Convenient approach to Si–H-containing polymers


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Abstract

New synthetic routes to organosilicon polymers containing SiH2 groups and organic π-electron units in the polymer main chain are described. These polymers are expected to be useful precursors for ceramics. The polymer backbone is formed by condensation of α,ω-bis(trifluoromethylsulfonyloxy)-substituted organo-silicon compounds containing SiH2 groups with the organometallic dinucleophiles Li2C2, Li2C4, and 1,4-BrMg–C6H4–MgBr. We could confirm the formation of the silicone polymers at low temperatures, in short reaction times, and with high yields. The structural characterization is based on 29Si, 13C, and 1H NMR spectroscopy. The narrow 29Si NMR signals of the products indicate the regular alternating arrangement of the building blocks in the polymer backbone resulting from the fact that the condensation reactions are not accompanied by exchange processes analogous to metal halogen exchange. Weight-average molecular weights in the range of Mw = 10000–20000, relative to polystyrene standards, were found by GPC. The pyrolytic behaviour of [H2Si−H2Si−C ≡ C−]n2a is compared with the behaviour of the methylated derivative [Me2Si−Me2Si−C ≡ C−]n.

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