Browse Articles

Filter By:

  • Performance limiting factors in three end-group-brominated ITIC (β, γ, δ):PM6 bulk-heterojunction (BHJ) organic solar cells (OSCs) were investigated. The charge carrier dynamics (mobility and its relaxation) in these OSCs were evaluated by simultaneous time-of-flight (TOF)-time-resolved microwave conductivity (TRMC) measurement and photoinduced charge extraction by linearly increasing voltage (photo-CELIV) technique. The charge separation and recombination were found to be stronger power conversion efficiency-governing factors than mobilities and their balance, as suggested by regression analyses.

    • Shaoxian Li
    • Ryosuke Nishikubo
    • Akinori Saeki
    Original Article
  • We demonstrate the synthesis of head-to-tail (HT) regioregular poly(3-hexylthiophene) (P3HT) with controlled molecular weight via direct arylation polymerization (DArP). The key to control is using 2-phenylthiazole (2), which has a C–H bond with high reactivity for direct arylation, as the end-capping reagent. The DArP of 2-bromo-3-hexylthiophene (1) in the presence of 2 ([1]0/[2]0 = 10–80), Herrmann-Beller catalyst, and P(o-Me2NC6H4)3 afforded HT-regioregular P3HT (HT = 99%) capped with a 2-phenylthiazole-5-yl group. The number-average molecular weight (Mn) of P3HT agreed well with the value calculated by assuming the formation of one polymer chain per molecule of 2 (polydispersity index: Ð = 1.8–2.1).

    • Masayuki Wakioka
    • Kai Xu
    • Fumiyuki Ozawa
    Original Article
  • Vinylene-bridged 5-alkoxy-6-fluorobenzo[c][1,2,5]thiadiazole (FOBTzE) as a novel acceptor unit and its copolymer PFOE4T were designed and synthesized. The incorporation of an electron-donating alkoxy group instead of a fluorine atom prevented strong aggregation tendency and changed the molecular orientation of the polymers from edge-on to bimodal orientation, which was expected to provide uniform thin-film with PC61BM and promoted carrier transport. However, since PFOE4T has still strong aggregation ability and low solubility, the PFOE4T/PC61BM blended film formed a large phase separation, resulting in a power conversion efficiency of only 4.52%.

    • Hiroki Mori
    • Yuya Asanuma
    • Yasushi Nishihara
    Original Article
  • The folding behavior of a 2-dimethylaminoethyl methacrylate oligomer with alternately protonated side chains surrounded by water molecules was evaluated using molecular dynamics simulations in the temperature range of 280–360 K. Radial distribution functions (RDFs) around the geometric center of the oligomer were evaluated; they indicated that protonated amine groups surrounded the aggregating deprotonated amine groups in the globule state. The calculation of RDFs around the geometric center is a highly reliable strategy to evaluate the folding behavior of stimuli-responsive polymer gels during the coil-to-globule transition.

    • Ryo Nagumo
    • Kazuma Nishikawa
    • Shuichi Iwata
    Original Article
  • Optically active through-space conjugated polymers were prepared from planar chiral pseudo-meta-disubstituted [2.2]paracyclophane. The corresponding optically active pseudo-meta-linked dimers were also prepared, and their optical and chiroptical properties were compared with those of the pseudo-para- and pseudo-ortho-linked dimers. Optically active pseudo-meta-linked dimers and polymers emitted intense circularly polarized luminescence with good anisotropy factors on the order of 10–3. The electrical photoconductivities of the racemic pseudo-meta- and pseudo-para-linked polymers were also evaluated. A number of properties were explained by using time-dependent density functional theory calculations.

