Hyperbranched Polycarbosiloxanes: Synthesis by Piers-Rubinsztajn Reaction and Application as Precursors to Magnetoceramics.

Silicon-containing hyperbranched polymers (Si-HBPs) have drawn much attention due to their promising applications. However, the construction of Si-HBPs, especially those containing functional aromatic units in the branched backbones by the simple and efficient Piers-Rubinsztajn (P-R) reaction, has been rarely developed. Herein, a series of novel hyperbranched polycarbosiloxanes were prepared by the P-R reactions of methyl-, or phenyl-triethoxylsilane and three Si-H containing aromatic monomers, including 1,4-bis(dimethylsilyl)benzene, 4,4'-bis(dimethylsilyl)-1,1'-biphenyl and 1,1'-bis(dimethylsilyl)ferrocene, using B(CF) as the catalyst for 0.5 h at room temperature. Their structures were fully characterized by Fourier transform infrared spectroscopy, H NMR, C NMR, and Si NMR. The molecular weights were determined by gel permeation chromatography. The degrees of branching of these polymers were 0.69-0.89, which were calculated based on the quantitative Si NMR spectroscopy. For applications, the ferrocene-linked Si-HBP can be used as precursors to produce functional ceramics with good magnetizability after pyrolysis at elevated temperature.