Polyferrocenes are

polymers A polymer () is a substance or material that consists of very large molecules, or macromolecules, that are constituted by many repeating subunits derived from one or more species of monomers. Due to their broad spectrum of properties, b ...

containing

ferrocene Ferrocene is an organometallic chemistry, organometallic compound with the formula . The molecule is a Cyclopentadienyl complex, complex consisting of two Cyclopentadienyl anion, cyclopentadienyl rings sandwiching a central iron atom. It is an o ...

units. Ferrocene offers many advantages over pure

hydrocarbons In organic chemistry, a hydrocarbon is an organic compound consisting entirely of hydrogen and carbon. Hydrocarbons are examples of group 14 hydrides. Hydrocarbons are generally colourless and hydrophobic; their odor is usually faint, and may b ...

when used as a building block of

macromolecular chemistry A macromolecule is a "molecule of high relative molecular mass, the structure of which essentially comprises the multiple repetition of units derived, actually or conceptually, from molecules of low relative molecular mass." Polymers are physi ...

. The variety of possible substitutions at the ferrocene parent body results in a multitude of accessible polymers with interesting electronic and photonic properties. Many polyferrocenes are relatively easily accessible. Poly(1,1'-ferrocene-silane) can be prepared by

ring-opening polymerization In polymer chemistry, ring-opening polymerization (ROP) is a form of chain-growth polymerization in which the terminus of a polymer chain attacks cyclic monomers to form a longer polymer (see figure). The reactive center can be radical, anion ...

and has a variety of interesting properties, such as a high

refractive index In optics, the refractive index (or refraction index) of an optical medium is the ratio of the apparent speed of light in the air or vacuum to the speed in the medium. The refractive index determines how much the path of light is bent, or refrac ...

semiconductor properties A semiconductor is a material with electrical conductivity between that of a conductor and an insulator. Its conductivity can be modified by adding impurities (" doping") to its crystal structure. When two regions with different doping levels ...

Ring-opening polymerization In polymer chemistry, ring-opening polymerization (ROP) is a form of chain-growth polymerization in which the terminus of a polymer chain attacks cyclic monomers to form a longer polymer (see figure). The reactive center can be radical, anion ...

usually leads to polymers containing ferrocene in the backbone. Besides the latter motif, ferrocene can be attached to the backbone as pendant unit as well.Rudolf Pietschnig: ''Polymers with pendant ferrocenes.'' In: ''Chemical Society Reviews.'' 45, 2016, S. 5216, . Biferrocene

Potential applications

Polyferrocenes currently have no commercial applications, despite being the subject of research for nearly 50 years. Poly vinylferrocene gives electroactive films that have been investigated as glucose sensors.

Coatings

Satellites A satellite or an artificial satellite is an object, typically a spacecraft, placed into orbit around a celestial body. They have a variety of uses, including communication relay, weather forecasting, navigation ( GPS), broadcasting, scientif ...

charge themselves by the bombardment with charged particles of the

solar wind The solar wind is a stream of charged particles released from the Sun's outermost atmospheric layer, the Stellar corona, corona. This Plasma (physics), plasma mostly consists of electrons, protons and alpha particles with kinetic energy betwee ...

. Charging can lead to an

arc discharge An electric arc (or arc discharge) is an electrical breakdown of a gas that produces a prolonged electrical discharge. The current through a normally nonconductive medium such as air produces a plasma, which may produce visible light. An ...

which can impair the function of the satellite due to magnetic disturbances and material failure. To avoid these impairments, coatings of electrically weak or non-conductive plastic components of thin films of poly(1,1'-ferrocen-silane) were examined. These carry off the charge generated by the irradiation and thus could protect the satellite from overloads. R. Resendes, A. Berenbaum, G. Stojevic, F. Jäkle, A. Bartole, F. Zamanian, I. Manners: ''Application of ring-opened poly(ferrocene)s as protective charge dissipation coatings for dielectrics''. In: ''Advanced Materials'', 12(5), (2000), S. 327-330, .

Polymers with high refractive index

Polyferroccenes have attracted interest as

high-refractive-index polymer A high-refractive-index polymer (HRIP) is a polymer that has a refractive index greater than 1.50. Such materials are required for anti-reflective coating and photonic devices such as light emitting diodes (LEDs) and image sensors. The refractive ...

s, such as in antireflection coatings or for

light-emitting diodes A light-emitting diode (LED) is a semiconductor device that emits light when current flows through it. Electrons in the semiconductor recombine with electron holes, releasing energy in the form of photons. The color of the light (corresp ...

.Ian Manners: ''Polyferrocenylsilanes: metallopolymers for electronic and photonic applications.'' In: ''Journal of Optics A: Pure and Applied Optics.'' 4, 2002, S. S221, . Poly(1,1'-ferrocene-silane)e, poly(1,1'-ferrocene-phosphane) and polyferrocenes with phenyl side chains are polymers with unusually high refractive index, with values in the refractive index of up to 1.74. These polyferrocenes show good film-forming ability.Vasilios Bellas, Matthias Rehahn: ''Polyferrocenylsilane-Based Polymer Systems.'' In: ''Angewandte Chemie International Edition.'' 46, 2007, S. 5082, .

Plasma-assisted reactive ion etching

Poly(ferrocene-dimethylsilane)s (PFS) are promising as barrier materials in plasma-assisted reactive ion etching. Due to the presence of

iron Iron is a chemical element; it has symbol Fe () and atomic number 26. It is a metal that belongs to the first transition series and group 8 of the periodic table. It is, by mass, the most common element on Earth, forming much of Earth's o ...

and

silicon Silicon is a chemical element; it has symbol Si and atomic number 14. It is a hard, brittle crystalline solid with a blue-grey metallic lustre, and is a tetravalent metalloid (sometimes considered a non-metal) and semiconductor. It is a membe ...

in the main chain, the polymer proved to be relatively stable compared to purely organic polymers. During the etching, a thin iron and silicon-containing oxide layer was formed on the surface of the poly(ferrocene-dimethylsilane).Rob G. H. Lammertink, Mark A. Hempenius, Vanessa Z.-H. Chan, Edwin L. Thomas, G. Julius Vancso: ''Poly(ferrocenyldimethylsilanes) for Reactive Ion Etch Barrier Applications.'' In: ''Chemistry of Materials.'' 13, 2001, S. 429, .

References

External links