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Stretchable electronics are an attractive means for producing mechanically robust devices with enhanced utility and can enable novel applications such as conformal solar cells, electronic skin and wearable electronics. Approaches to stretchable organic electronics, specifically polymer solar cell active layer materials, via a molecular design strategy are presented. Further discussion into polymer blends and engineering approaches to producing other types of stretchable electronics is given. The relationships between mechanical and electrical properties of all these materials are discussed and suggestions are given for future areas of research.
Developing renewable polymeric materials for electronics applications is crucial toward next generation of green electronic industry. Current progress on the renewable materials used as the passive and active components in electronics is reviewed, where the correlation between the relationships of chemical structures, morphology and device characteristics is featured. Furthermore, their future perspectives are provided for foreseeable paths in the development of green electronics.
A series of dioxocycloalkene-annelated thiophenes was designed to utilize as noble acceptor units in donor–acceptor (D–A) copolymers, and D–A copolymers containing these acceptor units were systematically developed for the application to organic photovoltaics (OPVs). Photophysical and electrochemical properties of these copolymers as well as their photovoltaic performance under the combination with [6,6]-phenyl-Cx-butyric acid methyl ester (x=61 or 71) were summarized. These systematic investigations provide important clues for the development of high-performance D–A-type OPV materials.
In this focus review, alternating copolymers of carbon dioxide with epoxides have been synthesized and studied as novel ion-conductive polymers. The Li salt electrolytes of poly(ethylene carbonate) (PEC) and of other polycarbonates having different side groups exhibited remarkable ion-conductive properties including the following: increased conductivity with increasingly higher salt concentrations, very high values for the Li+ transference number, and good electrochemical stability. The Li-ion conductivity of a highly concentrated PEC-LiFSI electrolyte was estimated to be greater than 10−4 S cm−1, and excellent battery performance was demonstrated at room temperature.
By interaction between light and structural periodicity, structural coloration is caused. The artificially periodic materials are called photonic crystals and it has attracted great attention for optical applications. Recently, we prepared one-dimensional photonic crystal with multibilayered films consisting of azobenzene-containing polymers and polyvinyl alcohol and reported the on–off switching controlled by refractive index change depended on the molecular orientation states. In addition, we studied the birefringence properties of azobenzene-containing polymers based on their molecular design for the improvement of the switching speed and reflection intensity of photonic crystals.
The recent progress of our research on proton exchange membranes for fuel cell applications is reviewed. In particular, we have focused on the effect of the molecular structures of fluorine-free sulfonated aromatic polymers on membrane properties (e.g., proton conductivity, chemical and mechanical stability). We identified an optimized hydrophilic molecular design (sulfophenylene as SPP), that is, SPP simultaneously exhibited the highest proton conductivity and excellent mechanical stability over a wide range of humidities.
Hydrogel microspheres (microgels) are composed of crosslinked hydrophilic or amphiphilic polymer chains and exhibit fascinating properties. Their typical size range (<~10 μm) and their excellent properties promise a variety of attractive applications as for example templates, microreactors, catalysts, coatings, and drug carriers. Against this background, we have conducted systematic research on microgels including their synthesis, characterization, assembly, and applications. In this focus review, we summarize recent results of microgel research mainly from our group and those of our collaborators.
Our recent studies on the nano- and micro-structured molecule-responsive hydrogels are summarized. The nano- and micro-structured molecule-responsive hydrogels exhibited rapid swelling/shrinkage behavior in response to a target molecule based on the association/dissociation of molecular complexes that act as crosslinkers. In addition, these hydrogels showed smart functions, such as autonomous molecule-responsive microchannel flow regulation and highly sensitive detection of a target molecule. The smart functions of nano- and micro-structured molecule-responsive hydrogels can provide tools for constructing sensors, microdevices and smart biomaterials.
Incorporating additional electron donors or acceptors into conjugated D–A alternating polymers result in various conjugated D–A terpolymers. The presence of additional electron donors or acceptors can modulate their electronic absorptions, highest occupied molecular orbital/lowest unoccupied molecular orbital levels as well as interchain interactions and thin-film morphologies. Because of these structural features, conjugated D–A terpolymers have been intensively investigated for applications in field-effect transistors and photovoltaic cells. In this review, we introduce recent developments of conjugated D–A terpolymers with various combinations of electron donors and acceptors, and discuss the future perspectives of them.
We review our recent studies on material designs based on element-blocks, which are defined as a minimum functional unit composed of heteroatoms, and particularly focus on the roles of element-blocks in these materials. To start, the development of ‘designable hybrids’ by employing polyhedral oligomeric silsesquioxane is illustrated. The following topics include solid-state luminescent materials containing o-carborane and group 13 element-blocks. Their highly efficient emission in the solid state and their photochemistry are explained. Furthermore, we mention chiral element-blocks containing optically active phosphine atoms. The unique properties of this series of element-block materials are illustrated.
A focused review of photoresist strategies that have been studied over the past few decades driven by the demands of Moore’s law. Selected results are discussed with emphasis on the choice of photoresist chemistry depending on the particulars of each radiation type or patterning strategy, while we present special architectures of photoresists that have attracted a great interest in the semiconductor field.
