Polysilsesquioxanes structure

HIGHER ORDER POLYSILSESQUIOXANE STRUCTURE WITH POSS AS CONSTITUTIONAL UNITS... 

Quasi-solid state dye-sensitized solar cells (DSCs) have been constructed using a new polymeric ionic fluid as the electrolyte.119 The electrolyte was synthesized by the sol-gel route using MTMSPI+I as the precursor that was made by derivatizing methylimidazolium with triethyoxysilane. Condensation of this material in the presence of formic acid and in the absence of water led to Si-O-Si-O-type polymerization and formation of a polysilsesquioxane-type structure. When this material was mixed with iodine, it served as a redox electrolyte for DSCs. The DSCs made this way are robust and easy to assemble but their efficiency of 3.1% is relatively low. However, possible improvement lies in modification of the organic groups attached to the polysilsesquioxane backbone. 

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). 

Biotechnology reveals new routes to synthesis and structural control of silica and polysilsesquioxanes... 

Polysilsesquioxanes of general formula R-[SiOj ] n=l are generally prepared by hydrolysis/polycondensation of the corresponding precursors RSiX (X=Q, OR, H). Four basic structures can be envisaged molecular compound with a cage stmcture, polymer with a regular ladder stmcture, polymer with a 3-D disordered structure and lamellar sohd. 

Scheme 5 Cage-Uke structure of Cube polysilsesquioxane (See also Plate 19 in the Colour Plate Section)...

The organo-polysilsesquioxane solids have a polysilsesquioxane-based structure. These systems with precursor containing at least 2 -SiX groups were first developed by Shea et al.[58], and by Corriu et al [59]. and many reviews have covered the topic of their synthesis and reactivity [7,60-62]. 

Polysilsesquioxanes have found a use in the design of 193 nm bilayer resist. The phenol structure has been replaced with cyclohexyl carboxylic acid for... 

Polysilsesquioxanes are a class of compounds having the emperical formula [RSi(0)3/2] , in which three oxygen atoms and one alkyl or aryl group are attached to the silicon atom. These compounds are formed under various reaction conditions and can take various three-dimensional structures. They can be random, ladder, or even cage. Polyhedral oligomeric silsesquioxane (POSS) is usually abbreviated as T , in which n indicates the number of silicon atoms in the frame structure. 

---