Silicon-containing polymers silarylenes

In order to improve the solubility of aromatic polymers silicon-containing polymers have also been synthesized, by introduction of siloxane or silarylene linkages into polymer backbones such as polyamides, polybenzimidazoles and polyimides [50]. The resultant polymers show fair solubility in organic solvents but most of them have poorer thermal stability then their analogues without siloxane or silarylene linkages. 

We have synthesized some novel silarylene and silarylenesiloxane polymers via dicarbanions prepared from Lochmann s base. Lochmann s base, a powerful metalating reagent composed of equimolar amounts of n-butyl lithium and potassium r-butoxide in a hydrocarbon, has been used to dimetalate compounds such as m-xylene, 4,4 -dimethylbi-phenyl, and 2,3-dimethyl-1,3-butadiene in good yields. In this work the dicarbanion of m-xylene and 4,4 -dimethylbiphenyl have been used to prepare silicon containing monomers and polymers by two different routes. The first route involves a 1 1 condensation reaction between the dicarbanion and a dichlorodiorganosilane to produce a condensation polymer. The second route involves reaction of the dicarbanion with a chlorodiorganosilane which is then converted to a bis(silanol) and then polymerized. Spectroscopic as well as thermal characterization will be presented on the polymers which have been described. 

Silarylene Polymers. Silarylene polymers can be best described as those polymers which contain silicon atoms and phenyl units in the polymer backbone. Perhaps the best example, and the one which has been given the most scrutiny, is poly(tetramethyl-p-silphenylenesiloxane), Q). The major reason which has been cited for incorporating arylene units into this type of polymer has been to increase the thermal stability of the material while maintaining the low temperature flexibility which is associated with siloxane polymers.3.4,5... 

Silarylene Polymers Containing m-Xvlvlene Units. A majority of the silarylene type siloxane polymers which have been worked on to date contain silicon-phenyl bonds. After an extensive literature search, only one type of polymer was found which contained an arylene group that does not have silphenylene bonds in the polymer backbone. The work, done mainly by Rosenberg and Choe 15-17 of the Air Force Materials Laboratory, is based on polymers which have a general structure as shown below, referred to as poly(m-xylylene-siloxanylenes), (9). 

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