Organic polymers for hydrogen storage and their molecular design were reviewed. Porous organic polymers reversibly stored and released hydrogen through hydrogen physisorption on their highly porous structures. Polymers containing ketone or N-heterocycle groups fixed and stored hydrogen under atmospheric pressure through the formation of chemical bonds: the hydrogenated polymers released hydrogen in the presence of catalysts at mild conditions. The advantages of the polymers enable easy handling and provide portable hydrogen-carrying materials for use in, for example, a home/on-site or pocketable hydrogen-supply system.
This review focuses on our novel approaches for developing functional polymers by dissociation phenomena of macromolecular complexes. One is highly swellable polymer gels, superabsorbent polymers for nonpolar organic solvents, and the other is thermo-responsive polymers at ambient temperature in nonpolar solvents. Both of them are well-known in water, but no design has ever been proposed for other media. The dissociation of the macromolecular complexes plays a key role for them. Therefore, controlling the dissociation processes in supramolecular chemistry should be another important strategy for emerged dynamic functions.
This review focuses on recent developments in the study of photosensitive engineering plastics based on reaction development patterning (RDP). RDP is a method of forming a fine pattern by promoting the reaction between carboxylic acid derivatives in a polymer chain and nucleophiles in a developer selectively at the exposed or unexposed area. Since engineering plastics such as polyimide and polycarbonate inherently have carboxylic acid derivative groups, RDP can impart photosensitivity to various polymers, including commercially available engineering plastics. Both positive- and negative-tone patterns can be formed by using RDP.
A recent progress of phenanthro[1,2-b:8,7-b′]dithiophene (PDT)-based low bandgap semiconducting polymers combined with various strong acceptor units are described. By incorporating a highly π-extended PDT core into the polymer backbone, the synthesized polymers have deep HOMO energy levels and formed a dense packing structure with a short π-stacking distance. The PDT-based polymers with optimal side chains and high molecular weight exhibit high hole mobility of up to 0.18 cm−1 V−1 s−1 in organic field-effect transistors and high power conversion efficiency over 6%. These results indicate that PDT is a good π-framework as high-performance semiconducting polymers.
This review summarizes the recent advances in surface-coated single-walled carbon nanotubes as near-infrared nanometer-sized photoluminescent emitters for single-particle imaging and tracking applications in complex biological environments. It is focused on demonstrating surface coating identification, excitation strategies comparison, and long-term single-nanotube tracking inside the brain extracellular space in the live brain tissue.
Open-shell organic semiconductors are poised to enable new functions and applications ranging from electronics and optoelectronics to magneto-electronics. Here, we review strategies toward molecular magnets or spin–polarized magnetic organic semiconductors that encompasses incorporation of stable radical groups directly into the backbone of organic semiconductors or preparation of highly conjugated ladder-type molecules based on open–shell Kekulé–type structures to enable efficient spin delocalization/spin-transfer along the conjugation length. We briefly survey the history of this field, summarize recent developments, and set an outlook for the future.
This review deals with the synthesis of various polymers carrying bulky and rigid adamantyl substituents in the side chain. The synthetic methods of those polymers include the typical polymer reaction by introducing adamantyl groups to the present polymers and the polymerization of the monomers bearing the adamantyl pendant groups. A variety of vinyl monomers, such as styrenes, 1,3-butadiene, and (meth)acrylates, are capable of the living anionic polymerization to afford the polymers having predictable molecular weights and narrow molecular weight distributions (Mw/Mn =1.1). The resulting adamantyl-substituted polymers show extremely high glass transition temperatures and high thermal stability derived from the stiff adamantyl substituents compared with the corresponding parent polymers.
Among various approaches to create self-healing polymers, the introduction of dynamic bonds to polymers is one of the most powerful approaches. However, since the reformation of dynamic bonds requires molecular mobility, mechanical strength usually conflicts with an autonomous healing ability. In this review, we overview recent successful approaches to overcome this limitation, as well as attempts to design mechanically robust polymers that can heal with the assistance of ubiquitous stimuli. These approaches include combining careful dynamic bond chemistry choices and smart designs of the environment around the dynamic bonds.
Flavin catalysts are typically metal-free, and their catalytic activity can be readily accessed using mild terminal oxidants such as H2O2 and O2; therefore, redox reactions with these compounds have great promise as alternatives to reactions with conventional metal catalysts for the sustainable production of important chemicals. Herein, our recent research on flavin catalysts including the development of facile preparation methods for flavin catalysts using polymers, readily reusable polymer-supported flavin catalysts, and flavin-peptide-polymer hybrids that can catalyze the first flavoenzyme-mimetic aerobic oxygenation reactions is summarized.
This focus review addresses recent progress on plant oil-based functional polymers and composites. An environmentally benign coating system is demonstrated using plant oils as the starting substrate for the preparation of artificial urushi with high hardness and a high gloss surface. Epoxidized plant oils are polymerized with designed inorganics, cellulose, and biodegradable aliphatic polyesters to afford functional biobased polymers and composites. Castor oil is used as the core of branched poly(lactic acid) to improve the physical properties of biobased plastics.
