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  • Fused expanded pyridinium cation (FEP) was introduced as a side chain of the polymer by click reaction. The obtained polymer offered membranes with good flexibility and showed excellent anion conductivity of 123.4 mS cm–1 at 80 °C under 80% relative humidity, although ion-exchange capacity of the polymer was quite low (0.77). Remarkable conductivity of the membranes is likely due to the weak interaction between FEP cation and OH, which increases the ion mobility and concentration of OH.

    • Yuki Motoishi
    • Naoki Tanaka
    • Tsuyohiko Fujigaya
    Original Article
  • 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
  • Intrinsically stretchable semiconducting polymer materials have been sought for meeting requirements in the development of wearable intelligent electronic devices. In this focus review, our recent progress in main-chain engineering for development of intrinsically stretchable n-type semiconducting materials is described. The topics include four strategies, namely, (i) a conjugation-break spacer approach, (ii) a block copolymer approach, (iii) an all-conjugated statistical terpolymer approach, and (iv) a sequence random copolymer approach, in which specially designed stress-relaxation units or sequences are incorporated along the main chains of naphthalene-diimide-based n-type semiconducting polymers.

    • Megumi Matsuda
    • Kei-ichiro Sato
    • Tomoya Higashihara
    Focus Review
  • The new strategy of two different AS-ODNs (targeting K-ras and YB-1) being delivered simultaneously to the same target cancer cell was investigated using the quantized complex made from AS-ODNs and short β-glucan (schizophyllan (SPG)). We used the quantized complex properties to prepare both end complexes with AS-ODNs on both ends. Both end complexes silenced two target genes and showed high inhibition of cancer cell growth. The results indicate that both end complexes can deliver two antisense sequences at the same time and show a synergistic effect.

    • Yuki Hata
    • Kazuki Sumiya
    • Kazuo Sakurai
  • Stretchable mechanoelectric generators (MEGs) using ‘π-electrets’ composed of π-conjugated polymers modified with bulky, yet flexible alkyl side chains were fabricated. Facile control of the elastic modulus by blending two miscible alkylated π-conjugated polymers enables the laminated films in a MEG to have high stretching of up to 300%. The fabricated MEGs showed good conformability when applied to a soft object that underwent deformation.

    • Akira Shinohara
    • Manabu Yoshida
    • Takashi Nakanishi
    Original Article 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
  • We performed cationic ring-opening polycondensation of a galactose-based cyclic sulfite monomer to give (1 → 2)-galactan. Treatment of the cyclic sulfite with 10-(+)-camphorsulfonic acid (CSA) in the presence of water initiated ring-opening polycondensation to give benzylated (1 → 2)-galactan. The MALDI-TOF mass spectrum of the obtained polymer showed a simple pattern with even intervals, indicating the formation of benzylated (1 → 2)-galactan with OH termini. When we used 4-penten-1-ol as the alcohol initiator for cationic polycondensation, we obtained a pentenoyl group-terminated polymer and/or cyclic oligosaccharides. The mechanism for the polycondensation reaction was determine through systematic investigations of the polymerization and DOSY spectral measurements of the polymer. The present method may be useful with graft polymerizations designed to give oligogalactan-containing glycosides in one pot.

    • Ryo Miyazaki
    • Misaki Suzuki
    • Yasuhito Koyama
    Original Article
  • Water-insoluble poly(methacrylic acid) (poly(MAAc)) sponges with nanolayered structures were fabricated via thermal cross-linking with poly(vinyl alcohol) (PVA). The cross-linked sponges contained up to 75 wt% poly(MAAc) when the molecular weight of PVA and the cross-linking time were adjusted appropriately. After immersion in a NaClO·5H2O aqueous solution, all poly(MAAc)/PVA_50 wt% sponges with different PVA molecular weights were completely dissolved. Multilayer films of poly(MAAc)/PVA with different physicochemical properties were also fabricated. Among potential applications, these sponges can be used as adsorption materials for low molecular weight compounds and heavy metal ions.

    • Daiki Kobayashi
    • Haruki Uchida
    • Yohei Kotsuchibashi
    Original Article
  • Transition metal-free aldol condensation was applied to synthesize n-type conjugated polyelectrolyte (CPE), PIIGBDV-N. The quaternary ammonium groups with Br- ions on the side chain enabled in situ n-doping during polymerization, which resulted in strong polaron absorption in the near infrared region and increased conductivity of the obtained CPE. PIIGBDV-N exhibited good electron transport capability and can be utilized as thickness-insensitive electron transporting layer in high-performance organic solar cell devices.

