Silicon Containing Dendritic Polymers

During the last two decades silicon-containing dendritic polymers have become one of the fastest growing areas of development in polymer science. The eruption of interest in these new polymers stems from their unprecedented molecular architecture, unique resulting properties and the realization that they represent ideal building blocks for chemical nanotechnology. This is the first book to solely focus on silicon-containing dendritic polymers. The contributions of those experts who originally introduced each field or played a major role in its progress are reported. The developments in all major areas of this field are presented from their origins to the present. It is anticipated that this text will become an invaluable guide and vanguard of reference for experienced scientists interested in the fields of polymer and material science, synthetic chemistry, and nanotechnology. It will also serve advanced graduate students either as a source of creative inspiration or as a textbook for appropriate courses.

BACKGROUND Polysiloxanes have chains constructed of alternately arranged silicon and oxygen atoms with organic groups attached to the silicon atoms. This structure gives them a unique combination of properties that hold great interest for a host of practical applications. Although they have been known and manufactured for many years, their applications continue to expand rapidly and this boosts progress in the generation of new and modified polysiloxanes. Polysiloxanes constitute the oldf'"' known class of silicon-based polymers and the broadest one when viewed in terms of the variety of structures differing in topology and the constitution of organic substituents. There are also many and various types of siloxane copolymers, some of purely siloxane structure and others of siloxane-organic composition. There is no doubt that polysiloxanes are the most technologically important silicon-based polymers. The broad class of model materials known as silicones is based on polysiloxanes. They are also the best known, as most research in the area of silicon polymers has for many years been directed towards the synthesis of new polysiloxanes, to understanding their properties and to extending their applications.

Silicon Based Polymers presents highlights in advanced research and technological innovations using macromolecular organosilicon compounds and systems, as presented in the 2007 ISPO congress. Silicon-containing materials and polymers are used all over the world and in a variety of industries, domestic products and high technology applications. Among them, silicones are certainly the most well–known, however there are still new properties discovered and preparative processes developed all the time, therefore adding to their potential. Less known, but in preparation for the future, are other silicon containing-polymers which are now close to maturity and in fact some are already available like polysilsesquioxanes and polysilanes. All these silicon based materials can adopt very different structures like chains, dendrimers, hyperbranched and networks, physical and chemical gels. The result is a vast array of materials with applications in various areas such as optics, electronics, ionic electrolytes, liquid crystals, biomaterials, ceramics and concrete, paints and coatings ... all needed to face the environmental, energetical and technological issues of today. Some industrial aspects of the applications of these materials will also be presented.

Silicon-containing Polymers reflects the growing interest worldwide in this developing field. Silicon polymers are now finding use as moulding materials, rubbers, ceramic precursors, in lithography and reprography as photosensitive materials, as conducting polymers, and in a host of other applications. This book presents up-to-date research from all over the world. It brings together research from the forefront of a multidisciplinary subject, covering the synthesis, modification, characterization, properties and applications of polysiloxanes, polysilylenes, polysilazanes and organosilicate derivatives. Silicon-containing Polymers will be of interest to researchers and postgraduates in any area of materials science, as well as some areas of inorganic chemistry.

Silicon-containing polymers have been a focus of synthesis and study in Dr. Barton's group because of their chemistry and properties which are not offered by other systems or materials. For example, the polymer -[-SiMe2C{triple_bond}C-]{sub n}-can be easily processed to films or fibers from melt or solution, and thermally converted to a SiC-containing ceramic in high yield at high temperature. In recent years, carbosilane dendritic polymers have been of great interests in many research groups. However, no synthesis of carbosilane dendrimers with functionalties both inside and outside the dendrimer has been reported. Functionality is very important in the synthesis of preceramic polymers. This thesis will be devoted to exploring several new organosilicon polymer systems.

The series Advances in Dendritic Macromolecules aims to cover the synthetic, as well as chemical, aspects of this expanding field: the chemistry to and supramolecular chemistry of dendritic or cascade supermolecular compounds. In Chapter 1 of this volume, Hawker and Wooley delineate the convergent growth approach to dendrimers, then relate their three-dimensional architectures to different block polymers. In Chapter 2, Moors and Vögtle describe Professor Vögtle's initial cascade molecules via the repetitive strategy, then expand his original concepts of its application by others, and lastly delineate the synthesis of a new series of tosylamide cascades. They also demonstrate the utility of his original Michael addition/reduction procedure by its application to differ cores. Chapter 3, composed by Professor Engel, describes ionic dendrimers which incorporated an internal transition metal center as well as his work based on ammonium and phosphonium centers. In Chapter 4, Mathias and Carothers review recent studies on silicon-based dendrimers and hyperbranched polymers. Chapter 5, by Kim, describes the preparation and utility of hyperbranched aromatic polymers. Lastly in Chapter 6, Escamilla reviews the historical as well as recent examples of ionic and nonionic bolaamphiphiles.

An overview of the latest advances in the synthesis, characterization and applications of dendrimers and other complex dendritic architectures.

Within this text, for the first time the synthesis, structural characteristics, physical properties, applications and potential applications of polysiloxanes, polycarbosilanes, polysilazanes, polysilanes, and other silicon-containing polymers are detailed. For years to come this book will be the first point of entry for those seeking to learn about the very significant differences that exist between carbon-based polymers and those with silicon in their backbone.

Silicon based materials and polymers are made of silicon containing polymers, mainly macromolecular siloxanes (silicones). This book covers the different kinds of siliconbased polymers: silicones, silsesquioxanes (POSS), and silicon-based copolymers. Other silicon containig polymers: polycarbosilanes, polysilazanes, siloxane-organic copolymers, silicon derived high-tech ceramics: silicon carbide and oxycarbide, silicon nitride, etc. have also a very important practical meaning and a hudge number of practical applications. These materials make up products in a variety of industries and products, including technical and medical applicatons. Polycrystalline silicon is the basic material for large scale photovoltaic (PV) applications as solar cells. Technical applications of crystalline (c-Si) and amorphous (a-Si) silicon (fully inorganic materials), silicon nanowires are still quickly growing, especially in the fi eld of microelectronics, optoelectronics, photonics. and photovoltaics, catalysts, and different electronic devices (e.g. sensors, thermoelectric devices). This book is ideal for researchers and as such covers the industrial perspective of using each class of silicon based materials. Discusses silanes, silane coupling agents (SCA), silica, silicates, silane modified fillers, silsesquioxanes, silicones, and other silicon polymers and copolymers for practical applications as polymeric materials and very useful ingredients in materials science.