bluuebunny/crossref_metadata_2025_split huggingface dataset:
Perfluorinated Polymers, Tetrafluoroethylene–Ethylene Copolymers
Authors: Gangal Subhash V. 
Published: October 2003

AbstractCopolymers of ethylene and tetrafluoroethylene (ETFE) have been studied for more than half a century. However, modified ETFE are the products of real commercial value because they have good tensile strength, moderate stiffness, high flex life, and outstanding impact strength, abrasion resistance, and cut‐through resistance.Electrical properties include low dielectric constant, high dielectric strength, excellent resistivity, and low dissipation factor.Thermal and cryogenic performance and chemical resistance are good. This family of polymers can be processed by conventional methods such as melt extrusion, injection molding, transfer molding, and rotational molding. These polymers are synthesized in aqueous, nonaqueous, or mixed medium with free‐radical initiators. The polymer is isolated and converted into extruded cubes, powders, and beads or a dispersion. The general‐purpose resin is used for insulating and jacketing low voltage power wiring for mass transport system, wiring for chemical plants, and control and instrumentation wiring. It is aslo used to produce sockets, connectors, and switch components. These resins porvide good service in seal glands, pipe plugs, corrugated tubing, fasteners, and pump vanes.
Modeling of Polymer Processing and Properties
Authors: Termonia Yves 
Published: October 2003

Abstract
Kinetic Monte‐Carlo lattice models are presented for the study of the effect of processing conditions on polymer structure and properties. These models clearly reveal the importance of molecular weight, molecular weight distribution, and density of entanglements in controlling the drawability of flexible polymers in the solid state. They have also been used to describe the processes of coagulation and quenching of a polymer solution and they are able to reproduce the wide variety of different polymer structures that can be obtained. Finally, turning to the processing of fibers into planar fibrous materials such as papers and nonwovens, it is shown that kinetic Monte‐Carlo models can be equally successful at predicting their mechanical and permeability properties.
Block Copolymers, Ternary Triblocks
Authors: Abetz Volker 
Published: October 2003

AbstractThis article deals with the self‐assembly of amorphous ABC block copolymers on different levels of hierarchy. After a short general introduction some theoretical background for microphase‐separated block copolymers is given, including the weak and strong segregation limits. Then the influence of the composition and topology on the morphologies of linear and star terpolymers are dealt with, and also the influence of chemical modifications of particular blocks on the morphology is discussed. Finally, the article concludes with investigations on superlattices formed by blends of microphase‐separated block copolymers. This higher level of structural hierarchy can lead to new symmetries such as noncentrosymmetric periodic lamellae or to morphologies showing macrophase separation within a microphase‐separated matrix.
Adhesive Compounds
Authors: Yorkgitis E. M. 
Published: October 2003

AbstractAdhesives comprise one of the chief classes of polymer‐based products. Adhesive bonding is the method of choice for joining many materials, and adhesives see expanded use on a yearly basis because of their versatility and cost‐effectiveness. The market economics of adhesives is summarized and updated. Practical principles of adhesive bonding and formulation are briefly reviewed. Methods of dispensing or applying adhesives are explained in general terms. The many ways in which adhesives can be classified is covered with an emphasis on the physical forms and types of adhesives. The various chemistries used to make pressure‐sensitive, hot‐melt, solvent‐ and water‐based, structural, and natural product adhesives are described in some detail relative to the major constituents commonly used in each as well as the various minor constituents. The general advantages of each class of adhesive are provided. General comments on formulation and the role of the formulator in bringing adhesives to market concludes the article.
Initiators, Free‐Radical
Authors: Myers Terry N. 
Published: October 2003

AbstractMost commercial free‐radical applications employ initiators such as peroxides and azo compounds. Lesser amounts of carbon–carbon initiators and photoinitiators and high energy ionizing radiation are also used commercially to generate free radicals. The chemical initiators are substances possessing labile oxygen–oxygen, carbon–nitrogen, or carbon–carbon covalent bonds that under certain thermal, chemical, or photochemical conditions undergo homolytic scission of the labile bond to produce free radicals. The free radicals produced are useful in many industrial chain reactions, eg, halogenations, additions to carbon–carbon double bonds, polymerizations of vinyl monomers, grafting reactions, curing of rubbers and unsaturated polymers, cross‐linking of polyolefins, modification of polyolefins, and reactive processing.In this article free‐radical initiator decomposition pathways are reviewed. Initiator reactivity is related to chemical structure and to first‐order decomposition parameters such as temperature, frequency factor, and activation energy. Reactivity of derived free radicals is also related to structure and to the occurrence of secondary reactions such as β‐scission and induced decomposition. The energy and the chemical properties of the free radicals determine commercial utility; thus the interrelation of initiators, their kinetics, and the radicals produced provide guidelines for initiator selection.
Langmuir–Blodgett Films
Authors: Lee Christine M. , Talham Daniel R. 
Published: October 2003

