Polysilanes development methods

Organosilicon polymers have attracted much research interest due to their potentially useful properties. For example, the preparation, characterization, and applications of poly(siloxanes) (/), poly(carbosilanes) (2), poly(carbosiloxanes) (S-S), and poly(silanes) (9) have been extensively documented in the literature. Recent research has focused on developing methods for modifying these polymers in order to prepare a variety of substituted derivatives with altered properties. Different approaches used to modify organosilicon polymers have included free-radical hydrosilylation of polysilanes (JO), nucleophilic substitution in poly(chlorosilylenemethylenes) (IJ), hydrosilylation of poly(silylenemethylenes) (12), and deprotonation of... 

Most recently, a simple, mild, one-pot immobilization method was developed to attach the rigid rod-like helical polysilane, poly( -decyl-/-butylsilylene), via a siloxy linkage to hydrophilic quartz or mica substrate surfaces.28 195 Triethylamine was used as a catalyst to couple the Si-H and/or Si-OR termini of the dialkylpolysilane chains (which are generated during the course of Wurtz-type synthesis and workup)51,195 with the surface -OH groups. AFM, UV, and IR data were used to analyze the reactions. 

Methods of successfully synthesizing chtiMcteriz.ible organic polysilanes were developed only in the last decade. With the ud of references given in this chapter, present u synthesis for the homopolymer (MePhSi), and the copolymer (MePhSi) (Me Si), . 

WurtZ-Type Coupling of Dihalosilanes. Several approaches have been developed for the synthesis of polysilanes. However, the most only utilized method is based on the Wurtz-type alkali metal coupling of dichlorosilanes. Both homo- and copolymers can be prepared this way (eq. 

For some uses it is important to form bonds that link different polysilane chains, to transform soluble, meltable polysilanes into insoluble resins. This process is vital if the polysilanes are to be used as precursors to silicon carbide ceramics, since, if cross-linking is not carried out, most of the polymer is volatilized before thermolysis to silicon carbide can take place. Several methods have therefore been developed to bring about cross-linking of polysilanes.109 110... 

The lack of sufficient control of molecular weight distributions, molecular weight and polymer structure of polysilanes via a Wurtz-type coupling reaction led Sakurai and co-workers to develop an alternative method for polysilane synthesis in 1989 [31],... 

One of the separate branches that have reached a qualitatively different stage of their development are sol-gel technologies, which had come a long way from the black box method to the understanding of the chemistry of the process and the order of the major part of the stages that happen under various conditions. Even more successful were the scientists who created the so-called liquid silicon - a polysilane polymer that, under the influence of UV, transforms into polycrystalline silicon, which allows a fundamental change in the production of integrated circuits. 

The first chapter is devoted to the advances in polysilanes. The recent remarkable progress in this field only serves to emphasize the actuality and inexhaustible nature of silicon chemistry. This chapter may present a perfect illustration of how the traditional and would-be thoroughly explored systems can regain our attention due to the development of new technological methods. 

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