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Books > Science & Mathematics > Chemistry > Organic chemistry > Polymer chemistry
After epoxy resins and polyimides, cyanate esters arguably form the most well-developed group of high-temperature, thermosetting polymers. They possess a number of desirable performance characteristics which make them of increasing technological importance, where their somewhat higher costs are acceptable. The principal end uses for cyanate esters are as matrix resins for printed wiring board laminates and structural composites. For the electronics markets, the low dielectric loss characteristics, dimen sional stability at molten solder temperatures and excellent adhesion to conductor metals at temperatures up to 250 DegreesC, are desirable. In their use in aerospace composites, unmodified cyanate esters offer twice the frac ture toughness of multifunctional epoxies, while achieving a service tem perature intermediate between epoxy and bis-maleimide capabilities. Applications in radome construction and aircraft with reduced radar signatures utilize the unusually low capacitance properties of cyanate esters and associated low dissipation factors. While a number of commercial cyanate ester monomers and prepoly mers are now available, to date there has been no comprehensive review of the chemistry and recent technological applications of this versatile family of resins. The aims of the present text are to present these in a com pact, readable form. The work is primarily aimed at materials scientists and polymer technologists involved in research and development in the chemical, electronics, aerospace and adhesives industries. It is hoped that advanced undergraduates and postgraduates in polymer chemistry and technology, and materials science/technology will find it a useful introduc tion and source of reference in the course of their studies.
How did life begin on the Earth? The units of life are cells, which can be defined as bounded systems of molecules that capture energy and nutrients from the environment -- systems that expand, reproduce, and evolve over time, often into more complex systems. This book is the proceedings of a unique meeting, sponsored by NATO and held in Maratea, Italy, that brought together for the first time an international group of investigators who share an interest in how molecules self-assemble into supramolecular structures, and how those structures may have contributed to the origin of life. The book is written at a moderately technical level, appropriate for use by researchers and by students in upper-level undergraduate and graduate courses in biochemistry and molecular biology. The overall interest of its subject matter provides an excellent introduction for students who wish to understand how the foundational knowledge of chemistry and physics can be applied to one of the most fundamental questions now facing the scientific community. The editors are pioneers in defining what we mean by the living state, particularly the manner in which simple molecular systems can assume complex associations and functions, including the ability to reproduce. Each chapter of the book presents an up-to-date report of highly significant research. Two of the authors received medals from the National Academy of Science USA in 1994, and other research reported in the book has been featured in internationally recognized journals such Scientific American, Time, and Discover.
The broad field of conformational motion disorder in crystals is described with particular attention to the separation from the well known mesophases of liquid crystals and plastic crystals. Structure, thermodynamics and motion of a larger number of small and large molecules are discussed. Of special interest are the borderlines between smectic and high viscosity liquid crystals and condis crystals and between plastic crystals and condis crystals as complicated by pseudorotation, jumping between symmetry-related states and hindered rotation. This paper illustrates the wide distribution of conformational disorder in nature. Condis crystals and glasses ("Con"formational "Dis"order) can be found in small and large molecule systems made of organic, inorganic and biological compounds. The condis state was newly discovered only four years ago. In this article over 100 examples are discussed as example of the condis state. In many cases the condis state was suggested for the first time. Motion in the Condensed State, Condis Crystals and their Relation to Plastic Crystals, Condis Crystals of Flexible Macromolecules, Condis Crystals and their Relation to Liquid Crystals, Condis Crystals of Stiff Macromolecules.
