Polyferrocenylsilanes ceramics

The use of highly crosslinked polyferrocenylsilane networks 3.48 x=y=0) leads to much improved ceramic yields (ca. 90%) and the pyrolytic formation of shaped, magnetic ceramics is efficient. The crosslinked network can be formed by heating the [l]silaferrocenophane, 3.47, in a mold (for 7 h at 150°C and then for 16 h at 180°C). The shape of the resulting crosslinked network 3.48 (x=y=0) resembles the mold used, such as a pentagon (Fig. 3.11). 

Cao L, Massey JA, Winnik MA, Manners I, Riethmuller S, Banhart F, Spatz JP, Mdller M (2003) Reactive ion etching of cylindrical polyferrocenylsilane block copolymer micelles fabrication of ceramic nanolines on semiconducting substrates. Adv Fund Mater 13 271-276... 

Tang and coworkers have reported that pyrolyzed hyperbranched polyferro-cenylsilanes have greater ceramic yields than their linear polymeric counterparts. Manners has reported that thermally crosslinked polyferrocenylsilanes (28) possessed greater thermal stability than their linear analogs. The swelling properties of these crosslinked polymers were examined, and the solubility parameter of the corresponding linear homopolymer was determined. The pyrolysis of linear, hyperbranched, and crosslinked polyferrocenylsilanes has resulted in the production of ceramics that possess magnetic properties. " ... 

Figure 3 SEM micrographs of (a) negatively charged silica microspheres electrostatically bound to the surface of oxidized polyferrocenylsilane microspheres and (b) ahgned strand of spherical magnetic ceramic particles obtained from pyrolysis of polyferrocenylsilane microspheres at 900°C displaying magnetic ordering in an external magnetic field. (Adapted from Ref. 26.)...

Scheme 2 Cobalt clusterization of the acetylenic substituents of a polyferrocenylsilane (2a) to yield the highly metallized Co-PFS (3), a precursor to magnetic ceramics.

It has been demonstrated that polyferrocenylsilanes possess low plasma etch rates, which can be attributed to the formation of a protective layer of involatile iron and silicon compounds. This property has been exploited with PFS block copolymers self-assembled into micelles or phase-separated thin films to deposit patterned ceramics as well as for pattern transfer to the substrate. In our research, we are interested in the direct formation of high metal content magnetic ceramic films by RIE treatment of Co-PFS in the presence of a secondary magnetic field. ... 

Kulbaba K, Cheng A, Bartole A, Greenberg S, Resendes R, Coombs N, Safa-Sefat A, Greedan JE, Stover HDH, Ozin GA, Manners I (2002) Polyferrocenylsilane microspheres synthesis, mechanism of formation, size and charge tunability, electrostatic self-assembly, and pyrolysis to spherical magnetic ceramic particles. J Am Chem Soc 124 12522-12534... 

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