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  • With recent advancements in the Internet of Things (IoT), indoor organic photovoltaic devices (iOPVs) have attracted increasing attention because of their potential utility as self-sustainable, eco-friendly power sources. This review highlights emerging iOPV technologies based on π-conjugated polymers and oligomeric materials and outlines their fundamental principles and characterization techniques.

    • Sunbin Hwang
    • Takuma Yasuda
    Review Open Access
  • Chemical design strategies developed in the last decade for conjugated polymer binders in lithium-ion batteries (LIBs) are reviewed here. The first part of this review discusses the mechanism of operation and role of binders in LIBs, and the importance of conductivity in advanced binder systems. The second part of this review gives an account of various conducting polymer binders developed for cathodes and anodes of LIBs. The review concludes with an emphasis on sustainable synthetic design strategies for next-generation conducting polymer binders for greener electrochemical energy storage systems.

    • Pratyusha Das
    • Barry C. Thompson
  • This review is focused on evolutions of precision radical polymerizations in various directions from metal-catalyzed Kharasch addition or atom transfer radical addition (ATRA). The developments include metal-catalyzed living radical polymerizations via reversible activation of carbon-halogen bonds, metal-catalyzed step-growth radical polymerizations of designed monomers having an unconjugated vinyl group and a reactive carbon-halogen bond, simultaneous metal-catalyzed chain- and step-growth radical polymerization for producing degradable vinyl copolymers with main-chain ester units, and vinyl monomer sequence control via combinations of iterative ATRAs and various controlled polymerizations.

    • Masami Kamigaito
  • Academia and industry are interested in using autotrophic microorganisms as a sustainable/green production platform to produce biochemical products and commercially relevant commodities, including biopolymers. Unlike heterotrophs that require carbohydrates and amino acids for growth, autotrophs have evolved to fix carbon dioxide and drive metabolic processes utilizing either light (photoautotrophs) or chemical compounds (chemolithotrophs) as energy sources. Here, we review the current state-of-the-art in the construction of autotrophic microbial cell factories for efficient biopolymer production and recent breakthroughs in natural autotrophs focusing on biopolymer production.

    • Pisanee Srisawat
    • Mieko Higuchi-Takeuchi
    • Keiji Numata
    Review Open Access
  • In 1996, the author reported “self-oscillating” polymer gels that spontaneously repeat swelling–deswelling changes in a closed solution without any on–off switching by external stimuli, such as with heart muscle. The gel has an energy converting system provided by an oscillatory chemical reaction called the Belousov–Zhabotinsky (BZ) reaction, which induces periodic mechanical motion of the polymer chain. The author systematically developed self-oscillating polymer gels with approaches ranging from demonstrating fundamental behaviors to constructing material systems for potential applications in biomimetic materials such as autonomous soft actuators, automatic transport systems, and functional fluids causing autonomous sol-gel oscillations, as seen with amebas. In this review, these research developments and recent progress from the author’s group are summarized.

    • Ryo Yoshida
  • In this review, we overview the recent advances associated with seminal findings in the development of nucleic acid-based fluorescent sensor systems aimed at application for exploring intracellular phenomena. We described the fluorescence signal generation mechanisms of each nucleic acid-based fluorescent sensor, including molecular beacon and quencher-free linear probes, as well as aptamer or DNAzyme-based systems. In addition, cascade hybridization chain reaction and catalyzed hairpin assembly are introduced as methods for amplifying fluorescence signals under isothermal conditions.

    • Aya Shibata
    • Sayuri L. Higashi
    • Masato Ikeda
  • Research advances in the extraction, structural and conformational characteristics, and biological activities (antitumor, anti-inflammation, immunomodulatory, hypoglycemic activity) of β-glucans from three fungi, Auricularia auricula judae, Lentinus edodes and yeast, as typical representatives, were reviewed, as well as the potential mechanism and the structure-function relationship. Additionally, as-fabricated β-glucan-derived nanocomposite biomaterials as carriers for delivering drugs, genes, nanoparticles, and fluorescence probes were addressed.

