Semi-inorganic polymer

The well-known thermal stability of most minerals and glasses, many of which are themselves polymeric, has led to intensive research into synthetic inorganic and semi-inorganic polymers. These materials can be classified into the following groups ... 

A number of polyphosphazenes of repeat unit [-PRR N-] also exhibit liquid-crystalline phases [166-168]. It is certainly intriguing that apparently the only classes of flexible chains that extensively exhibit liquid-crystalline phases are the polysiloxane and polyphosphazene semi-inorganic polymers. 

At the present time, polysiloxanes are unique among inorganic and semi-inorganic polymers. They have been the most studied by far, and are the most important with regard to commercial applications. Thus, it is not surprising that a large number of review articles exist describing the synthesis, properties, and applications of these materials.1 55... 

It is intriguing that even some flexible siloxane polymers form mesomorphic (liquid-crystalline) phases.34 139-166 Some illustrative data are given in Table 4.2. Both poly(diethylsiloxane) and pol y(di-n-propylsiloxane) show two crystalline modifications as well as a mesomorphic phase. (The other major class of semi-inorganic polymers, the polyphosphazenes, are also relatively flexible, and show similarly interesting behavior.)10167... 

This approach has been used to form ceramic-like phases in a wide variety of polymers. The one which has been studied the most in this regard is poly(dimethylsiloxane) (PDMS), the semi-inorganic polymer featured extensively in Chapter 4. This is due to PDMS being in the class of relatively weak elastomers most in need of reinforcement, and being capable of easily absorbing the precursor materials generally used in the sol-gel process. 

CLASS Inorganic and semi-inorganic polymers STRUCTURE [(C5H3Me)Fe(C5H3MeCH2CH2)] ... 

Silicones are semi-inorganic polymers (polyorganosiloxanes) that may be fluid, elastomeric, or resinous, depending on the types or organic groups on the silicone atoms and the extent of cross-linkage between polymer chains. ° An example of silicone resin structure is seen in Figure 5.6. 

The polysiloxanes are by far the most important polymers in the category of inorganic or semi-inorganic polymers, with a large industry devoted to them in numerous countries in the industrialized world. This book attempts to give an overview of these polymers, and to describe some unsolved problems in this area. 

Of the semi-inorganic polymers, the siloxane or "silicone polymers have been studied the most, and are also of the greatest commercial importance (i-i5). The present review provides an overview of some of these polysiloxanes and related materials, emphasizing their structures, most important and interesting physical properties, and a variety of their applications. 

---