Preface

Research in functional materials science is one of the strategic top-priority areas of development in science and technology. Environmentally friendly and cost-efficient multifunctional materials are indispensable for our modern society. Owing to their broad range of properties, polymers are used as thermoplastics, thermosets, and elastomers, and after being processed into fibers and films or used in the design of structural materials, they play an essential and ubiquitous role in everyday life. In this area, inorganic polymeric materials are growing in importance as a result of increased demand for new materials with specific properties. Inorganic polymers have remarkable properties that can be superior to those of their organic counterparts in a variety of ways including, for example, thermal stability (polysilazanes) and controlled degradability in drug-delivery systems. This facilitates their use as water repellents, flame retardants, and metal-ion conductors in batteries (polyphosphazenes), as well as precursors for ceramics, microlithography, and electroluminescent devices (polysilanes). Furthermore, the discovery of new synthetic avenues to metallopolymers has led to the rapid growth of this field and to the wide range of applications for these functional materials. Inorganic polymers offer an innovative approach to sustainability by switching from hydrocarbon/oil-based polymers to heteroelement-based polymers and lessen the burden on scarce nonrenewable resources or even provide full replacements. In terms of applications, inorganic polymers are now found in many consumer products, demonstrating their technological importance; investigation of new applications continues in laboratories worldwide.

At the European level, many academic and industrial research groups have a long-standing interest in inorganic polymers or smart materials. The idea to join their forces in the framework of a COST Action raised European competitiveness in this area to new levels. Effectively, with the COST Action CM1302: European Network on Smart Inorganic Polymers (s), it was possible to give this exciting research area a new forum and a new voice. Funding priorities and opportunities are very different throughout Europe. Bringing scientists from such diverse backgrounds together has a far-reaching impact that will reverberate for many years to come. New collaborations involving inclusiveness target countries (ITCs) have emerged, for example between Portugal and Spain, Croatia and Germany, as well as Romania and France. A generation of young researchers from all over Europe has been trained in European training schools and in Short-Term Scientific Missions to receive state-of-the-art skills and expertise. Working together has been inspirational, many fundamental questions have been addressed, and for many more the ground has been prepared. Different dissemination tools have been used to increase the interest, awareness, and the visibility of this COST Action (web pages, press releases, international conferences, etc.). The final dissemination of the COST Action is the present book entitled Smart Inorganic Polymers: Synthesis, Properties and Emerging Applications in Materials and Life Sciences.

This book showcases some of the research highlights that emerged during the COST Action and at the same time hopes to entice the reader into the world of smart inorganic polymers and its vibrant, pan-European community. The book is aimed at academics and industrial researchers in this field, and also at scientists who want to get a better overview on the state of the art of this rapidly advancing area.

Chapter 1 by Rudolf Pietschnig provides an overview of the use of smart inorganic materials in daily life. For example, some polymers have the ability to undergo facile electronic excitation giving rise to materials with tunable color (electro/thermochromism) or switchable surface polarity (hydrophobicity/hydrophilicity). Such properties enable adaptive windows for privacy, security, and heat management. Rudolf Pietschnig has also been the dissemination manager of the COST Action SIPs. His group is recognized for the development of silanol-based surfactants.

The following chapters present the synthesis, properties, and applications of polymers incorporating different heteroelements such as boron, phosphorus, silicon, germanium, and tin.

Anne Staubitz, the equal opportunity manager of SIPs and an expert in the development of Group 13/15 element analogs of organic materials, describes together with her coworkers Jonas Hoffmann and Philipp Gliese the synthesis and properties of polymers incorporating Group 13 and Group 15 elements in Chapter 2.1. The properties of these polymers are remarkably different from those of the corresponding organic polymers: their higher polarity (boron-nitrogen vs. carbon-carbon []) or greater flexibility (boron-phosphorus vs. carbon-carbon []) leads to different solubilities or glass transition temperatures. They may be used as preceramic polymers, which is unthinkable for organic polymers. Many more exciting properties are yet to be discovered. In Chapter 2.2, Clara Viñas, leader of the working group in SIPs dealing with advanced applications of inorganic polymers, and her colleagues Rosario Núñez, Isabel Romero, and Francesc Teixidor emphasize the role of hollow spherical icosahedral boron clusters in the properties of polymeric and nanohybrid structures. The incorporation of such clusters into these structures not only improves their solubility, stability, and processability, but also boosts their electronic, optical, and thermal properties. All these properties make them promising materials for technological and biomedical applications.

With the rising interest in applying Group 14-based materials in the field of electronics and energy-related materials, Chapter 3 by Ana Torvisco, David Scheschkewitz, and Frank Uhlig presents the preparation of stable Group 14 metal-containing linear polymers, focusing on metal hydrides (R n EH4-n , E = Ge, Sn) as building blocks. In addition, the application of trihydrides REH3 toward the preparation of novel branched polymeric networks is described. David Scheschkewitz and Frank Uhlig have been leaders of the working group in SIPs dealing with the development of inorganic molecular building blocks.

Chapter 4 by Andreas Orthaber and Alejandro Presa Soto summarizes the synthesis of polymers of phosphorus and the heavier pnictogens comprising unsaturated motifs, such as phosphazene or phosphaalkene, as well as saturated motifs, e.g. phosphane and phosphole or P(=O)O units. They detail the synthesis of suitable precursors and specific polymerization methods that lead to functional and smart materials.

In Chapter 5, Anne-Marie Caminade (specialist in inorganic dendrimers and leader of the working group in SIPs dealing with the synthesis of smart inorganic polymers) describes the synthesis of "inorganic" dendrimers comprising either silicon or phosphorus branching points with emphasis on carbosilane and phosphorhydrazone dendrimers. A few miscellaneous examples of dendrimers based on germanium, tin, or bismuth branching points are also presented. The properties of these dendrimers, presented in Chapter 10, are relevant to three main fields: (i) catalysis, with emphasis on the "dendritic effect" and the possibility of recovering and reusing the dendritic catalysts; (ii) nanomaterials exclusively composed of dendrimers, or materials incorporating inorganic dendrimers in their structure, or surfaces of materials modified with inorganic dendrimers; and (iii) biology/nanomedicine with applications in bioimaging, gene therapy, and for treatment of viruses, brain diseases, cancers, and inflammatory diseases.

In Chapter 6, Jirí Vohlídal, an expert in metallosupramolecular polymers, and Muriel Hissler focus on constitutionally dynamic polymers (dynamers) whose chains consist of alternating molecular units with two or more chelating end-groups (unimers) and metal ions linked by coordination. This chapter provides in brief the classification of dynamers and related terms, synthetic approaches to unimers, methods of monitoring the self-assembly and characterization of metallosupramolecular dynamers, as well as their functional properties and potential applications.

Chapter 7 highlights the different kinds of heteroatom-based materials that have been used in electronic devices, such as organic light-emitting diodes (s), organic photovoltaic () cells, dye-sensitized solar cells (s), organic field-effect transistors (s), and electrochromic cells. This chapter has been written by Muriel Hissler, co-chair and STSM coordinator of COST Action SIPs, and her coworkers Matthew P. Duffy and Pierre-Antoine Bouit.

Owing to their intrinsic structures, most smart inorganic polymers show excellent thermal stability and fire retardancy. De-Yi Wang and Tarik Eren, having extensive expertise in fire-retardant materials, detail the synthesis and fire-retardant properties of different classes of polymers in Chapter 8 together with their coworker Raghvendra Kumar Mishra.

Inorganic...