    • Huanhuan Chen
    • Ningyue Liu
    • Xiaojuan Xu
  • The present review focuses on the enzymatic synthesis of unnatural oligosaccharides and polysaccharides linked through strictly controlled α(1→4)-glycosidic linkages by glucan phosphorylase (GP) catalysis. In particular, the recent progress of the enzymatic synthesis of unnatural polysaccharides by GP (isolated from thermophilic bacteria, Aquifex aeolicus VF5)-catalyzed polymerization and related reactions is overviewed. The unnatural substrates have high applicability as practical functional materials in pharmaceutical, medicinal, and biological research fields.

    • Jun-ichi Kadokawa
  • Hydrophobically modified polysaccharides have attracted considerable attention in the biomedical field because of their biocompatibility, biodegradability, and nontoxicity. This article reviews previous studies on micellar structures formed by hydrophobically modified polysaccharides (pullulan and amylose) in aqueous solutions by static and dynamic light scattering, small angle X-ray and neutron scattering, and fluorescence from pyrene solubilized in the polymer solution. Depending on the degree of substitution, the hydrophobically modified polysaccharides exist in aqueous solution as full or loose flower necklaces or as nanogels made up of randomly branched polymers.

    • Takahiro Sato
    • Jia Yang
    • Ken Terao
  • TEMPO-catalyzed oxidation enables efficient and position-selective conversion of primary hydroxy groups in water-soluble and -insoluble polysaccharides to sodium carboxylate groups. TEMPO/NaBr/NaClO in water at pH 10 is an advantageous system in terms of the degrees of oxidation and reaction rates. Various new water-soluble TEMPO-oxidized polysaccharides have been prepared by TEMPO-catalyzed oxidation, and they have unique properties and functionalities. When crystalline native cellulose and chitin are oxidized by the TEMPO/NaBr/NaClO system under suitable conditions, the obtained water-insoluble oxidized products can be converted to characteristic nanomaterials by mechanical disintegration in water.

    • Akira Isogai
  • “Breath figure formation” during the casting process of polymer solutions under high atmospheric humidity provides honeycomb-patterned polymer films (honeycomb films) with regularly arranged micropores. The development of production technology for large-area honeycomb films is indispensable for their various applications. Manufacturing equipment consisting of three zones (for casting, humidification, and drying of polymer solutions) for successive formation of large-area honeycomb films was newly designed and constructed. By using this equipment, physicochemical experimental parameters, e.g., the surface temperature of polymer solutions, dew point of the humidification zone, humidification time, and interfacial tension between water and the polymer solution, were effectively changed to optimize the density and size of condensed water droplets. Large-area honeycomb films were formed by a roll-to-roll process. Herein, recent developments in biomedical applications of honeycomb films are described.

    • Hidekazu Yamazaki
    • Soichi Kohashi
    • Masatsugu Shimomura
  • Our recent progress on the phenylazomethine dendrimers to afford advanced functionalities due to the π-conjugated azomethine structure and electronic state are reviewed. The functions include luminous dendrimers by bismuth assembly, Y-shape recognition using porphyrin core, and atomicity-controlled template of metal salts on imine parts. The precisely controlled template ability developed synthesis of multimetallic subnanoparticles and superatoms that can mimic the properties of elemental atoms.

    • Tetsuya Kambe
    • Kimihisa Yamamoto
  • Block copolymers are used as nano-tools for delivering hydrophobic drugs. Their formulation requires robust characterization and clarification of the critical quality attributes correlating with the safety and efficacy. Static solution scattering from block copolymers is one such technique. This paper outlines the theoretical background and current models for analyzing this scattering and then presents an overview of our recent studies on block copolymers.

