduate and first year graduate course on polymer rheology. • Describes the emerging phenomena and associated conceptual understanding in the field of nonlinear polymer rheology • Incorporates details on latest experimental discoveries and provides new methodology for research in polymer rheology • Integrates latest research results and new characterization techniques like particle tracking velocimetric method • Focuses on the issues concerning the conceptual and phenomenological foundations for polymer rheology • Has a companion website for readers to access with videos complementing the content within several chapters
This book examines the current state of the art, new challenges, opportunities, and applications in the area of polymer nanocomposites. Special attention has been paid to the processing-morphology-structure-property relationship of the system. Various unresolved issues and new challenges in the field of polymer nanocompostes are discussed. The infl
The design of polymer blends constitutes an interesting alternative to obtaining micro- and nanostructured surfaces. The cost is reasonable and it is free from time-consuming procedures. Blending of polymers can yield materials with unprecedented properties that cannot be provided otherwise by using a single polymer. The free surface topography of polymer blend films, often related to phase domain structure, is critical to the applications. Two main aspects need to be considered in the preparation of multistructured blends: the interfaces involved and the morphology to be obtained. The control of these two aspects depends further on materials-related parameters involving the composition of the blend, the interfacial tension or viscosity ratio, and the processing conditions related to the temperature, time, or intensity of mixing, among others. Both domain structure and topography of the blend films have garnered increasing interest over the past decade. This chapter describes the nanomicrostructures formed at the polymer surface from polymer blends. Despite the crucial role that surfaces play in the final application of the material, up to now most of the studies concerning polymer blends have been related to the control of the mechanical properties (toughness, stiffness, thermal expansion, etc.), their barrier properties, or the electrical conductivity. This chapter focuses on the analysis of the structured polymer surfaces and thin films, giving an overview of the role of these structures on the final application. The principles of phase separation and the resulting structures formed are briefly discussed, followed by a wide overview of the possibilities of producing stimuli-responsive interfaces by introducing, among other things, pH- or temperature-responsive polymers within the blend. Finally, we look at how using particular preparation conditions and/or self-assembly of block copolymers, the formation of films and surfaces with hierarchical order length-scales can be induced. We also examine the main areas in which multiscale-ordered interfaces obtained from polymer blends have been applied.