    • Haoran Tang
    • Yuejia Dou
    • Yong Cao
    Original Article
  • Fused π−conjugated molecules have been utilized as key components in organic semiconductors due to their high charge-transport characteristics. In this study, we designed and synthesized a novel fused π−conjugated molecule composed of electron-donating benzodithiophene and electron-accepting naphthobisthiadiazole units and investigated its photo/electrochemical properties and semiconducting characteristics. The fused donor-acceptor-donor (DAD) molecule showed typical p-type characteristics with a hole mobility of 1.1 × 10−3 cm2 V−1 s−1. We also achieved the synthesis of a D-A type copolymer containing the fused DAD structure as an electron donor unit.

    • Ryo Asakawa
    • Takuji Seo
    • Yutaka Ie
    Original Article
  • As the performance of organic semiconductors has increased so has their molecular structure. In this focused review, we introduce the concept of synergistic catalysis, which involves the use of two or more catalysts with orthogonal reactivity to enable reactions that are not possible with the use of a single catalyst, to synthesize π-conjugated polymers. Synergistic catalysis allows for controlled polymerizations, room-temperature reactions, and/or polymerizations with greater regioselectivity, opening the door to more time-, labor-, cost-, and energy-saving synthetic methods.

    • C. K. Luscombe
    • S. Phan
    • I. Sanskriti
    Focus Review Open Access
  • Ternary phase diagrams of the solvent/donor/acceptor system were studied to discuss the relationship between the photovoltaic properties of polymer solar cells and the phase-separated structures. The downshifted intersection points between the solvent drying pathway and binodal lines suggest the smaller domain sizes, and hence the higher exciton diffusion efficiency. The appropriate acceptor volume fraction close to the percolation threshold in mixed-phase shows high charge collection efficiency due to an effective charge transport and a suppressed bimolecular recombination.

    • Jihun Jeon
    • Kiyotaka Doi
    • Hideo Ohkita
    Original Article
  • By integrating the strongly electron-deficient building blocks cyano-substituted benzochalcogenadiazole and diketopyrrolopyrrole, two A-A polymers were constructed and exhibited decent solubilities, low-lying LUMOs, and ultra-narrow bandgaps, thus leading to a predominant n-type transporting characteristics. When n-type doped with N-DMBI-H, the A-A polymers delivered an n-type performance with a power factor of 9.22 μW m−1 K−2. The design strategy is highly informative for further developing n-type organic thermoelectric materials.

    • Junwei Wang
    • Kui Feng
    • Xugang Guo
    Original Article
  • A better understanding of the carrier formation process for semiconducting polymers, especially in thin films, is essential for designing and constructing highly-functionalized polymeric optoelectronic devices. We herein examined effects of the crystalline structure and thermal molecular motion on photo-carrier formation for melt-crystalized thin films of monodisperse poly(3-hexylthiophene) (P3HT) with various molecular weights (MWs), which were prepared from polydisperse sample by preparative chromatography.

    • Daisuke Kawaguchi
    • Ayano Higasayama
    • Keiji Tanaka
    Original Article
  • C–H/C–I direct arylation reactions for monomer synthesis and C–H/C–Br direct arylation polycondensation were investigated for the short-step synthesis of promising medium-bandgap polymers (PBDB-T) for OPV applications. Polycondensation and end-capping reactions using direct arylation have been established, enabling the synthesis of polymers without Br termini. The OPV performance of the synthesized polymer was lower than that of the benchmark polymer synthesized using the conventional method, despite having similar molecular weights. Possible factors for low OPV performance and future challenges include structural defects, impurities, and large molecular weight distribution.

    • Junpei Kuwabara
    • Kota Hiyaji
    • Takaki Kanbara
    Original Article
  • The 2D WAXD/SAXS data collected using a synchrotron X-ray microbeam technique revealed the details of the lamellar twisting phenomenon of high-density polyethylene spherulites. The molecular mechanics calculation, performed for large aggregation models of alkane chains having bulky head groups or folded polyethylene chains, has successfully reproduced the lamellar twisting pitch of a few μm, as extracted from the X–ray data analysis.

    • Hiroko Yamamoto
    • Taiyo Yoshioka
    • Kohji Tashiro
    Original Article
  • Reversible complexation mediated polymerization (RCMP) was demonstrated in the presence of an aqueous phase using various amine catalysts and monomers to investigate the effect of hydrophobicity of amine catalysts and monomers on the polymerization control of RCMP in aqueous heterogeneous systems. The essential criteria for polymerization control were (i) sufficient hydrophobicity of initiators and catalysts to enable partitioning into monomer phases, (ii) a suitable I2 concentration and temperature for improving polymerization control using long-alkyl chain amine catalysts, and (iii) sufficient monomer hydrophobicity to suppress water solubilization into monomer phase.

    • Yukiya Kitayama
    • Daiki Tokura
    • Atsushi Harada
    Original Article