    • Isamu Akiba
    • Kazuo Sakurai
    Review Open Access
  • Recent developments in the one-step synthesis of structurally controlled hyperbranched polymers (HBPs) in terms of molecular weight, dispersity, number of branching points, branching density, and number of chain-end groups by radical polymerization are summarized. Copolymerization of conventional vinyl monomers and a vinyl telluride, which induces the branching structure, under organotellurium-mediated radical polymerization (TERP) affords HBPs with dendrimer and dendron structures. The same synthetic strategy under atom transfer radical polymerization is also discussed.

    • Shigeru Yamago
  • Polyhydroxyalkanoates (PHAs) are biobased and biodegradable materials. The artificial PHAs, such as lactate-based polymers, synthesized by engineered platforms expand the range of physical properties. The artificial polymers with superior properties are produced mainly from CO2-derived biomass using microbial platform with engineered enzymes. The oligomers can be secreted from cells and derivatized into high-molecular-weight polymers through assembling with other segments. The review summaries recent advances in the biosynthesis and biodegradation of artificial PHAs and oligomers.

    • Seiichi Taguchi
    • Ken’ichiro Matsumoto
  • To shift from a petroleum-dependent society to a sustainable society using eco-friendly materials, polysaccharides from natural products are important candidates as alternative materials. We have researched one of the cyanobacterial polysaccharides, “sacran,” which is extracted from Aphanothece sacrum. In this review, the unique characteristics, structures, and preparation of sacran LC gels are introduced. These matters are discussed especially from the perspectives of polymer science, colloidal science, gel science, etc. We hope that sacran will be used in a variety of fields, such as tissue engineering, pharmacodynamics, and biomedical materials, with possible contributions to the development of a sustainable material society.

    • Kosuke Okeyoshi
    • Maiko K. Okajima
    • Tatsuo Kaneko
  • To establish a sustainable material production system and preserve the Earth’s environment, “biomass plastics” that are made from renewable biomass instead of petroleum and “biodegradable plastics” that are completely degraded into carbon dioxide and water by enzymes secreted by microorganisms in the environment are desirable products. This miniature review describes a series of studies on microbial polyesters and polysaccharide ester derivatives, including the synthesis of novel polymers, development of new processing techniques for high-performance films and fibers, elucidation of the relationship between structure and properties using synchrotron radiation, and control of the rate of enzymatic degradation.

    • Tadahisa Iwata
    • Hongyi Gan
    • Yuya Fukata
  • Biodegradable plastics are gaining attention as one of the solutions to marine plastic wastes, which are increasing every year. Among them, polyhydroxyalkanoate (PHA) and polycaprolactone (PCL) are known to exhibit particularly good marine biodegradability. In this review, to understand their excellent marine biodegradability, the biosynthesis of PHA and cutin, a natural analog of PCL, and the biodegradation of PHA and PCL in the carbon cycle in marine ecosystems are described.

    • Miwa Suzuki
    • Yuya Tachibana
    • Ken-ichi Kasuya
    Review Open Access
  • This article reviews an evaluation-oriented exploration of photo energy conversion systems including organic photovoltaics, perovskite solar cells, photocatalysts, and photodetectors. A time-resolved spectroscopy using a gigahertz electromagnetic wave enables rapid screening of potential optoelectronics of organic/inorganic semiconductors and fast finding of their optimal film processing conditions. This approach is further empowered by machine learning that provides a high-throughput virtual screening in the large molecular space. The author discusses a perspective on this evaluation (from fundamental to application) and its effective combination with data science.

    • Akinori Saeki
    Review Open Access
  • The use of iron catalysts in CO2/epoxide chemistry has been less explored compared with zinc, cobalt, and chromium catalysts. This review highlights recent examples including iron complexes that deoxygenate epoxides in situ and geometry-dependent selectivity towards either polycarbonate or cyclic carbonate production. Reaction conditions (temperature, CO2 pressure, and amount of nucleophilic cocatalyst) and catalyst structure are all critical in accessing efficient catalysis for polycarbonate formation.

    • Kori A. Andrea
    • Francesca M. Kerton