Soluble polysilanes

This adventitious finding led to synthesis of the "polysilastyrene" family of Me2Si-PhMeSi copolymers.(11) At almost the same time, soluble polysilanes were reported by Trujillo(12) at Sandia Laboratories and by Wesson and Williams(12) at Union Carbide Co. 

Soluble polysilane polymers can also be used as precursors to silicon carbide. The first such application, using (PhMeSi)n-(Me2Si)m copolymers ("Polysilastyrene"), was to strengthen silicon nitride ceramics. The Si3N4 ceramic body was soaked in polysilane and refired, leading to the formation of silicon carbide whiskers in the pore spaces and a consequent increase in strength. (U)... 

Shortly after Burkhard s publication, a patent by Clark claimed the synthesis of soluble polysilanes, but since this work was never published it was somewhat overlooked. See H. A. Clark,... 

Soluble polysilane derivatives (I) represent a new class of radiation sensitive materials for which a number of new applications have recently appeared. In this regard, they have been utilized as (i) thermal precursors to ceramic materials (2,3) ... 

UV data for the non-ionic water-soluble polysilane 41 (see Section 3.11.4.2.1.(0) were recorded in 20 different solvents.149 Selected spectra are shown in Figure 17. 

Research and development in the field are still continuing at a fast pace, particulady in the area of absorption and emission characteristics of the polymers. Several reasons account for this interest. First, the intractable poly dime thylsilane [30107-43-8] was found to be a precursor to the important ceramic, silicon carbide (86—89). Secondly, a number of soluble polysilanes were prepared, which allowed these polymers to be studied in detail (90—93). As a result of studies with soluble polymers it became clear that polysilanes are unusual in their backbone CT-conjugation, which leads to some very interesting electronic properties. 

The growth of interest in poly(silylene)s is indicated in Figure 5.1, which shows the number of literature publications on polysilanes (and oligosilanes) plotted versus time. Note that few publications appeared before 1980, but during the past 20 years scientific activity in this field has increased dramatically. The interest in polysilanes stems partly from their novel constitution and behavior and partly from their potential utility. The possibility that soluble polysilanes might be precursors to silicon carbide was evident when they were first synthesized, but other technological uses were not so obvious and arose only in the course of research. 

Robert West was bom in New Jersey and educated at Cornell University (B.A.) and Harvard University (A.M., Ph.D.). For the past 45 years he has been a faculty member in the chemistry department at the University of Wisconsin, where he is now E. G. Rochow Professor and Director of the Organosilicon Research Center. His many awards include the Frederick Stanley Kipping Award, the Wacker silicone prize, the Alexander von Humboldt Award, and the main group chemistry medal. He has published more than 600 scientific papers, mostly in the area of silicon chemistry. Major discoveries in his laboratories include the first soluble polysilanes (1978), the silicon-silicon double bond (1981), the first stable silylenes (1994), and electrically conducting organosilanes for high energy density batteries (2000). He is an airplane pilot and a mountaineer, with numerous first ascents in Canada and Alaska. 

FIGURE 25. Molecular structure of synthesized water-soluble polysilane (a) HSC, (b) PSC, and (c) HTSC. (Reprinted from Ref. 106.)... 

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