    • Hazuki Maeda
    • Ryo Inoue
    • Yasuhiro Morisaki
    Original Article
  • The effects of incorporating poly(d,l-lactide) (PDLLA) and solvent on the stereocomplex (SC) crystallization and homocrystallization of poly(l-lactide) (PLLA) and poly(d-lactide) (PDLA) chains were explored using linear one-armed PLLA (1-L)/PDLA (1-D) and linear one-armed PDLLA (1-DL) as an unconstrained system and using four-armed PLLA-b-PDLA (4-L-D) and linear one-armed 1-DL as a constrained system. The dilution effects of PDLLA and solvent enhanced SC crystallization and suppressed homocrystallization, with the exception of the constrained 4-L-D/1-DL blends in the presence of both PDLLA and solvent.

    • Hideto Tsuji
    • Sena Nogata
    • Yuki Arakawa
    Original Article
  • In situ infrared spectroscopy and two-dimensional (2D) correlation analysis was applied to research the chemical changes and curing reaction mechanism of epoxy resin and amine curing agents. The curing reaction mechanism can be deeply understood from the results. Due to the nucleophilic addition reaction of amino and epoxy groups, the nitrogen atoms easily combine with the carbon atoms, which forms new C-N groups. Then, the C-O bonds break; finally, as the N-H bonds in primary amines break, the hydrogen atoms combine with the oxygen atoms to form new hydroxyl groups.

    • Zhipeng He
    • Wei Lv
    • Qinwei Yin
    Original Article
  • We investigated the hydration behaviors of PEG and PEGylated dendrimer using X-ray diffraction, infrared spectroscopy, and differential scanning calorimetry analysis in the range of −80 °C to 80 °C. At 20% water content, ice crystals were formed and melted during the heating. At 70% water content, however, PEG crystals were formed and melted. In the mixture of the PEGylated dendrimer with 20% water content, ice formation was suppressed. Comparative analyses are important for the evaluation of such eutectic mixtures of PEG compounds and water.

    • Chie Kojima
    • Yasuhito Suzuki
    • Akikazu Matsumoto
    Original Article
  • Conducting polymer support with atomically dispersed metal centers for oxygen reduction and evolution reaction catalysis is a promising strategy to enhance the cyclability of Li–O2 battery. We present a novel, reliable and highly efficient noble metal free polymer catalyst for Li air battery application. Novel cathode catalyst found to be very efficient for nearly 160 cycles with limiting the capacity to 500 mAh/g with relatively lower overpotential.

    • Rajashekar Badam
    • Mayu Shibuya
    • Noriyoshi Matsumi
    Original Article
  • We demonstrated biomolecular motors driven swarming of microtubules and their dissociation under UV and visible light irradiation, respectively. A photoresponsive molecule, para tert-butyl-substituted azobenzene was incorporated to the backbone of single strand DNA, which functions as a photoswitch to control the swarming of microtubules in a reversible manner. This work is expected to expand the potential applications of biomolecular motors in developing photoregulated molecular machines.

    • Satsuki Ishii
    • Mousumi Akter
    • Akira Kakugo
    Rapid Communication
  • This review focuses on the controlled radical polymerization of vinyl ether (VE) and the related self-assemblies. VE was long believed to be among the monomers that could not be radically homopolymerized. Under such circumstances, some groundbreaking polymerizations of VE have been discovered. Advances in research have made it possible to perform controlled radical polymerization with VE due to hydrogen bonds and/or cation-π interactions between VE monomers and the propagating radical. By using the resulting poly(VE)s, various functional polymers and nano-objects via polymerization-induced self-assembly can be obtained.

    • Shinji Sugihara
    Focus Review
  • P3HT embedded with N- and NS-GQDs exhibit quite similar crystallinities independently of the solvent used, as suggested by our molecular dynamics calculations for the amorphous and crystalline regions. The vibrational, optical and impedance spectroscopy features suggest charge carrier formation in both the amorphous and crystalline regions but only for the P3HT:NS-GQDs system in relation to the donor:acceptor interactions evidenced by our DFT calculations.

