Since the mid 1990s soluble, well-characterized high molecular weight metal-containing and metallosupramolecular polymers have become readily available for the first time, even in some cases, with narrow molecular weight distributions and controlled architectures such as block copolymers. This has led to a rapidly expanding interest in their properties and uses. The review provides a survey of the range of applications for these new materials, which combine the processing advantages of polymers with the functionality provided by the presence of metal centers.

Metallopolymers: New Multifunctional Materials

The study of metallopolymers has blossomed into a mature field over the last few decades. Especially, polyferrocenylsilane (PFS) chemistry has taken a tremendous leap and continues to raise intense interest. Since the discovery of thermal ring-opening polymerization (ROP) of sila[1]ferrocenophanes, PFSs have been also accessed by anionic, cationic, transition-metal-catalyzed, and photolytic anionic ROP methodologies. A plethora of synthetic strategies have been devised, enabling access to a wide variety of copolymers, polyelectrolytes, and nanostructured materials. The distinctive physical properties and functions of many PFS-based polymers have been explored, leading to their apt exploitation in technical applications. Therefore, it is conceivable that PFS-related platforms might be indispensable nano-objects in the near future, as they stand on the verge of a new generation of sophisticated materials.

Polyferrocenylsilane-based polymer systems.

This in-depth review covers progress in the area of polyferrocenylsilanes (PFS), a well-established, readily accessible class of main chain organosilicon metallopolymer consisting of alternating ferrocene and organosilane units. Soluble, high molar mass samples of these materials were first prepared in the early 1990s by ring-opening polymerisation (ROP) of silicon-bridged [1]ferrocenophanes (sila[1]ferrocenophanes). Thermal, transition metal-catalysed, and also two different living anionic ROP methodologies have been developed: the latter permit access to controlled polymer architectures, such as monodisperse PFS homopolymers and block copolymers. Depending on the substituents, PFS homopolymers can be amorphous or crystalline, and soluble in organic solvents or aqueous media. PFS materials have attracted widespread attention as high refractive index materials, electroactuated redox-active gels, fibres, films, and nanoporous membranes, as precursors to nanostructured magnetic ceramics, and as etch resists to plasmas and other radiation. PFS block copolymers form phase-separated iron-rich, redox-active and preceramic nanodomains in the solid state with applications in nanolithography, nanotemplating, and nanocatalysis. In selective solvents functional micelles with core–shell structures are formed. Block copolymers with a crystallisable PFS core-forming block were the first to be found to undergo “living crystallisation-driven self-assembly” in solution, a controlled method of assembling block copolymers into 1D or 2D structures that resembles a living covalent polymerisation, but on a longer length scale of 10 nm–10 μm.

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Polyferrocenylsilanes: synthesis, properties, and applications

Metal-containing polymers: Facile tuning of photophysical traits and emerging applications in organic electronics and photonics

Magnetic CoFe alloy@C nanocomposites derived from ZnCo-MOF for electromagnetic wave absorption

We describe the pyrolysis of a highly metallized polymer precursor comprised of a polyferrocenylsilane with pendant cobalt clusters under a reductive atmosphere (N2/H2 = 92%/8%) leading to CoFe magnetic alloy nanoparticle-containing ceramic thin films. Variation of the pyrolysis conditions leads to changes in the nanoparticle size, size distribution, and composition, as well as the ceramic film structure, all of which influence the magnetic properties of the material. When pyrolyzed at 500 °C, the nucleation and growth afford uniform size, larger CoFe nanoparticles on the film surface, and smaller nanoparticles in the underlying layer of the ceramic films. We found that the SiC/C ceramic matrix prevents oxidation of fully embedded nanoparticles, whereas the surface nanoparticles are oxidized on exposure to air. The nanoparticle-containing films are superparamagnetic when pyrolyzed at 600 °C and are ferromagnetic at higher pyrolysis temperatures. The CoFe nanoparticle-containing ceramic thin films have bee...

Pyrolysis of Highly Metallized Polymers: Ceramic Thin Films Containing Magnetic CoFe Alloy Nanoparticles from a Polyferrocenylsilane with Pendant Cobalt Clusters

The synthesis and pyrolysis of a series of soluble, air- and moisture-stable nickel-containing polycarbosilanes (Ni-PCS) is described. The reaction of 1-chloro-1-methyl-silacyclobutane with two different acetylides LiC≡CR (R = phenyl or tert-butyl) yielded the silacyclobutane monomers (CH2)3SiMe(C≡CR) 2a (R = Ph) and 2b (R = t-Bu). Pt(0)-catalyzed ring opening polymerization of 2a and 2b in the presence of Et3SiH gave the alkyne-functionalized polycarbosilanes (PCS) [CH2−CH2−CH2−(Me)Si(C≡CR)]n 3a (R = Ph) and 3b (R = t-Bu) with molecular-weight control. The alkyne groups of the PCS polymers were clusterized with cyclopentadienyl nickel groups to yield samples of Ni-PCSs [CH2−CH2−CH2−(Me)Si(C(NiCp)C(NiCp)R)]n 4a (R = Ph) and 4b (R = tert-Bu) with molecular weights in the range of Mn ≈ 8000−36 000. Pyrolysis of these Ni-PCSs yielded ceramics with embedded Ni or Ni silicide nanoparticles. By adjusting the pyrolysis temperature, it was possible to control the formation of either nickel (400 and 600 °C) or nic...

Pyrolysis of Polycarbosilanes with Pendant Nickel Clusters: Synthesis and Characterization of Magnetic Ceramics Containing Nickel and Nickel Silicide Nanoparticles

Lars Friebe

Papers

Pyrolysis of Highly Metallized Polymers: Ceramic Thin Films Containing Magnetic CoFe Alloy Nanoparticles from a Polyferrocenylsilane with Pendant Cobalt Clusters

Pyrolysis of Polycarbosilanes with Pendant Nickel Clusters: Synthesis and Characterization of Magnetic Ceramics Containing Nickel and Nickel Silicide Nanoparticles