Abstract
Langmuir–Blodgett (LB) films provide the opportunity to control the structure of thin films at the molecular level. LB films can be prepared from amphiphilic derivatives of a wide range of functional molecules. Preparation techniques are discussed in this article. The architectural control obtained from the LB technique allows arranging these molecules so that their optical, electrical, and chemical behavior can be controlled. Applications are numerous for such manipulations, and many conceivable uses have already been investigated. There is, yet, much room for improvement and adaptation in the method to prepare even more technologically advanced devices. LB films are the consequence of an age‐old observation, and the technique enjoys a promising future.
Piezoelectric Polymers
Authors: Harrison J. S. , Ounaies Z. 
Published: October 2003

AbstractPiezoelectric polymers have been known to exist for more than 40 years, but in recent years they have gained notoriety as a valuable class of “smart materials.” This article details the current theoretical understanding of the origin of piezoelectric and ferroelectric phenomena in polymers and presents the state‐of‐the‐art in piezoelectric polymers and emerging material systems that exhibit promising properties. Key characterization methods, fundamental modeling approaches, and applications of piezoelectric polymers are discussed.
Polycarbosilanes
Authors: Matsumoto Kozo 
Published: October 2003

AbstractThis article is an overview of polycarbosilane science. Comprehensive reviews of poly(silylenemethylene)s, poly(silyleneethylene)s, poly(silylenetrimethylene)s, poly(silylene‐2‐butenylene)s, poly(silylenevinylene)s, poly(silyleneethynylene)s, and poly(silylenearylene)s are offered, with surveys of some other carbosilane polymers. A synopsis of carbosilane dendrimers is also provided.
Conductive Polymer Composites
Authors: Lu Daoqiang , Luo Shijian , Wong C. P. 
Published: October 2003

AbstractPolymeric materials can be made electronically conductive by adding conductive filler. These materials are called electrically conductive polymer composites. Since their introduction, the electrically conductive polymer composites have been widely used for electromagnetic radiation shielding, heaters, antistatic articles, resistors, and assembling electronic device components, etc. This article reviews two special conductive polymer composites. One is electrically conductive adhesive, which is used to replace tin–lead solder for microelectronic packaging application. The other is conductive polymer composites with large positive temperature coefficients, which can be used for resettable fuses, self‐regulating heaters, etc.
Biotechnology Applications
Authors: Galaev I. Yu. , Mattiasson B. 
Published: October 2003

AbstractStimuli‐responsive polymers undergo reversible phase separation from aqueous solutions triggered by small changes in the environment. The polymers are used in bioseparation (affinity precipitation, aqueous two‐phase polymer systems, smart chromatographic matrices responding to temperature) for production of smart surfaces for the mild detachment of cultivated mammalian cells, as a “chemical valve” regulating porosity of the system, for production of reversibly soluble biocatalysts, as drug‐delivery systems, and for the development of bioanalytical systems.
Molecularly Imprinted Polymers
Authors: Hart Bradley R. , Shea Kenneth J. 
Published: October 2003

AbstractMolecular imprinting is a method with which materials containing highly specific recognition sites with high affinities for a wide range of organic compounds can be made. Since its inception, the number and types of monomers and templates that have been used successfully has increased dramatically. In addition, our understanding of the mechanisms through which the materials operate is increasing. Some areas of application have become well developed and commercial applications are on the horizon. The applications discussed in this article include separation technology, sensors, catalysis, and antibody and receptor site mimics.
Magnetic Polymers
Authors: Rajca Andrzej 
Published: October 2003

AbstractTechnologically important magnetic properties, especially ferromagnetism, are associated with metallic and inorganic materials based on elements with partially filledd‐ andf‐shells. In the past 15 years, the realm of magnetic materials has been expanded to organometallics, organic molecular solids, and most recently, organic polymers. This article reviews recent advances in the area of organic polymers with magnetic properties, including recent discovery of magnetic ordering in a conjugated organic polymer.
Gene‐Delivery Polymers
Authors: Pack Daniel W. 
Published: October 2003

AbstractHuman gene therapy promises to provide unparalleled treatments for afflictions ranging from cystic fibrosis to cardiovascular disease to cancer. The development of safe and efficient methods for delivery of genetic material to specific cells within the body has been a limiting factor in implementation of this technology. Delivery methodologies have included the use of recombinant viruses and synthetic materials, especially cationic polymers. While viruses are by far the most efficient delivery vehicles currently available, polymers exhibit several properties—including very flexible chemistry, potential for biocompatibility, simplicity, and inexpensive synthesis—that make them excellent candidates for the gene delivery vehicles of the future. However, polymers are typically several orders of magnitude less efficient than viruses and are generally considered unacceptable for human gene therapy. Much work is underway to design and synthesize improved polymers for gene delivery applications. This article summarizes the important criteria for an ideal gene delivery vehicle in terms of the potential barriers that must be overcome. Further, the current state of the polymer‐mediated gene delivery field is reviewed and several new classes of polymers, specifically designed for human gene delivery, are described.
Liquid Crystalline Thermosets
Authors: Douglas Elliot P. 
Published: October 2003

