Abstract
AbstractAn electropolymerization of haloalkylhalosilanes (ClRSiCH3Cl2) that possess two types of electroactive sites, that is, the CCl and SiCl bond is described. The one‐pot synthesis method is shown to yield branched polycarbosilanes having a regular carbon block‐spaced silicon backbone structure. A series of branched polycarbosilanes, [RSiCH3]n with R being CH2, C2H4, C3H6, and CH2C6H4C2H4, have been successfully electropolymerized with Mn up to 42,600 Dalton. Experimental and simulation cyclic voltammetry of these monomers and the computational examination of their LUMOs are applied to study the electropolymerization mechanism. The results suggest that polymerization proceeds by iterating steps involving (1) electroreduction of a CCl bond to a carbanion, which is catalyzed by silylanion radical [Cl SiCl(CH3)RCl] and/or Ni(0)/TDA‐1; and (2) nucleophilic attack of carbanions to SiCl bonds of a second monomer or oligomer to extend the polymer chain. The investigation reveals that the R spacer has a considerable impact on the polymerizability of the corresponding monomer. Such interfacial polymerization resembles a template polymerization, leading to unique microstructures that were preserved even after converted to silicon carbide ceramics at high temperatures. © 2008 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 46: 7677–7689, 2008
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