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Synthesis of core-crosslinked carbosilane block copolymer micelles and their thermal transformation to silicon-based ceramics nanoparticles



Carbosilane fine particles were synthesized by core-crosslinking of carbosilane block copolymer micelles and they were pyrolytically transformed into silica nanoparticles. The carbosilane block copolymer, poly(1-(3-butenyl)-1-methylsilacyclobutane)-block-polystyrene, (polyBMSB-b-polySt), [(m, n) = (31, 16), (54, 30), and (75, 28)], was synthesized by anionic polymerization of BMSB and St, where m and n represent polymerization degrees of BMSB and St segments, respectively. The block copolymer formed micelles in N,N-dimethylformamide (DMF). The hydrodynamic diameters (Dh) of the micelles evaluated by dynamic light scattering ranged from 40 to 158 nm depending on the copolymer molecular weight. The core of the micelle was cross-linked by Pt-catalyzed hydrosilation with 1,2-bis(dimethylsilylethane). The Dh of the core-cross-linked micelles in THF ranged from 56 to 164 nm. These precursor particles were pyrolyzed at 850 °C under N2 to give ceramic nanoparticles. The diameters of the spherical ceramic particles estimated by AFM ranged from 25 to 60 nm. X-ray fluorescence analysis of the ceramic products revealed that it consisted of mainly SiO2 rather than SiC. © 2005 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 43: 3778–3787, 2005