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  • Blends of poly(lactic acid) (PLA) and thermoplastic starch (TPS) are promising biodegradable plastics, although their poor compatibility results in poor physical properties. In this study, oligo(lactic acid)-grafted starch (OLAgSt) was synthesized and added to PLA/TPS blends as a compatibilizer, and the physical properties of the obtained blends were evaluated. OLAgSt was synthesized by ring-opening polymerization of L-lactide using the hydroxy group of tapioca starch as an initiator. OLAgSt not only enhanced the dispersion of TPS within PLA, but also improved the biodegradability of the blend in a seawater environment.

    • Kazuki Shibasaki
    • Yu-I Hsu
    • Hiroshi Uyama
    Original Article
  • The gel-phase diagrams of temperature-responsive and biocompatible polymers with ethylene oxide (EO) side chains that differ in length were obtained. The gelation thresholds of the polymers depend not only on the monomer and crosslinker concentrations but also on the EO side chain lengths. Long EO side chains reduce the polymer overlap concentration. Furthermore, the EO side chains can engage in self-crosslinking, i.e., polymers can grow from the side chains depending on their length. These unique behaviors indicate that gelation occurs more readily with increasing the side chain length.

    • Takuma Kureha
    • Takuto Hirayama
    • Taichi Nishi
    Original Article
  • Induction of helical structures in peptides have been shown to increase their membrane permeability and facilitate cargo delivery applications. Our study has shown that substitution of an unnatural amino acid into a mitochondrial-targeting peptide induces a helical conformation that is maintained even after conjugation onto carbon nanotubes and confers increased membrane permeability. This led to an increase in DNA delivery efficiencies and gene expression into the mitochondria of intact plants when used as a DNA delivery system.

    • Simon Sau Yin Law
    • Mako Kuzumoto
    • Keiji Numata
    Original ArticleOpen Access
  • This study developed a novel method for the control of the cellulose crystal of cellulose I and II. The crystal transition from cellulose I to II was tracked when cellulose I, which is soaked in a low-concentration NaOH aqueous solution, was quenched using liquid nitrogen. The crystal transition progressed from the surface to the center of the sample. This quench treatment has the potential to fabricate new cellulose materials with a cellulose I core and a cellulose II surface.

    • Yuki Kugo
    • Takuya Isono
    • Kenji Tajima
  • This study presented the workflow of machine learning-guided optimization of Pd-immobilized porous polymer catalysts. Two independent variables (DVB and 1-decanol content) were involved in polymerization to maximize TOF as target variable in Suzuki–Miyaura coupling reaction. Bayesian optimization was applied for predictive modeling, and the optimized conditions were experimentally validated in subsequent iterations. By applying this workflow, the catalytic activity of immobilized polymer porous catalysts was successfully optimized using machine learning.

    • Xincheng Zhou
    • Hikaru Matsumoto
    • Yoshiko Miura
    Original Article
  • The crystalline surface using two photochromic diarylethenes was prepared to mimic a termite wing showing dual wettability. The surface is useful to correct small water droplets in the air. However, the crystalline system was not applicable for the use because crystalline structures on the surface melt under daylight. We copied the rough structure of crystalline film to a stable polycycloolefin polymer (Zeonex 480) surface. The copied surface showed the dual wettability as same as that of the crystalline surface.

    • Yuki Hashimoto
    • Amane Hase
    • Kingo Uchida
    Original Article
  • We have investigated the self-assembly kinetics of silica nanoparticles (SNPs) into the polymer-like structure by time-resolved small-angle X-ray scattering (SAXS). The analysis of the SAXS data with a kinetic model revealed that the SNPs undergo self-assembly in a process akin to the step-growth polymerization of bifunctional monomers. This study offers a facile strategy to construct polymer-like structures from isotropic spherical nanoparticles.

    • Tatsuki Oishi
    • Ayae Sugawara-Narutaki
    • Rintaro Takahashi
    Rapid CommunicationOpen Access
  • The relationships between the macroscopic mechanical properties and lamellar structures of polyamide 11 obtained from different heat treatments were investigated. From the tensile tests, the maximum stress and strain at necking increase with the heat treatment temperature. WAXS measurements indicated that different crystalline phases formed depending on the heat treatment conditions. SAXS revealed that the lamellar thickness and long period increased with the heat treatment temperature. Based on these results, we elucidated that the macroscopic mechanical properties correlate with the lamellar thickness and long period.

    • Toyoshi Yoshida
    • Mei Touji
    • Yoshihisa Kaneko
    Original Article
  • We explored the feasibility of Tetra-PEG gel, a controllable hydrogel, as a new biomaterial to develop a coating agent for post-ESD ulcers. We examined the optimal conditions for hydrogel application and developed a specialized catheter, then investigated its properties. Ultimately, we successfully used the optimized hydrogel and device to cover post-ESD ulcers in the porcine stomach. Further optimization of the hydrogel and ongoing research through animal experiments are expected to deepen our understanding of the material’s effects on ulcer healing and contribute to its clinical applications.

    • Rina Cho
    • Hiroyuki Kamata
    • Mitsuhiro Fujishiro
    Original ArticleOpen Access
  • The effects of an organic monoglyceride (OMG) plasticizer on the crystallization of the PLLA/PDLA (50/50) blend were investigated by examining the isothermal crystallization of the blend with different contents of OMG (1–5 wt%) using POM, DSC, and time-resolved WAXD. It was found that the increase of the OMG content promoted the exclusive formation of stereocomplex crystallites and enhanced its crystallinity while suppressing the formation of homocrystals.

