Recent Advances in Conjugated Transition Metal-containing Polymers and Materials

Metal-containing conjugated oligomers and polymers are reviewed, focusing on the work carried out by the author and coworkers since 1995. The synthesis of model systems, electropolymerizable monomers and polymer films are discussed, along with the electronic and spectroscopic properties of these systems. The application of phosphino-oligothiophene ligands as an entry to conjugated metallopolymers is described.     

High-Performance Directional Metallopolyamides. II. Optical Spectroscopic Studies of Metal Chelation

The chelating interaction between metal ions and 4,4-disubstituted-2,2-bipyridyl-containing high-performance polymeric ligands prepared from 2,2-bipyridyl-4,4-dicarboxylic acid and a series of primary aromatic diamines was investigated by optical spectroscopy. Optical spectroscopic studies of the chelation of ruthenium ions by the 2,2-bipyridyl-containing polyamides revealed the formation of distinct ruthenium(II) complexes [Ru^II(poly)L₄] ( _max=530 nm), [Ru^II(poly)₂L₂] ( _max=584 nm), and [Ru^II(poly)₃]²⁺ ( _max=476 nm), while iron(II) ions formed only one complex ( _max=569 nm). The diverse functional features of the polymer repeat unit directly influences the chelation of metal ions.     

Nanofabrication with metallopolymers ‐ recent developments and future perspectives

Synthetic polymers containing metals and metal centers have experienced rapid growth in the last two decades. Metal‐containing polymers have an unprecedented role to play in modern high‐tech applications including nanomanufacturing, sensing, separation and catalysis. Advancement in synthetic strategies for macromolecules has enabled the synthesis of novel, exotic and use‐inspired metallopolymers. Using state‐of‐the‐art design strategies, it is now possible to perform targeted synthesis of macromolecules with varied complexity that contain a range of metal centers either in the backbone or in the side chains of the organic moiety. The presence of an inorganic element (metals and metal centers) in organic moieties has led to a number of new physicochemical properties while implementing novel functionality to the polymer matrix. This review covers nanotechnology influenced by distinctive features of metal‐containing macromolecular systems, particularly in developing flexible, functional materials. © 2013 Society of Chemical Industry     

Facile Generation of L10‐FePt Nanodot Arrays from a Nanopatterned Metallopolymer Blend of Iron and Platinum Homopolymers

Hard ferromagnetic (L1₀ phase) FePt alloy nanoparticles (NPs) with extremely high magnetocrystalline anisotropy are considered to be one of the most promising candidates for the next generation of ultrahigh‐density data storage system. The question of how to generate ordered patterns of L1₀‐FePt NPs and how to transform the technology for practical applications represents a key current challenge. Here the direct synthesis of L1₀ phase FePt NPs by pyrolysis of Fe‐containing and Pt‐containing metallopolymer blend without post‐annealing treatment is reported. Rapid single‐step fabrication of large‐area nanodot arrays (periodicity of 500 nm) of L1₀‐ordered FePt NPs can also be achieved by employing the metallopolymer blend, which possesses excellent solubility in most organic solvents and good solution processability, as the precursor through nanoimprint lithography (NIL). Magnetic force microscopy (MFM) imaging of the nanodot pattern indicates that the patterned L1₀ phase FePt NPs are capable of exhibiting decent magnetic response, which suggests a great potential to be utilized directly in the fabrication of bit patterned media (BPM) for the next generation of magnetic recording technology.     

Metal‐containing Polymers via Electropolymerization

Electropolymerization represents a suitable and well‐established approach for the assembly of polymer structures, in particular with regard to the formation of thin, insoluble films. Utilization of monomers that are functionalized with metal complex units allows the combination of structural and functional benefits of polymers and metal moieties. Since a broad range of both electropolymerizable monomers and metal complexes are available, various structures and, thus, applications are possible. Recent developments in the field of synthesis and potential applications of metal‐functionalized polymers obtained via electropolymerization are presented, highlighting the significant advances in this field of research.     