    • Dominique Mombrú
    • Mariano Romero
    • Álvaro W. Mombrú
    Original Article
  • This focus review discussed our recent developments of unnatural glycopolymers based on polyoxazoline, protein–polymer conjugates, and protein stabilization. To develop new glycopolymers, a bicyclic monomer composed of glucosamine and 2-methyl-2-oxazoline (MeOx) was designed. This cationic ring-opening polymerization proceeded not by the mechanism for MeOx but by a new polymerization mechanism. This oligosaccharide has promise to be applied to a new glycomaterial owing to the polymer design. Additionally, protein conjugation and encapsulation by amphiphilic/fluorous chain-folding nanoparticles were investigated. Fluorous nature in random copolymers was useful for the protein conjugation and stabilization.

    • Yuta Koda
    Focus Review
  • The lithium halides; LiBr, LiCl, and LiI were well dispersed in the PMMA matrix. The pinning effects of the PMMA chains due to the addition of the salts were enhanced in the viscoelastic spectra with increasing as the anion sizes. Moreover, it was suggested from the Griffith Theory, the stress concentration around the salts in the PMMA matrix acts as the crack initiation.

    • Asae Ito
    • Arisa Shin
    • Koh-hei Nitta
    Original Article
  • The polymer chain morphologies of poly(4-iodostyrene) (P4IS) adsorbed on gold nanoparticles (GNPs) inside a polystyrene matrix were visualized using annular dark-field scanning transmission electron microscopy. The P4IS polymer chains adsorbed on GNPs exhibited a unique morphology wherein 1–2 molecular layers of P4IS surrounded a GNP, and the rest of the P4IS was aggregated at the side of the GNP. Enthalpy gain for the surrounding layer via adsorption and entropy gain for the remaining polymer chains via aggregation was considered the reason why the morphology was preferred.

    • Tomohiro Miyata
    • Yoshiaki Kawagoe
    • Hiroshi Jinnai
    Original Article
  • The drug release behaviors of gelatin hydrogels prepared with polymers in terms of their rheological properties were evaluated. In the oscillatory strain sweep, gelatin/HPMCP hydrogels showed a higher crossover strain (Tan δ = 1) than gelatin and gelatin/Eudragit® hydrogels. Thus, gelatin/HPMCP hydrogels had the property of elastic hydrocolloids and tended to keep the platform compared with other sample hydrogels. As a result, the drug release from gelatin/HPMCP hydrogels was delayed compared with other sample hydrogels at pH 1.2.

    • Satoshi Nogami
    • Kazunori Kadota
    • Yuichi Tozuka
    Original Article
  • The first ultrasoft aqueous lithium-ion batteries with coaxial fiber structures were fabricated with an all-hydrogel design. The all-hydrogel fiber aqueous Li-ion battery exhibited a high specific discharge capacity of 84.8 mAh·g−1 and superior cycling behavior and rate capacity performance. A low Young’s modulus (e.g., 445 kPa) for the battery was achieved by making it entirely from hydrogels, which ensured mechanical compatibility with biological tissues.

    • Jiacheng Wang
    • Tingting Ye
    • Ye Zhang
    Rapid Communication
  • Viscoelastic properties of comb-shaped ring (RC) polystyrenes with different branch chain lengths were investigated. Even for the RC sample with short branches, a plateau of the dynamic modulus G*(ω) was observed, suggesting the intermolecular branch chain entanglement occurred. In the region between the plateau and terminal regions, G*(ω) was observed with a weaker angular frequency dependence than the terminal relaxation. The G*(ω) data were analyzed with two models: the comb-Rouse model, in which the structures of RC molecules are taken into account by graph theory, and the Milner-McLeish model for entangled star-shaped polymers.

    • Yuya Doi
    • Jinya Kitamura
    • Yushu Matsushita
    Original Article
  • Among stimuli-responsive polymers, thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm) is the most widely investigated. PNIPAAm-based polymers can undergo appropriate changes in response to their external environment. In this focus review, recent advancements in the applications of stimuli-responsive polymers based on PNIPAAm in biomedical fields are summarized, with an emphasis on our own research. In particular, a summary of the design of polymers for application in the separation and purification of (bio)pharmaceutical products and controlled cellular uptake is provided.

    • Yuki Hiruta
    Focus Review