Viscoelasticandtransportpropertiesofpolymersintheliquid(solution,melt)or liquid-like (rubber) state determine their processing and application to a large extent and are of basic physical interest [1-3]. An understanding of these dynamic properties at a molecular level, therefore, is of great importance. However,thisunderstandingiscomplicatedbythefactsthatdi?erentmotional processes may occur on di?erent length scales and that the dynamics are governed by universal chain properties as well as by the special chemical structure of the monomer units [4,5]. The earliest and simplest approach in this direction starts from Langevin equations with solutions comprising a spectrum of relaxation modes [1-4]. Special features are the incorporation of entropic forces (Rouse model, [6]) which relax uctuations of reduced entropy, and of hydrodynamic interactions (Zimm model, [7]) which couple segmental motions via long-range back ow elds in polymer solutions, and the inclusion of topological constraints or entanglements (reptation or tube model, [8-10]) which are mutually imposed within a dense ensemble of chains. Another approach, neglecting the details of the chemical structure and concentratingontheuniversalelementsofchainrelaxation,isbasedondynamic scalingconsiderations[4,11].Inparticularinpolymersolutions,thisapproach o?ers an elegant tool to specify the general trends of polymer dynamics, although it su?ers from the lack of a molecular interpretation. A real test of these theoretical approaches requires microscopic methods, which simultaneously give direct access to the space and time evolution of the segmental di?usion. Here, quasi-elastic scattering methods play a crucial role sincetheyallowthemeasurementofthecorrespondingcorrelationfunctions.In particular,thehigh-resolutionneutronspinecho(NSE)spectroscopy[12-15]is very suitable for such investigations since this method covers an appropriate range in time (0.005)t/ns)40) and space (r/nm [15). Furthermore, the possibilityoflabellingbyhydrogen-deuteriumexchangeallowstheobservation of single-chain behavior even in the melt.
The renewed and increasing interest in lipid self-assembly, phase behaviour and interfacial properties can be related to both a much improved insight in biological systems and the applications of lipids in food and pharmaceutical industry; in the latter, the development of drug delivery systems based on lipids has become in focus. Amphiphilic systems comprise lipids, surfactants as well as different types of polymers, including block and graft copolymers. Research on biological amphiphiles has often been conducted separate from research on synthetic ones. However, in recent years a very fruitful convergence between the two fields has evolved. These new perspectives on fundamental research and applications of lipids are discussed in these proceedings from an international symposium on "Lipid and Polymer Lipid-systems," October 2000 in Chia Laguna in Italy - a joint undertaking of Prof. Maura Monduzzi at Cagliari University, Italy and Camurus Lipid Research Foundation, Lund, Sweden.
The incessantly interest in aqueous polymer dispersions (APD)
since more than 90 years can be related to the almost unlimited
possibilities to tailor APD to specific needs.
Leading Nordic-Baltic scientists and their colleagues from other countries present recent research on a broad range of topics in surface and colloid science: adhesion, adsorption processes, characterization of solid/liquid and solid/polymer interfaces, chemical and particle depositions, colloid stability, emulsification and encapsulation, interfacial reactions, new surfactants, polymer-surfactant interactions, self-assembly processes, and functionalized surfaces for bio- and chemosensors. The papers were presented at the 1st Nordic-Baltic Meeting on Surface and Colloid Science, which was held in Vilnius, Lithuania on August 21-25, 1999, as a continuation of the traditional Scandinavian Symposium on Surface Chemistry.
The two volumes "New Developments in Polymer Analytics" deal with recent progress in the characterization of polymers, mostly in solution but also at s- faces. Despite the fact that almost all of the described techniques are getting on in years, the contributions are expected to meet the readers interest because either the methods are newly applied to polymers or the instrumentation has achieved a major breakthrough leading to an enhanced utilizaton by polymer scientists. The first volume concentrates on separation techniques. H. Pasch summarizes the recent successes of multi-dimensional chromatography in the characteri- tion of copolymers. Both, chain length distribution and the compositional h- erogeneity of copolymers are accessible. Capillary electrophoresis is widely and successfully utilized for the characterization of biopolymers, particular of DNA. It is only recently that the technique has been applied to the characterization of water soluble synthetic macromolecules. This contributrion of Grosche and Engelhardt focuses on the analysis of polyelectrolytes by capillary electopho- sis. The last contribution of the first volume by Coelfen and Antonietti sum- rizes the achievements and pitfalls of field flow fractionation techniques. The major drawbacks in the instrumentation have been overcome in recent years and the"triple F techniques" are currently advancing to a powerful competitor to size exclusion chromatography.
