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Molecular entanglements (left) divide the crystalline and amorphous phases and are similar to the linked points that cause microphase separation in block copolymer (right). Our melt-drawing technique results in periodic arrangement of these phases and replaces the conventional paradigm of “entanglement exclusion for high performance” with the novel “entanglement utilization for high functionality”. In this review, our recent developments for nanostructured membranes using block copolymers and homopolymers are compared and reviewed based on their structural similarities.
This focus review describes that modular and hybrid molecular design approach used to introduce artificial chemical reactive groups into biomolecules or bio-related molecules enable the semi-rational construction of stimuli-responsive supramolecular systems.
Recent advances in the study of active self-assembly utilizing biomolecular motors are reviewed. Various methodologies developed for demonstrating active self-assembly of biomolecular motors are discussed in detail with an emphasis on the morphological variations of the self-assembled structures.
We have successfully developed easy-to-use and rapid immunosensor devices based on extended-gate type polymer field-effect transistors (PFETs). The designed PFET was operated under low-voltage conditions, being able to apply for the detection of proteins in water. As a consequence, label-free detection of glycoproteins was achieved by the extended-gate PFETs functionalized with monoclonal or polyclonal antibodies. We believe that PFET-based immunoassays will be an attractive platform for on-site monitoring devices in healthcare applications in the near future.
Direct arylation polycondensation has been investigated to develop efficient synthetic methods of conjugated polymers for use in optoelectronic applications. The optimization of reaction conditions achieved high molecular weights and minimal structural defects in the recurring structures. The optimized direct arylation method has several advantages over conventional methods, e.g., fewer synthetic steps, and high-molecular-weight and high-purity polymer. The high-quality polymeric materials exhibited superior performance to those obtained using a conventional method when used in organic photovoltaics and field-effect transistors.
The liquid crystalline (LC) rod-like mesogens preferentially orient normal to the substrate plane due to the excluded volume effect (homeotropic alignment) in side-chain liquid-crystal (SCLC) polymers free-standing films. For in-plane alignment, a homeotropic orientation is unsuitable because the mesogens are in a direction opposite to the in-plane directions. This review focuses on new approaches to induce a random planar orientation in SCLC polymer systems by interface and surface molecular design utilizing a high-density polymer brush structure and surface segregation structures of block copolymers.
Interfacial morphologies and associated processes in multicomponent polymer systems, e.g., block copolymers (BCPs) and polymer blends, are examined using three-dimensional (3D) microscopies. Because of the rich structural information in 3D images, various new types of structural parameters, including chain conformation inside BCPs nanodomains, chain packing frustration in BCPs, Genus etc., can be obtained. The stability and interfacial dynamics are also discussed.
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.
Preparation of Polymer Brushes with Well-Controlled Stereoregularity and Evaluation of Their Functional Properties High-density poly(methyl methacrylate) (PMMA) brushes with well-controlled stereoregularity were prepared using a surface-initiated living anionic polymerization method in the presence of a Lewis acid. A molecular weight range from 6 K to 400 K with a narrow polydispersity index (PDI) was obtained. Grazing incidence wide-angle X-ray diffraction measurements indicated that the polymer brushes formed a helical structure approximately 1 nm in diameter and consisting of encapsulated functional molecules or polymers, leading to the formation of inclusion complexes or stereocomplexes.
A new nucleic acid delivery framework, predicated on a photo-responsive cationic block copolymer (BCP), was used to precisely tune nucleic acid binding and provide spatiotemporal control over gene expression. This innovative platform leveraged a macromolecular design in which the polymer moieties directly responsible for nucleic acid complexation were cleaved from the polymer upon photo-stimulation, significantly enhancing nucleic acid release. Temporal control over polyplex disassembly facilitated development of a potentially universal, kinetic modeling scheme for gene silencing. Furthermore, this versatile BCP-based framework easily accommodated anionic excipients and quantum dot imaging constructs.
