Boron-containing polymers advances

This volume of the series focuses on the photochemistry and photophysics of metal-containing polymers. Metals imbedded within macromolecular protein matrices form the basis for the photosynthesis of plants. Metal-polymer complexes form the basis for many revolutionary advances occurring now. The contributors to many of these advances are authors of chapters in this volume. Application areas covered in this volume include nonlinear optical materials, solar cells, light-emitting diodes, photovoltaic cells, field-effect transistors, chemosensing devices, and biosensing devices. At the heart of each of these applications are metal atoms that allow the assembly to function as required. The use of boron-containing polymers in various electronic applications was described in Volume 8 of this series. 

Boron- and Nitrogen-Containing Polymers for Advanced Materials 103... 

The area of organoboron polymers containing borazine and its derivatives is covered in Chapter 5 of this book by Miele and co-workers. Miele and Bernard also describe the utilization of these polymers in ceramics, fibers, and so on, in Chapter 3 of this book. In this section, the utilization of polymers containing borazine or in some cases the bicyclic boron ligand, 9-BBN, for the production of SiC or Si/C/B fibers is briefly described. Recent advances in polypyrazolylborate or pyrazabole-containing polymers and other boron ring system-derived polymers also have been briefly described. 

Boron-containing nonoxide amorphous or crystalline advanced ceramics, including boron nitride (BN), boron carbide (B4C), boron carbonitride (B/C/N), and boron silicon carbonitride Si/B/C/N, can be prepared via the preceramic polymers route called the polymer-derived ceramics (PDCs) route, using convenient thermal and chemical processes. Because the preparation of BN has been the most in demand and widespread boron-based material during the past two decades, this chapter provides an overview of the conversion of boron- and nitrogen-containing polymers into advanced BN materials. 

The most studied class of boron polymers containing boron-silicon bonds are the carboranylenesiloxane polymers. The history of these polymers was discussed at the beginning of this chapter. The more recent advances in this group of polymers and in silicon-containing borazine and boroxine polymers are discussed in later sections of this chapter. In this section, some remaining groups of silicon-containing boron polymers are discussed. 

Specifically, the greatest emphasis in the following chapters is placed on polyphosphazenes (1.9), polysiloxanes (1.10), and polysilanes (1.11). Chapters 6 and 7 introduce a wide variety of other polymers that contain elements such as phosphorus, germanium, sulfur, boron, aluminum, and tin, and a variety of transition metals. These polymers are expected to provide the basis for many of the new advances of the future. Chapter 8... 

Ceramic-type materials that contain no organic linkage units can be prepared by the pyrolysis of cyclic or high polymeric aminophosphazenes. An example is shown in reaction (44). Under appropriate conditions, pyrolysis products that correspond to phosphorus-nitride are formed. Polyphosphazenes that contain both amino and borazine side groups yield phosphorus-nitrogen-boron ceramics following pyrolysis 94,95 The conversion of a formable polymer into a ceramic has many potential advantages for the controlled synthesis and fabrication of advanced ceramics. This principle is discussed in more detail in Chapter 9. 

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