Hyperbranched Poly(ferrocenylene)s Containing Groups 14 and 15 Elements: Syntheses, Optical and Thermal Properties, and Pyrolytic Transformations into Nanostructured Magnetoceramics

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(C₆F₅)₃ as the catalyst for 0.5 h at room temperature. Their structures were fully characterized by Fourier transform infrared spectroscopy, ¹H NMR, ¹³C NMR, and ²⁹Si 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 ²⁹Si 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.

Metallopolymers for advanced sustainable applications

Since the development of metallopolymers, there has been tremendous interest in the applications of this type of materials. The interest in these materials stems from their potential use in industry as catalysts, biomedical agents in healthcare, energy storage and production as well as climate change mitigation. The past two decades have clearly shown exponential growth in the development of many new classes of metallopolymers that address these issues. Today, metallopolymers are considered to be at the forefront for discovering new and sustainable heterogeneous catalysts, therapeutics for drug-resistant diseases, energy storage and photovoltaics, molecular barometers and thermometers, as well as carbon dioxide sequesters. The focus of this review is to highlight the advances in design of metallopolymers with specific sustainable applications.

Hollow Superparamagnetic Microballoons from Lifelike, Self-Directed Pickering Emulsions Based on Patchy Nanoparticles

Herein, the formation of hollow microballoons derived from superparamagnetic iron oxide nanoparticles with silica patches is reported. Depending on the experimental conditions, single- or multishelled superparamagnetic microballoons as well as multivesicular structures were obtained. We show how such structural changes follow a lifelike process that is based on self-directing Pickering emulsions. We further demonstrate that the key toward the formation of such complex architectures is the patchy nature of the nanoparticles. Interestingly, no well-defined ordering of patches on the particles surface is required, unlike what theorists formerly predicted. The resultant hollow microballoons may be turned into hollow carbonaceous magnetic microspheres by simple pyrolysis. This opens the way to additional potential applications for such ultralightweight (density: 0.16 g·cm^-3) materials.

Polyferrocenylsilanes: synthesis, properties, and applications

This comprehensive review covers polyferrocenylsilanes (PFSs), a well-established, readily accessible class of main chain organosilicon metallopolymer. The focus is on the recent advances involving PFS homopolymers and block copolymers and the article covers the synthesis, properties, and applications of these fascinating materials.

Ceramic Nanocomposites from Tailor-Made Preceramic Polymers

The present Review addresses current developments related to polymer-derived ceramic nanocomposites (PDC-NCs). Different classes of preceramic polymers are briefly introduced and their conversion into ceramic materials with adjustable phase compositions and microstructures is presented. Emphasis is set on discussing the intimate relationship between the chemistry and structural architecture of the precursor and the structural features and properties of the resulting ceramic nanocomposites. Various structural and functional properties of silicon-containing ceramic nanocomposites as well as different preparative strategies to achieve nano-scaled PDC-NC-based ordered structures are highlighted, based on selected ceramic nanocomposite systems. Furthermore, prospective applications of the PDC-NCs such as high-temperature stable materials for thermal protection systems, membranes for hot gas separation purposes, materials for heterogeneous catalysis, nano-confinement materials for hydrogen storage applications as well as anode materials for secondary ion batteries are introduced and discussed in detail.

Single-source magnetic nanorattles by using convenient emulsion polymerization protocols

A novel strategy to achieve easily scalable magneto-responsive nanoceramics with core/shell and nanorattle-type or yolk/shell architectures based on a ferrocene-containing polymer precursor is described. Monodisperse nanorattle-type magnetic particles are obtained by using convenient semicontinuous emulsion polymerization and Stöber process protocols followed by thermal treatment. The particles are characterized by TGA, TEM, WAXS, DLS, XPS, and Raman spectroscopy. Herein, established synthetic protocols widen opportunities for the convenient bottom-up strategies of various ferrocene-precursor-based spherical architectures for advanced ceramics with potential applications within fields of sensing and stimuli-responsive nanophotonics.

Sandwich complex-containing macromolecules: property tunability through versatile synthesis

Sandwich complexes feature unique properties as the physical and electronic properties of a hydrocarbon ligand or its derivative are integrated into the physical, electronic, magnetic, and optical properties of a metal. Incorporation of these complexes into macromolecules results in intriguing physical, electrical, and optical properties that were hitherto unknown in organic-based macromolecules. These properties are tunable through well-designed synthetic strategies. This review surveys many of the synthetic approaches that have resulted in tuning the properties of sandwich complex-containing macromolecules. While the past two decades have seen an ever-growing number of research publications in this field, gaps remain to be filled. Thus, we expect this review to stimulate research interest towards bridging these gaps, which include the insolubility of some of these macromolecules as well as expanding the scope of the sandwich complexes.

Organometallic Routes into the Nanorealms of Binary Fe-Si Phases

The Fe-Si binary system provides several iron silicides that have varied and exceptional material properties with applications in the electronic industry. The well known Fe-Si binary silicides are Fe₃Si, Fe₅Si₃, FeSi, α-FeSi₂ and β-FeSi₂. While the iron-rich silicides Fe₃Si and Fe₅Si₃ are known to be room temperature ferromagnets, the stoichiometric FeSi is the only known transition metal Kondo insulator. Furthermore, Fe₅Si₃ has also been demonstrated to exhibit giant magnetoresistance (GMR). The silicon-rich β-FeSi₂ is a direct band gap material usable in light emitting diode (LED) applications. Typically, these silicides are synthesized by traditional solid-state reactions or by ion beam-induced mixing (IBM) of alternating metal and silicon layers. Alternatively, the utilization of organometallic compounds with reactive transition metal (Fe)-carbon bonds has opened various routes for the preparation of these silicides and the silicon-stabilized bcc- and fcc-Fe phases contained in the Fe-Si binary phase diagram. The unique interfacial interactions of carbon with the Fe and Si components have resulted in the preferential formation of nanoscale versions of these materials. This review will discuss such reactions.

Nanostructured magnetic thin films from organometallic block copolymers: pyrolysis of self-assembled polystyrene-block-poly(ferrocenylethylmethylsilane)

The pyrolysis of cylinder-forming samples of the diblock copolymer polystyrene-block-poly(ferrocenylethylmethylsilane) (PS-b-PFEMS) in bulk and in thin films has confirmed that these materials are useful for the generation of semi-ordered arrays of C/SiC ceramics containing Fe nanoparticles which are derived from the organometallic domains. In many cases, the ceramic mass yields were predictable and produced ceramics bearing a monomodal distribution of iron nanoparticles due to the nanoscaled structure of the preceramic PFEMS domains. The pyrolysis of thin films stabilized by cross-linking the PS domains with UV light demonstrated high areal yields, improved shape retention, and the presence of cylinder-centered magnetic nanoparticles.