Soft materials based on colloidal self-assembly in ionic liquids: fundamental studies on the colloidal stability in ionic liquids (ILs) are highlighted. Three different repulsive forces—electrostatic, solvation, and steric—are examined for their effectiveness to stabilize colloidal particles in ILs. An overview of recent studies on colloidal soft materials in the presence of ILs is also provided. Based on suspended states of colloid particles, two different soft materials—colloidal gel and colloidal glass—were prepared in ILs. Their functional properties, including ionic transport, rheological and optical properties, are discussed in relation to the microstructures of the colloidal materials.
A chromatography-free procedure for the preparation of monodisperse monotosylated PEGs allowed for the preparation of 8- to 16-mers in relatively large quantities in good yields and purities and facilitates the investigation of PEG-based functional molecules such as structured PEGs, which had specific two-dimensional shapes. For example, the triangular molecule dehydrated at a lower temperature than linear compounds with a similar molecular weight and can suppress aggregation of proteins at high temperatures. It was also found that the introduction of an aromatic group in the PEG skeleton lowered the dehydration temperature.
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.
Synthesis and thermal properties of poly(oligomethylene-cyclopentylene)s and poly(oligomethylene-cyclohexylene)s with regulated regio- and stereochemistry are described. Pd complexes with diimine ligands promote controlled isomerization polymerization of 4-alkylcyclopentenes and alkenylcyclohexanes to afford poly(oligomethylene-1,3-cyclopentylene)s with trans structure and poly(oligomethylene-1,4-cyclohexylene)s with trans or cis structure, respectively. Poly(ethylene-1,2-cyclopentylene) with cis and trans-stereochemistry can be obtained by Fe- and Co-catalyzed cyclopolymerization of 1,6-heptadiene, respectively. The thermal properties of the poly(oligomethylene-cyclopentylene)s and poly(oligomethylene-cyclohexylene)s are compared to those of previously reported polymers with different regio- or stereochemistry.
In this focus review, our recent progress on hybrid polymers and supramolecules utilizing silicon and arsenic is overviewed. Novel materials design based on polyhedral oligomeric silsesquioxane (POSS) has been realized by focusing on the symmetry. Practical synthetic methods have opened new avenue to experimental studies on organoarsenic compounds.
In this focus review, our recent investigations into the deformation and fracture processes of crystalline polymers using coarse-grained molecular dynamics simulations are described. The lamellar structure of polyethylene, a fundamental structural feature of this polymer, is successfully reproduced. Then, a stress– strain curve that exhibited good consistency with that observed experimentally is obtained. Molecular simulations are a powerful tool for elucidating the mechanisms of the deformation and fracture processes of crystalline polymers at the molecular level and this review will contribute to the development of this field of research.
The true chiroptical measurements of optically anisotropic samples cannot be generally achieved with modern chiroptical spectrophotometers such as circular dichroism and circularly polarized luminescence based on polarization modulation techniques because of the coupling effect of the nonideal optics and the electronics with macroscopic anisotropies. Artifact signals related to the nonchiral phenomena are often much stronger than the chiroptical signals. Universal chiroptical spectrophotometer (UCS) and comprehensive chiroptical spectrophotometer (CCS) integrated into the Stokes–Mueller matrix analysis for optically anisotropic samples can be applicable for accurate chiroptical measurements for samples with macroscopic anisotropies.
The inclusion of electrically insulating aliphatic spacers between π-conjugated segments of semiconducting polymers represents an emerging and versatile tool to control material properties. Here we review this strategy and highlight recent reports demonstrating the control over chain self-assembly, the tunability of viscosity and elasticity, and the ability to provide insights into inter- and intra-charge transport processes—without detrimental effects on the polymer semiconducting ability. While still at an early stage, this approach gives promise towards engineering optoelectronic performance, melt-processed organic electronics, and applications toward stretchable wearable semiconducting devices.
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.
