Polysilane polymers applications

In this chapter, an introduction and overview of polysilane chemistry will be presented, concentrating on the linear high polymers (polysilanes) and their technological applications. Polysilane polymers were reviewed in 1986,(1) and a more general review of polysilane chemistry appeared in 1982.(2)... 

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)... 

In a very interesting development, increasing the potential of polysilanes for application yet further, polysilanes have been end-grafted onto substrate surfaces using a variety of approaches. This surface-tethering of polysilanes requires the functionalization of one end (terminus) of the polymer main chain with a group which can be attached to a reactive surface or derivatized surface. 

The condensation of secondary silanes requires more rigorous conditions and no catalyst has yet been reported to couple tertiary silanes efficiently [140]. The great interest in polysilane polymers and their potential application come from their unusual electronic, optical, and chemical properties [142], particularly as preceramic materials [143]. The reaction constitutes the only alternative to Wurtz coupling for the formation of silicon-silicon bonds. 

There are, however, other classes of inorganic and organometallic polymers that deserve consideration due to their considerable scientific and applicative relevance, such as polysilanes [28-31], polycarbosilanes [32,33],polysilazanes [33],polyborazines [34,35],polythiazenes [36], and, as an example,polymetal-locenylsilanes [37]. 

A rapidly increasing number of publications on polysilanes documents current interest in these polymers (JJ. Polysilanes are potentially applicable in microlithography as high resolution UV-resists (2J, imageable etch barriers ), or contrast enhancement layers (4). They have been successfully used as precursors to Si-C fibers (5J and ceramic reinforcing agents ((L). Polysilanes have also initiated polymerization of vinyl monomers (J ). Doping of polysilanes have increased their conductivity to the level of semiconductors (8). Very recently polysilanes were used as photoconductors (9) and non-linear optical materials (10b... 

The first CEM system described by Griffing and West (84) consisted of an organic dye dispersed in an inert polymer film that is spin coated onto the surface of a resist and subsequently removed following exposure but prior to resist development. The chemistry of this system is based on the photoisomerization of an aromatic dye to an oxaziridine (87) (Figure 10). Other workers have evaluated polysilanes (88) and diazonium salt chemistry (89,90) for CEM applications. 

Other polymers containing Si in the main chain are the polysilanes. The discovery that polysilane derivatives were radiation sensitive(20), coupled with their stability in an oxygen plasma, has led to a number of microlithographic applications(14, 21-24). For the... 

Went, M. J. Sakurai, H. Sanji, T. Modification and Functionalization of Polysilanes. In Silicon-based Polymers The Science and Technology of their Synthesis and Application-, Jones, R. G., Ando, W., Chojnowski, J., Eds. Kluwer Dordrecht, 2000 pp 419-437. 

Polysilanes absorb electromagnetic energy and undergo chain scission. This is an extremely important property of these polymers in terms of applications, Photochemistry is exhibited both in solution and in the solid slate. 

---