    • Neimatallah Hosni Mohammed Mahmoud
    • Hideaki Takagi
    • Shinichi Sakurai
    Original Article
  • The thiol-Michael polyaddition of three dialkynyl monomers with several dithiols proceeded using triethylamine as the catalyst to give unsaturated poly(ester-thioether)s with the expected structures (Mn, 2.4 × 103 to 22.6 × 103; molecular dispersity index [Mw/Mn], 1.26–2.00). All of the poly(ester-thioester)s had single glass-transition temperature values between −27 and 49 °C. While the rigid main chains improved the glass transition temperature, all of the poly(ester-thioester)s showed apparent enzymatic hydrolysis by lipase but low biodegradability in biodegradation tests using activated sludge.

    • Katsuhisa Yano
    • Akinori Takasu
    • Hiroshi Eguchi
    Original ArticleOpen Access
  • The Suzuki–Miyaura coupling reaction of BrC6H4-SiRR’-C6H4Br 1 with phenylboronic acid 3 in the presence of tBu3PPd precatalyst 4 and CsF/18-crown-6 produced a phenyl-disubstituted product, indicating that the Pd catalyst underwent catalyst transfer on the silylene group. The polycondensation of 1 and phenylenediboronic acid 2 yielded cyclic polymers even when excess 1 was used. The obtained cyclic polymers containing the silylene group showed stronger fluorescence in solution than did the methylene counterpart.

    • Natsumi Harada
    • Rina Yachida
    • Tsutomu Yokozawa
  • Three cyclic oxoester-thioester hybrid monomers were studied for anionic and cationic ring-opening polymerizations. Anionic polymerizations using thiol with 2,6-lutidine were successful for the chemoselective cleavage of the thioester with the thiol propagating end, exhibiting the living character to some extent. The polymerization in 2,6-lutidine without an initiator produced macrocyclic polymers. The cationic polymerizations occurred with the aid of CF3SO3H and benzyl alcohol but involved side reactions with low chemoselective ring cleavage. The thioester unit caused the polymers to exhibit a lower Tg with greater thermal and photo degradability.

    • Mao Hirata
    • Tomoki Yoshimatsu
    • Masato Suzuki
    Original ArticleOpen Access
  • Doping lanthanides into lamellar crystals of diacetylene derivatives with terminal carboxylic acids reorganized the lamellar structure and dramatically changed the crystal morphology. Detailed investigation of the crystal growth process revealed that the complexes of lanthanide and diacetylene derivatives, which are slightly formed in the solution phase during lanthanide doping, may act as a pseudonuclear agent and change the morphology of the lamellar crystals. Furthermore, the morphology changes of the lamellar crystal films significantly altered surface properties such as film appearance and water repellency.

    • Michinari Kohri
    • Sojiro Isomura
    • Keiki Kishikawa
    Original ArticleOpen Access
  • Simple control of the thermoresponsive properties of polymers in water over a broad range is achieved by using a designed urethane-containing acrylamide monomer in combination with a hydroxy-containing precursor monomer, which forms a statistical sequence due to its similar backbone. The copolymers exhibited a lower critical solution temperature-type responsive behavior in water, and the effects of structural factors such as composition, molecular weight, end groups and side-chain structure in urethane monomers were systematically evaluated.

    • Shohei Ida
    • Ryu Hashiguchi
    • Shokyoku Kanaoka
    Original Article
  • Natural rubber exhibits the strain-induced crystallization (SIC). By using WAXD, the orientation of NR crystal formed by SIC under planar elongation was revisited. We found that the orientational state of the crystal lattice possesses a continuous margin of the orientation angle between 6.4 and 19.6° for the ac plane with respect to the surface of the specimen sheet in the real NR specimen. This orientational state could be accomplished as a result of balancing the preferential parallel orientation of (120) planes (the slip planes) and C = C planes with respect to the surface of the specimen sheet.

    • Ruito Tanaka
    • Tomohiro Yasui
    • Shinichi Sakurai
    Original Article
  • We synthesized a new benzobisthiazole (BBTz) containing building unit in which two alkoxythiophenes were attached to the BBTz moiety so as to induce oxygen–sulfur noncovalent intramolecular interactions and thereby interlock the linkage. As a result, the π-conjugated polymer incorporating the new building unit, PDBTz2, had a more coplanar and rigid backbone than the alkyl counterpart, PDBTz1. Interestingly, the backbone orientation was completely altered from the edge-on orientation (PDBTz1) to the face-on orientation (PDBTz2), which is preferable for organic photovoltaics. Accordingly, PDBTz2 showed a much higher photovoltaic performance than PDBTz1.

    • Shuhei Doi
    • Tsubasa Mikie
    • Itaru Osaka
    Original ArticleOpen Access
  • The surface properties of the star polymer coating were evaluated with their resistance to protein adsorption and surface zeta (ζ)-potential to clarify the mechanism for inhibition of cell adhesion. The surface of the star polymer coating with a high density of poly(2-hydroxyethyl methacrylate) formed an electrically neutral diffuse brush structure in water and showed high resistance to protein adsorption. Considering the data obtained in the study, the surface ζ-potential and antibiofouling properties were correlated by controlling the molecular architecture of the coating material.

    • Masayasu Totani
    • Hiroharu Ajiro
    • Tsuyoshi Ando
  • Developing fluorescence anion sensors is important because anions play a significant role in various biological phenomena. Herein, we evaluated the anion binding properties of a polyhedral oligomeric silsesquioxane (POSS) derivative with eight urea groups and a 3D structure. The results revealed that the POSS derivative with urea groups can bind to sulfate ions and exhibits a greater binding ability than that of the model compound because multiple urea groups exhibit cooperative effects. Through the introduction of naphthyl urea groups, the POSS derivative can be used as a fluorescence sensor for quantifying sulfate ions.

    • Hayato Narikiyo
    • Masayuki Gon
    • Yoshiki Chujo
    Original Article