This volume includes 58 contributions to the 11th International Conference on Surface and Colloid Science, a highly successful conference sponsored by the International Association of Colloid and Interface Scientists and held in Iguassu Falls, Brazil, in September 2003. Topics covered are the following: Biocolloids and Biological Applications, Charged Particles and Interfaces, Colloid Stability, Colloidal Dispersions, Environmental Colloidal Science, Interfaces and Adsorption, Nanostructures and Nanotechnology, Self-Assembly and Structured Fluids, Surfactants and Polymers, Technology and Applications, Colloids and Surfaces in Oil Production. Surface and colloid science has acquired great momentum during the past twenty years and this volume is a good display of new results and new directions in this important area.
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This book is concerned with the configuration of polymers at the interfacial zone between two other phases or immiscible components. In recent years, developments in technology combined with increased attention from specialists in a wide range of fields have resulted in a considerable increase in our understanding of the behavior of polymers at interfaces. Inevitably these advances have generated a wealth of literature and although there have been numerous reviews, a critical treatment with adequate descriptions of both theory and experiment, including detailed analysis of the two, has been missing. This text hopes to fill this gap, providing a timely and comprehensive account of the field as it stands today. This long needed work will be invaluable to experts as well as newcomers in the broad field of polymers, interfaces and colloids, both in industry and academia. Whilst industrial laboratories involved in this field will find it indispensable, it will be equally important to anyone with an interest in interfacial polymer or colloidal research.
In recent years, a growing number of engineering applications of light weight and energy efficient plastics can be found in high quality parts vital to the func tioning of entire equipments and structures. Improved mechanical properties, especially balance of stiffness and toughness, are among the most frequently desired features of the new materials. In addition, reduced flammability is con sidered the single most important requirement for further expansion of plastics into large volume and demanding markets such as construction and mass trans port. Production of power cables also requires flame retardant cable jacketing plastics to replace or at least to reduce consumption of environmentally unsound PVC. The two principal ways to achieve the goals mentioned above include the development of completely new thermoplastic polymers and various modifica tions of the existing ones. Development and commercialization of a new ther moplastic require mobilization of large human and financial resources, the lat ter being within the range from $100 million to $10 billion, in comparison to $100 thousand to $10 million needed to develop and commercialize polymeric mate rial with prescribed end use properties using physical or chemical modification of an existing plastic. In addition, the various markets utilizing thermoplastics demand large flexibility in material properties with only moderate volumes, at the best.
Over the past four decades polymers containing imide groups (usually as build ing blocks of the polymer backbone) have attracted increasing interest of sci entists engaged in fundamental research as well as that of companies looking into their application and commercialization. This situation will apparently continue in the future and justifies that from time to time reviews be published which sum up the current state of knowledge in this field. Imide groups may impart a variety of useful properties to pol~'mers, e. g. , thermal stability chain stiffness, crystallinity, mesogenic properties, photoreactivity etc. These lead to a broad variety of potential applications. This broad and somewhat heteroge neous field is difficult to cover in one single review or monograph. A rather com prehensive monograph was edited four years ago by K. Mittal, mainly concen trating on procedures and properties of technical interest. Most reviews presented in this volume of Advances in Polymer Science focus on fundamen tal research and touch topics not intensively discussed in the monograph by K. Mittal. Therefore, the editor of this work hopes that the reader will appreci ate finding complementary information. Finally I wish to thank all the contributors who made this work possible and I would like to thank Dr. Gert Schwarz for the revision of the manuscripts of the contributions 3 and 4. Hamburg, September 1998 Hans R. Kricheldorf Contents Nanoporous Polyimides J. L. Hedrick, K. R. Carter, l. W. Labadie, R. D. Miller, W.
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