AbstractLiquid crystalline thermosets are a new class of materials currently under investigation in a number of research laboratories. Various types of these materials have been described, including liquid crystalline thermosets with epoxy, acrylate and methacrylate, maleimide and nadimide, vinyl, isocyanate and cyanate ester, and ethynyl end groups. These materials have two structural features, a cross‐linked network and liquid crystalline order, which can have a profound influence on each other. The formation of a network during the cross‐linking reaction can have a strong influence on the liquid crystalline structure of the final cured material. In addition, the liquid crystalline structure can have a strong influence on the kinetics of the cure reaction. The liquid crystalline structure also affects the properties of the cured material. For example, fracture toughness is increased and permeability to various liquids is decreased, although the nature of these changes depends on the liquid crystalline phase and the exact morphology of the system. Liquid crystalline thermosets may also be oriented using external fields, such as surfaces, electric fields, and magnetic fields. Orientation has the potential to provide a new processing route for thermosets, leading to unique properties unattainable with conventional thermosets.
Controlled Release Technology
Authors: Kumar Neeraj , Chaubal Mahesh , Domb A. J. , Majeti Ravi Kumar N. V. 
Published: October 2003

Abstract
Controlled release technologies present an invaluable scientific and practical tool for improving performance and safety of drugs. These technologies involve designing the system of materials/drugs/site of action in such a way that barriers surrounding the drug to deliver the latter act with efficacy and safety of the drug at the optimum time and the rate needed. Advances in polymer science have led to the development of several novel drug delivery systems. A proper consideration of surface and bulk properties can aid in designing of polymeric systems for various drug delivery applications. This article is an overview of polymeric controlled release technology starting from fundamentals to applications.
Structural Representation of Polymers
Authors: Schultz John L. , Wilks Edward S. 
Published: October 2003

Abstract
Representations of polymer structures, by both source‐based and structure‐based methodologies, are discussed, compared, and contrasted. The guidelines, called principles by Chemical Abstracts Service and recommendations by the International Union of Pure and Applied Chemistry, on how to represent polymers by both methodologies are explained. Examples are given of how source‐based and structure‐based representations of polymer structures are stored in Chemical Abstracts Service's Registry File, accessible via their Scientific and Technical Information Network, and guidance on how to search for different types of polymers is included. This article covers regular, single‐strand, organic polymers as well as more complex types such as post‐treated; alternating and other periodic; block, comb, and graft; double‐strand (ladder); cross‐linked; dendritic; hyperbranched; hyper‐cross‐linked; inorganic and quasi‐inorganic; oligomers and telomers; siloxanes and silicones; star and star‐block. Stereochemistry in polymers is discussed briefly.
Metallocenes
Authors: Wasserman Eric Paul 
Published: October 2003

AbstractEver since their discovery by Sinn and Kaminsky in 1979, the family of high activity homogeneous olefin polymerization catalysts known as “metallocenes” has been the subject of intense research and commercial development. While a structurally diverse group, metallocene catalysts are generally considered to have a few common features: a highly electrophilic, early transition metal or rare‐earth atom as the point of polymer chain attachment; a π‐bound cyclopentadienyl ring or isoelectronic analogue attached to this atom; and characteristically narrow distributions of polymer molecular weight and short‐chain branching. While polymerization of ethylene and propylene is reviewed in some detail, the nonpolymerization catalysis and (co)polymerization of functional monomers is also surveyed. The current commercial status of metallocene technology is also briefly discussed.
Heterophase Polymerization
Authors: Tauer Klaus 
Published: October 2003

AbstractThis article is an overview of heterophase polymerization techniques in liquid continuous media to prepare polymer dispersions. The common feature of heterophase polymerizations is the distinctive role that interfaces play during all stages and in all aspects of these processes. Accordingly, the heterogeneous nature and its influence on polymerization kinetics and product properties is emphasized rather than a successive treatment of various types of heterophase polymerization techniques such as suspension or emulsion polymerization. Thus, the focus is on colloid chemical and kinetic consequences of the compartmentalization during the polymerization processes.
Living Radical Polymerization
Authors: Klumperman Bert 
Published: October 2003

