Polyferrocenylsilane Microspheres: Synthesis, Mechanism of Formation, Size and Charge Tunability, Electrostatic Self-Assembly, and Pyrolysis to Spherical Magnetic Ceramic Particles

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• 作者：Kevin Kulbaba ; Alison Cheng ; Alexandra Bartole ; Sharonna Greenberg ; Rui Resendes ; Neil Coombs ; Athena Safa-Sefat ; John E. Greedan ; Harald D. H. Stö ; ver ; Geoffrey A. Ozin ; and Ian Manners
• 刊名：Journal of the American Chemical Society
• 出版年：2002
• 出版时间：October 23, 2002
• 年：2002
• 卷：124
• 期：42
• 页码：12522 - 12534
• 全文大小：926K
• 年卷期：v.124,no.42(October 23, 2002)
• ISSN：1520-5126

文摘

Pt(0)-catalyzed ring-opening precipitation copolymerization of [1]silaferrocenophanes fcSiMe₂(3) and the spirocyclic cross-linker fcSi(CH₂)₃ (4) (fc = Fe(es/gifchars/eta.gif" BORDER=0 >⁵-C₅H₄)₂) was used to prepare polyferrocenylsilanemicrospheres (PFSMSs) under mild conditions. By varying the reaction conditions, a wide variety of othermorphologies was obtained. The effects of temperature, monomer ratio, solvent composition, catalystconcentration, and time on the observed morphology were investigated and interpreted in terms of amechanism for microsphere formation. The most well-defined particles were formed using equimolar amountsof 3 and 4, in a 50:50 mixture of xylenes and decane at 60 es/entities/deg.gif">C with gentle agitation. Chemical oxidation ofthe polymeric microspheres led to positively charged particles (OPFSMSs) which underwent electrostaticallydriven self-assembly with negatively charged silica microspheres to form core-corona composite particles.Redox titration with controlled amounts of the one-electron oxidant [N(C₆H₄Br-p)₃][PF₆] in acetonitrile ledto the oxidation of the outer 0.15 es/entities/mgr.gif">m (ca. 32%) of the PFSMSs. The resulting OPFSMSs were reducedback to their neutral form by reaction with hydrazine in methanol. Pyrolysis of the PFSMSs led to sphericalmagnetic ceramic replicas with tunable magnetic properties that organize into ordered 2-D arrays at theair-water interface under the influence of a magnetic field.