Polysilanes thermal stability

The branched polysilanes show a broad emission peak around 450 nm, where the large red shift in the fluorescence spectra is due to the influence of aryl substituents and the introduction of branched points. For (opto)electronic applications, the UV irradiation and thermal stability are crucial to device stability. Branched polysilanes have better thermostability and are more resistant to UV irradiation than are linear polysilanes. 

The above thermal analysis studies demonstrated the enhanced thermal stability of POSS materials, and suggested that there is potential to improve the flammability properties of polymers when compounded with these macromers. In a typical example of their application as flame retardants, a U.S. patent39 described the use of preceramic materials, namely, polycarbosilanes (PCS), polysilanes (PS), polysilsesquioxane (PSS) resins, and POSS (structures are shown in Figure 8.6) to improve the flammability properties of thermoplastic polymers such as, polypropylene and thermoplastic elastomers such as Kraton (polystyrene-polybutadiene-polystyrene, SBS) and Pebax (polyether block-polyamide copolymer). 

As the diodes suffer considerable heating under work conditions the better performance of the latter polysilane may partly be due to the better thermal stability of aminated polysilanes compared to hydrogen-substituted polymers. Thermogravimetric measurements showed a stability up to 250°C for polyaminophenylsilane while hydrogen-substituted polymers undergo a significant weight loss at temperatures above 100°C. 

Polysilanes are used in these reactions. Preparation of Me2Si from dodecamethylcyclo-hexasilane appears to be the preferred entree into this chemistry for both synthetic and mechanistic studies. In the absence of trapping reagents, the silylene species form oligomers. If irradiation continus more than 20 h, products from radical reactions begin to appear. The thermal decomposition of sterically hindered siliranes also offers a convenient route to silylene intermediates . This is true, for instance, with a base-stabilized... 

---