Molecular polysilastyrene

Molecular mechanics techniques are employed to calculate the molecular structure and conformational energies of model compounds for polyphenylmethylsllylene and polysilastyrene. In both isotactic and syndiotactic stereochemical forms. The structural and conformational energy data provided are used to calculate, by application of the RIS theory, the unperturbed chain dimensions, given as the characteristic ratio, and its temperature coefficient. 

Partially pvrolvzed poivsilastyrene membranes. Molecular sieve membranes can also be made from porous solids other than carbon and zeolitic materials. One such potential candidate is the family of precursors of silicon carbide. Among the possible precursors, polysilastyrene (phenylmeihylsilane-dimethylsilane copolymer) is commercially available and soluble in many common solvents such as toluene and tetrahydrofuran and can be crosslinked by UV radiation. Polysilastyrene is comprised of long chains of silicon atoms ... 

E. Grosgogeat, J.R. Fried, R.G. Jenkins and S.T. Hwang, A method for the determination of the pore size distribution of molecular sieve materials and its application to the characterization of partially pyrolyzed polysilastyrene/porous glass composite membranes. /. Membr. Sci., 57 (1991) 237. 

Polysilastyrene is also prepared in a way similar to polysilane as shown in eq. (8.52). Actually the polysilastyrene having x = 0.5-0.6, due to consideration of its yield and the price of its raw materials, is prepared. The molecular weight is around 30000-60000. The SiC is produced by releasing organic gas with calcination of polysilastyrene at 1200-1600°C under an argon atmosphere [61]. 

Polysilastyrene absorbed < 350nm UV radiation and its molecular weight easily decreases by breaking of the Si—Si bonds. Therefore, the polysilastyrene can be used as a photoresist. Other various kinds of poly silanes have been developed, as shown in Table 8.8 [61]. 

Further testing [535] was confirmed the procedure for producing polysilastyrene , and has established that the polymers are stable in the open air to about 300 C. They are insoluble in acetone, methanol, acetonitrile and hexane. Their solubility in toluene, tetrachloromethane and chloroform has been measured as a function of the molecular weight of the polymer. 

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