Metallopolymer Organohydrogels with Photo-Controlled Coordination Crosslinks Work Properly Below 0 °C

Controlling the structures and functions of gels is important for both fundamental research and technological applications. Introducing photoresponsive units into gels enables remote control of their properties with light. However, existing gels show photoresponsiveness only at room temperature or elevated temperatures. The development of photoresponsive gels that work below 0 °C can expand their usage in cold environments. Here, photoresponsive metallopolymer organohydrogels that function even at −20 °C are reported. The organohydrogels are prepared using photoresponsive Ru–thioether coordination bonds as reversible crosslinks to form polymer networks. A water/glycerol mixture is used as an anti-freezing solvent. At −20 °C, the Ru–thioether coordination bonds are dissociated under light irradiation and reformed reversibly in the dark, which result in alternating crosslinking densities in the polymer networks. This process enables inducing reversible gel-to-sol transitions, healing damaged gels, controlling the mechanical properties and volumes of the gels, and rewriting microstructures on the gels below 0 °C.     

Recent Advances in Luminescent Transition Metal Polyyne Polymers

This review briefly summarizes research work carried out by the author in the past decade on rigid-rod transition metal polyyne polymers and their molecular precursors. The research involves the synthesis, spectroscopic and photophysical characterization, ligand functionalization, and possible optoelectronic applications of transition metal polyyne polymers. Herein, oligomeric and polymeric metal alkynyl systems of the late transition metals are discussed, and particular attention is focused on the electronic absorption spectroscopy and photoluminescence behavior, thermal stability and structural aspects of these polymetallaynes. A detailed account of the evolution of the first excited singlet and triplet state on the electronic structure of the organic spacer groups of these metal polyyne polymers is also given and the interplaying factors that govern the spatial extent of the lowest-lying singlet and triplet energy levels for the chemical tailoring of the singlet–triplet gap are elucidated. The possible developments of this research are also envisaged.     

Polymer‐Modified Mesoporous Silica Thin Films for Redox‐Mediated Selective Membrane Gating

Controlling structure and function to switch ionic transport through synthetic membranes is a major challenge in the fabrication of functional nanodevices. Here we describe the combination of mesoporous silica thin films as structural unit, functionalized with two different redox‐responsive ferrocene‐containing polymers, polyvinylferrocene (PVFc) and poly(2‐(methacryloyloxy)ethyl ferrocenecarboxylate) (PFcMA), by using either a grafting to, or a grafting from approach. Both mesoporous film functionalization strategies are investigated in terms of polymer effect on ionic permselectivity. A significantly different ionic permselective behavior can be observed. This is attributed to different polymer location within the mesoporous film, depending on the functionalization strategies used. Additionally, the influence of chemical oxidation on the ionic permselective behavior is studied by cyclic voltammetry showing a redox‐controlled membrane gating as function of polymer location and the pH value. This study is a first step of combining redox‐responsive ferrocene‐containing polymers and mesoporous membranes, and thus towards redox‐controlled ionic transport through nanopores.     

Intrinsic high refractive index polymers

As the ubiquity and complexity of optical devices grows, our technology becomes more dependent on specialized functional materials. One area of continued interest is in high refractive index polymers as lightweight, processable and inexpensive alternatives to silicon and glass. In addition to a high refractive index, optical applications require these polymers to be transparent and have a low optical dispersion. Both nanocomposite and intrinsic high refractive index polymers offer particular advantages and disadvantages. While nanocomposite high refractive index polymers have refractive indices above 1.80, the nanoparticle type, content and size can negatively affect storage stability and processability. Alternatively, intrinsic high refractive index polymers are prepared by introducing an atom or substituent with a high molar refraction into a polymer chain; the resultant polymers are easier to store, transport, tune and process. Polymers containing aromatic groups, halogens (except fluorine), phosphorus, silicon, fullerenes and organometallic moieties have all shown significant promise. Many factors can affect intrinsic high refractive index polymer performance including molecular packing, molar volume, chain flexibility and substituent content. This mini‐review summarizes the principles behind and recent developments in intrinsic high refractive index polymers. © 2014 Society of Chemical Industry