This dissertation is an account of my efforts toward developing strategies for the synthesis of novel functionalized polyhedral oligomeric silsesquioxanes (POSS). These organic/inorganic nanomaterials date back to 1946 and the pioneering work of Scott's synthesis of octamethylsilsesquioxane. POSS cages constitute a framework of silicon-oxygen polyhedron with reactive or inert organic coronae. These hybrid nanostructures are versatile precursors that find applications in polymer chemistry, catalysis, engineering, medicine, and electronics. Their properties are partly dictated by the peripheral organic groups. They are generally benign and easily processible into composite materials with high thermal degradation temperatures, low dielectric constants and superior mechanical properties. These features of POSS compounds have prompted growing interest in their exploration, particularly their use as models for the synthesis of the next generation hybrid nanocomposites. POSS molecules come in different cage sizes with condensed and incompletely condensed structures. The completely condensed analogues are denoted as Tn, where n = number of silicon atoms in the cage and n 9́Æ 6. Whereas the cubic/condensed silsesquioxanes were the initially discovered compounds, most explorations today are focused on the incompletely condensed di-, tri-, and tetra-functional scaffolds because of the ability to derivatize them into more functional materials for a myriad of applications. Even with the partially condensed structures, current research focus on this family of compounds has been dominated by the highly symmetric tetrafunctional octasilsesquioxane otherwise known as the double-decker oligomeric silsesquioxane. This functional POSS precursor has enormous potential for the synthesis of nanosized hybrid clusters with defined shape, structure, and physicochemical properties.In this study, efforts have been made to disclose strategies for the synthesis of asymmetrically functionalized double-decker shaped silsesquioxanes that can serve as nano-linkers to two dissimilar polymer matrices. The conversion of dead-end silsesquioxanes into more functional cage precursors, and surface transformation of cubic and functionalized DDSQs into modifiable precursors for the synthesis of well-defined 3D networks well among my aims. POSS cages used in these investigations were obtained either from commercially available cages or cage-like precursors or were synthesized from monomeric trialkoxy- (or trichloro-)silanes by hydrolytic condensation. Products obtained from this study could open an avenue for the exploration of new structure/property relationships and provide a unique way by which cages can be used as linkers to form both linear POSS/polymer and 3D networks. This research promises to open a new research direction for the synthesis of novel materials that combine three unconventional materials into hybrid POSS/polymer composites. With the asymmetric POSS cage as the building block, unprecedented properties may emerge from the synergy of these building blocks.

Polyhedral oligomeric silsesquioxanes (POSS) have been explored for over 7 decades. These organic/inorganic nanostructures are extremely versatile compounds that are compartible with polymer systems, hence making them ideal components for the synthesis of next generation hybrid materials. Their properties may vary based on the organic peripheral unit, but they are generally environmentally friendly, cheap, easy to process, highly soluble in organic solvents, and exhibit high thermal degradation temperatures, low dielectric constant and high degree of hardness as coating agents. These features of silsesquioxanes have led to a growing interest in the exploration of their chemistry, particularly on their synthesis and applications in polymer synthesis, catalysis, biomedical materials, and electronics. Cubic silsesquioxanes and their double decker (DDSQ) counterparts have been the most useful because these compounds possess the architecture that accommodates functionalization. However, most of the progress recorded to date has been limited to either manipulations on the closed cubic structures or use of double deckers to synthesize functionally symmetric POSS compound. These compounds do display the desired physicochemical properties, but their applications pose the challenge of tethering them with two dissimilar polymeric chains.In this thesis, efforts have been made to develop a route for the selective synthesis of asymmetric POSS compounds that are likely to provide more resourceful applications to the polymer and material sciences. The research utilized the versatility of protecting groups to effect selective functionalization of the DDSQ for entry into the desired target. The asymmetric POSS cage has the potential to allow its dispersal into two dissimilar polymer matrices, generating a POSS/polymer composite that is unprecedented.

The commercial availability and decreasing cost of polyhedral oligomeric silsesquioxanes in recent years has opened up the field to everybody who wishes to apply these unique properties in their own technologies. This is the first book to provide a comprehensive overview of these applications, and covers the synthesis, characterization and history of polyhedral oligomeric silsesquioxanes, their use as metallasilsesquioxane catalysts, their effect upon polymer properties and plastics performance, and their use in superhydrophobic nanocomposites, and electronics, energy, space and biomedical applications. "Applications of Polyhedral Oligomeric Silsesquioxanes" is a valuable reference for those working across a range of disciplines, including chemists, materials scientists, polymer physicists, plastics engineers, surface scientists, and anybody with a commercial or academic interest in plastics, composite materials, space materials, dental materials, tissue engineering, drug delivery, lithography, fuel cells, batteries, lubricants, or liquid crystal, LED, sensor, photovoltaic or biomedical devices.

Combines chemistry and material science in order to provide a complete overview of the design, synthesis, and applications of organo-silica This book offers comprehensive and systematic coverage of the latest developments in functional hybrid silicon copolymers, their applications, and how they were developed in relation to previous works in the preparation of various functional groups terminated silicone materials. Silicon Containing Hybrid Copolymers begins with a chapter that introduces readers to organo-silicon materials. It then presents a chapter on reactive functionally terminated polyorganosiloxanes, and contains a section on the methods and advances of functionalized polyhedral oligomeric silsesquioxanes (POSS) and copolymers. Nanostructured self-assemblies from silicon containing hybrid copolymers are discussed?as are superhydrophobic materials derived from hybrid silicon. Other chapters examine silicone copolymers for healthcare and personal care applications; construction of organic optoelectronic materials by using polyhedral oligomeric silsesquioxanes (POSS); and 3D printing silicone materials and devices. The book also includes an overview of material toughening and fire retardancy in regards to hybrid POSS nanocomposites. This title: -Focuses on design and synthesis strategies, providing a valuable resource for researchers in academia and industry -Presents recent applications, with emphasis on the underlying strategies and the influence from previous designs, in fields such as healthcare and consumer care -Combines synthetic pathways with design specific considerations to provide the reader with greater control over the design process Silicon Containing Hybrid Copolymers is an ideal book for materials scientists, polymer chemists, and bioinorganic chemists.

For fifty years, Hydrosilylation has been one of the most fundamental and elegant methods for the laboratory and industrial synthesis of organosilicon and silicon related compounds. Despite the intensive research and continued interest generated by organosilicon compounds, no comprehensive book incorporating its various aspects has been published this century. The aim of this book is to comprehensively review the advances of hydrosilylation processes since 1990. The survey of the literature published over the last two decades enables the authors to discuss the most recent aspects of hydrosilylation advances (catalytic and synthetic) and to elucidate the reaction mechanism for the given catalyst used and the reaction utilization. New catalytic pathways under optimum conditions necessary for efficient synthesis of organosilicon compounds are presented. This monograph shows the extensive development in the application of hydrosilylation in organic and asymmetric syntheses and in polymer and material science.