AbstractLiving Radical Polymerization (LRP) is the general name for a family of polymerization techniques. The techniques have in common that the propagating species is a free radical, and that an equilibrium exists between active (free radical) species and dormant species. Because of this equilibrium (nearly) all chains grow throughout the polymerization reaction. This leads to polymers with predetermined degree of polymerization and (usually) narrow molar mass distribution. A historical overview of the development of LRP is provided, and the three most important techniques are discussed in more detail. These three techniques are (1) nitroxide‐mediated polymerization (NMP), (2) atom transfer radical polymerization (ATRP), (3) reversible addition–fragmentation chain‐transfer–mediated polymerization (RAFT) The general kinetics and some boundary conditions for obtaining low polydispersity index (PDI) polymers are discussed. Further, the scope and limitations of the three major polymerization techniques are outlined.Apart from the predetermined molar mass and the PDI, LRP is of particular interest in the synthesis of advanced architectures. These architectures include block copolymers, star‐branched polymers, telcchelic polymers, gradient or tapered copolymers, etc. Among the major advantages of LRP is the fact that most of the benefits of free‐radical polymerization (FRP) are retained. Thus, the possibility to (co)polymerize functional monomers (hydroxyl, epoxy, amide, anhydride, etc) and the possibility to polymerize under nondemanding conditions are typical for FRP as well as for LRP.
Ziegler–Natta Catalysts
Authors: Chadwick John C. 
Published: October 2003

AbstractThis article describes the development and characteristics of Ziegler–Natta catalysts for the polymerization of ethylene, propylene, and other alpha‐olefins. Particular emphasis is given to state‐of‐the‐art MgCl2/TiCl4/donor catalysts for polypropylene, including current insight into mechanistic aspects of Ziegler–Natta catalysis in relation to catalyst performance and polymer molecular composition and properties.Ziegler–Natta catalysts are multisite systems, in which the nature and the distribution of the active species can be steered to give polymers having different tacticity and molecular weight distributions. MgCl2‐supported catalysts have almost totally replaced the TiCl3catalysts used previously and have enabled the development of cost‐efficient bulk and gas‐phase polymerization processes. Spherical particle morphology and controlled particle size and porosity have been achieved and this has played an important role in the widespread application of these catalysts.
Ethylene Copolymers
Authors: Guest Martin J. , Cheung Y. Wilson 
Published: October 2003

AbstractCopolymerization of ethylene (E) and styrene (S) has been enabled by developments in metallocene catalysts. An overview of copolymerization chemistry shows that catalyst structure and polymerization conditions have major influences on the production efficiency, product composition, and copolymer microstructure. Copolymers produced have included those with alternating (ES)nsequences; when these sequences are stereoregular, they can crystallize. Ethylene and styrene have been copolymerized with additional monomers, including dienes and α‐olefins.Ethylene–styrene copolymers have been primarily produced via solution polymerization techniques. To date, the copolymers of major interest are essentially atactic, and contain up to about 50 mol% styrene. These copolymers range from highly crystalline to essentially amorphous, dependent upon comonomer composition ratio. The structure–property relationships presented include thermal properties, viscoelastic behavior, mechanical properties, and rheology/processability. Materials engineering is important regarding the utility of poly(ethylene‐co‐styrene). The copolymers are compatible with bitumens, plasticizers, and tackifiers. Blend systems with copolymers as components and copolymer/filler composites are discussed. Potential markets/applications for poly(ethylene‐co‐styrene) have been identified from literature sources, and include foams.
Template Polymerization
Authors: Połowiński Stefan 
Published: October 2003

AbstractTemplate polymerizationis defined asa process of polymer synthesis in which the monomer units are organized by a preformed macromolecule (template) and refers to one phase systems in which the monomer and template are soluble in the same solvent. The general characteristics of template polymerization, polycondensation, and copolymerization are discussed. Associated kinetic, molecular, and tacticity effects are also considered. Typical examples of template polymerization systems and products of template polymerization such as interpolymer complexes and ladder‐type polymers are presented. Possible applications are briefly described.
Phase Transformation
Authors: Binder Kurt , Müller Marcus 
Published: October 2003

AbstractThis article briefly summarizes some key theoretical concepts about phase transformations, discusses the extent to which they differ from related phenomena in other materials, and mentions a few typical experiments to introduce the main techniques used to study such phase transitions. Phase transformations of polymeric materials, such as unmixing of a polymer solution or polymer blend, or the crystallization of a polymer melt or its glass transition into an amorphous structure, are very common phenomena and have important applications.Polymers in the solid state rarely reach full thermal equilibrium. Of course, all amorphous materials can be considered as frozen fluids, whereas polymers typically are semicrystalline, where amorphous regions alternate with crystalline lamellae, and the detailed structure and properties are history‐dependent. Such out‐of‐equilibrium aspects are out of the scope of the present article, which rather emphasizes general facts of the statistical thermodynamics of phase transitions and their applications to polymers in fluid phases.