Reviews & Analysis

Angle-independent colored materials based on Christiansen effect was successfully prepared using phase-separated polymer membrane and thermotropic liquid crystal. Because this system displays angle-independent color and can act as a multi-color polymer-dispersed liquid crystal, I believe that this system may be applicable for energy-saving multi-color displays.

We demonstrate a new methodology of DNA and RNA functionalization with a base surrogate prepared from d-threoninol. With this surrogate, we can introduce functional molecules at any position in the sequence. Our methodology is conceptually similar to copolymerization; phosphoramidite monomers of base surrogates, and natural nucleotides are ‘copolymerized’ on solid supports to prepare functional oligonucleotides. The incorporation of intercalating moieties allows for the design of four stable functional motifs: wedges, interstrand-wedges, dimers and clusters. By selecting suitable functional molecules and motifs, we can design novel photofunctional oligonucleotides.

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.

In this focused review, we provide an overview of our recent work on the design and synthesis of a new type of side-chain liquid crystal π-conjugated polymeric system associating regioregular poly(3-alkylthiophene) backbones with laterally pending π-conjugated mesogenic groups. Several polymeric architectures have been prepared based on different polymer backbone structures and various side groups, providing important insight into the relationships among the polymeric architecture, nano- and macroscale organization and charge transport properties in such self-organized multi-lamellar macromolecular systems.

Liquid crystals (LCs) have recently gained significant importance in organic photovoltaics (PVs). Power-conversion efficiency up to about 10% has reached in solar cells incorporating LCs. This review presents an overview of the developments in the field of organic PVs with LCs. Comprehensive details of LCs used in bilayer solar cells, bulk heterojunction solar cells and dye-sensitized solar cells have been given. An outlook into the future of this newly emerging, fascinating and exciting field of self-organizing supramolecular LC PV research is provided.

The state-of-the-art atomic force microscopy allows us to observe inner structures of single molecules. Such observation is quite beneficial to study single and self-assembled molecules on surface as well as on-surface chemical reaction. This focus review describes recent technical improvement and achievements in the field of on-surface molecule studied with high-resolution atomic force microscopy.

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.

Liquid crystalline organic semiconductors are good candidates for organic transistors because the materials have properties that are beneficial compared with those of polymer materials. Liquid crystalline materials show good solution processability for the fabrication of uniform crystalline thin films. The novel liquid crystalline material 2-phenyl-7-decyl[1]benzothieno[3,2-b][1]benzothiophene (Ph-BTBT-10) exhibits a highly ordered liquid crystal phase, and has good solution processability and high thermal durability to use for creating transistor devices with high mobility, over 10 cm² Vs⁻¹, following thermal annealing.

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-C_x-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.

Perylene tetracarboxylic bisimide (PTCBI) derivatives bearing oligosiloxane moieties were synthesized. At room temperature, the PTCBI derivatives bearing oligosiloxane chains exhibit a nanosegregated columnar phase in which crystal-like π-stacks are surrounded by a liquid-like mantle. These PTCBI derivatives are soluble in various organic solvents, and thin films can be produced by a spin-coating method. The PTCBI derivatives bearing polymerizable cyclotetrasiloxane rings show the liquid crystalline (LC) phases at room temperature. The spin-coated films of the LC PTCBI derivatives with cyclotetrasiloxane rings can be polymerized and insolubilized by exposure to the vapors of trifluoromethanesulfonic acid.

Various conjugated polymers self-assemble to form well-defined microspheres that act as optical resonators. Upon focused laser irradiation, the single isolated microspheres exhibit whispering gallery mode photoluminescence (PL), where sharp and periodic emission lines appear in the PL spectra. Efficient and long-range intersphere light energy transfer is demonstrated using coupled microspheres. Conjugated polymer microspheres are advantageous as optical resonators in terms of their high refractive index, photoabsorptivity, and PL efficiency, as well as simple and low-energy fabrication processes, beneficial for the practical application.

The adhesion of hydrogels has attracted attention for use in building three-dimensional (3D) constructs, such as scaffolds for cell culture, carriers of drug release system and soft actuators. Electrophoretic hydrogel adhesion, which is the electrophoretic manipulation of a polyelectrolyte to form an adhesive layer at the interface of two gels, was developed. To apply this adhesive method to build 3D materials, rapid and free-form fabrication of hydrogel constructs was achieved by the electrophoretic adhesion of microgels. The development of a novel adhesion strategy will be useful for the fabrication of novel 3D hydrogel architectures.

Biodegradable aliphatic carbonyl polymers, such as polylactides, polylactones and polycarbonates, have been studied for applications in a broad range of resorbable medical devices. This review mainly highlights the synthesis and application of poly(trimethylene carbonate) (PTMC) analogs with various substituents derived from 2,2-bis(methylol)propionic acid. In addition, organocatalytic transesterification is discussed as an indispensable tool for further functionalization and sophistication of the PTMC analogs.

Silkworms produce silk fibroin fiber from an aqueous silk fibroin solution by applying shear stress within the spinneret at ambient temperature. Here the structures of silk fibroin before and after spinning determined by solution and solid-state nuclear magnetic resonance. The solution structure was determined by using native liquid silk extracted from silkworm larvae and the lamellar structure of fibroin after spinning was determined. Moreover, a silk-based small diameter vascular graft was developed by electrospinning. These studies provide a perspective for investigations of energy-conserving fiber processing techniques and silk-based biomedical materials.

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.

This review focuses on the factors that determine the molecular weight of polyhydroxyalkanoate (PHA), an aliphatic polyester synthesized by bacteria for carbon and energy storage. Because the mechanical strength of PHA increases with its molecular weight, high-molecular weight PHA polymers are preferred. The synthesis of high-molecular weight PHA should consider the following factors: the concentration of PHA synthase, occurrence of chain transfer reaction, catalytic activity of PHA synthase and simultaneous degradation of PHA during biosynthesis. These factors have a direct impact on the molecular weight of PHA.

Vibrational circular dichroism (VCD) is effective for analyzing the configuration and conformation of various bio(macro)molecules. In addition to a conventional VCD approach using theoretical calculations, this review explains how the use of an exciton-type VCD couplet can be employed to elucidate the structures of bio(macro)molecules, such as carbohydrates, glycerophospholipids, proteins and polyesters.

This review focuses on supramolecular gelation that exhibits unique optical functionality through the highly ordered aggregation of low-molecular-weight compounds. The supramolecular gels can be applied to improve the functionality of polymer materials through nanofibrillar network formation, while maintaining transparency. We discuss concepts and methods for manufacturing supramolecular gels, their optical characteristics and their applications for light management technology.

In this focus review, we overview our recent works on acyclic artificial nucleic acids (XNAs). Three acyclic XNAs, D-aTNA, SNA and L-aTNA have been developed. D-aTNA can form extremely stable homo-duplex, whereas it shows a high orthogonality with natural nucleic acids. SNA oligomers can change their helicity and chirality depending on sequences. L-aTNA can form stable duplexes with both DNA and RNA. Owing to unique properties of these XNAs, they should find application as tools in biology, biotechnology and nanotechnology.

This report reviews the seminal features and characteristics of free-standing polymeric ultrathin films (nanosheets), including fabrication methods, mechanical properties and biomedical and health-care applications (for example, wound dressings, tissue engineering materials and bioelectronic devices). ‘Nanosheet technology’ is a promising approach for the development of advanced medical applications and health-care practices in surgery and regenerative medicine, as well as for connecting the human body to electronic interfaces for future medical applications.