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  • Fabrication and characterization of elastomeric semiconductive thiophene polymers by peroxide crosslinking
    Polym. J. (IF 2.17) Pub Date : 2018-10-17
    Jian Shen, Iori Sugimoto, Takuya Matsumoto, Shohei Horike, Yasuko Koshiba, Kenji Ishida, Atsunori Mori, Takashi Nishino

    In this study, semiconductive elastomers composed of homopolythiophene with disiloxane moieties were developed. The crosslinked molecular structure in the polythiophene elastomers was introduced by dicumyl peroxide, one of the typical peroxide crosslinking reagents. The elastomers were produced through a hot-pressing process above the melting point of the polythiophene. Stress–strain curves that included tensile tests and cycle loading–unloading tests defined the crosslinked polythiophenes as elastomers. Their electrical conductivities were evaluated by two-point measurements under nondeformation and uniaxial deformation states. The results indicated that the concentration of crosslinking reagents greatly influenced the mechanical and electrical properties of crosslinking polymers. With the addition of the crosslinking reagent in concentrations from 2.5 phr to 10.0 phr, elongation at break decreased largely from 95% to 51%, while excellent elastic recoveries were observed. In the electrical resistivity measurements, all the crosslinking polymers possessed high stability of electrical properties against elongation.

    更新日期:2018-10-17
  • Development of highly functional membranes through structural control of crystalline/amorphous phases
    Polym. J. (IF 2.17) Pub Date : 2018-10-12
    Hiroki Uehara

    AbstractMolecular entanglements have been thought to restrict a desirable chain orientation during drawing. Therefore, a reduction in chain entanglements has been a focus for manufacturing high-performance fibers and membranes. In contrast, our melt-drawing technique utilizes molecular entanglements as a strain transmitter, achieving a nanoperiodic arrangement in which the crystalline and amorphous phases are interconnected. This periodic structure is similar to microphase separation in block copolymers, in which linked points are located at the boundaries between chemically different phases. The results show highly functional membranes can be successfully prepared from highly entangled homopolymer, as well as block copolymer, using solvent-free procedures.

    更新日期:2018-10-12
  • Transition of liquid crystal anchoring at the microdomain interface observed for main-chain nematic polyester segments of block copolymers
    Polym. J. (IF 2.17) Pub Date : 2018-10-11
    Maito Koga, Takumi Wakabayashi, Sungmin Kang, Masatoshi Tokita

    The microdomain structures and liquid crystal (LC) orientations of ABA triblock copolymers comprising poly(styrene) (PS) A blocks and a main-chain LC polyester B block were examined via small-angle X-ray scattering and electron microscopy in the form of fibrous samples. The LC polyester blocks were segregated from the PS blocks to form a nematic LC in the lamellar microdomains of the copolymers, with the PS volume fraction (φ) ranging from 13 to 38%. As φ decreased, the nematic director was always positioned along the fiber axis, but the microdomain lamellae changed their direction from parallel to perpendicular with respect to the fiber axis and began to adopt a zigzag configuration. These lamellar orientations were attributed to the main-chain nematic LC segments lying along the microdomain interface but extending perpendicularly to the interface as the occupying interface area was reduced. The lamellar microdomains parallel to the nematic director increased the LC and PS lamellar thicknesses reversibly by 48 and 16%, respectively, at the same time as the isotropization of the nematic LC. Such changes in lamellar thickness suggest that both the PS and LC segments were elongated along the direction of the LC orientation.

    更新日期:2018-10-11
  • Segregation of an amine component in a model epoxy resin at a copper interface
    Polym. J. (IF 2.17) Pub Date : 2018-10-10
    Mika Aoki, Atsuomi Shundo, Kenji Okamoto, Tatsuya Ganbe, Keiji Tanaka

    Segregation of an amine component in a model epoxy resin at a copper interfaceSegregation of an amine component in a model epoxy resin at a copper interface, Published online: 10 October 2018; doi:10.1038/s41428-018-0129-4Epoxy resins, which are obtained by the curing reaction of epoxy- and amine-compounds mixture, have been often utilized in contact with metals. We herein report on the chemical composition of the epoxy resin in close proximity to the copper interface on the basis of a non-destructive method. The concentration of the amine component in the interfacial region was 2-fold higher than that in the bulk, and the interfacial enrichment extended over at least 10 nm.

    更新日期:2018-10-10
  • Stimuli-responsive supramolecular systems guided by chemical reactions
    Polym. J. (IF 2.17) Pub Date : 2018-10-05
    Masato Ikeda

    This focus review describes the development of stimuli-responsive supramolecular systems, emphasizing molecular design approach used to construct constituent molecular hybrids comprising chemically reactive small molecules and potentially functional biomolecules or bio-related molecules. The construction of stimuli-responsive supramolecular hydrogels and G-quadruplex-forming nucleic acids, despite the lack of substantial similarity at the supramolecular systems level, highlights the versatile applicability of the molecular design approach for exploring a variety of supramolecular (bio)materials endowed with tailor-made stimuli responsiveness.

    更新日期:2018-10-05
  • Synthesis of carboxylated derivatives of poly(isobutylene-co-isoprene) by azide–alkyne “click” chemistry
    Polym. J. (IF 2.17) Pub Date : 2018-09-28
    Vishnu D. Deepak, Ilias Mahmud, Mario Gauthier

    The synthesis of carboxylated derivatives of poly(isobutylene-co-isoprene) (isobutylene–isoprene rubber, IIR) with substitution levels ranging from 1 to 4 mol% and different spacer lengths was accomplished through azide–alkyne Huisgen cycloaddition. Azido-functionalized IIR was first prepared by reacting brominated IIR with sodium azide to full conversion in a 90:10 tetrahydrofuran/N,N-dimethylacetamide mixture. The click reaction of azido-functionalized IIR with acetylenic acids, which was carried out using the copper(I) bromide/N,N,N′,N″,N″-pentamethyldiethylenetriamine catalyst system in tetrahydrofuran, yielded carboxylated IIRs. The products were characterized by 1H NMR and FT-IR spectroscopy, and their molecular weight was determined by size exclusion chromatography analysis. The conversion to carboxylated groups reached up to 100% as determined by NMR spectroscopy but was highly dependent on the type of solvent and the amounts of catalysts and reactants used in the procedures.

    更新日期:2018-09-28
  • Relationship between twisting phenomenon and structural discontinuity of stacked lamellae in the spherulite of poly(ethylene adipate) as studied by the synchrotron X-ray microbeam technique
    Polym. J. (IF 2.17) Pub Date : 2018-09-27
    Kohji Tashiro, Taiyo Yoshioka, Hiroko Yamamoto, Hai Wang, Eamor M. Woo, Kenichi Funaki, Hiroki Murase

    Wide-angle and small-angle X-ray scattering measurements were performed simultaneously using an X-ray beam 1 μm in size to detect the inner structure of a spherulite of poly(ethylene adipate) [PEA, –(O(CH2)2OCO(CH2)4CO–)n–]. The lamellae were found to twist periodically by 180° in the area between the neighboring bright rings observed in the polarized optical microscope image of the spherulite. However, as known from the discontinuity between the repeated lamellar zones discovered by Woo et al. (Macromolecules, 45:1375–1383, 2012), the twisted lamellae must not be assumed to be continuously twisted long plates spreading out over the spherulite. Rather, these lamellae should be considered to have limited areas of ~7 μm in length along the radial direction and with disconnected end zones. The present X-ray scattering data revealed the structural relation between the repeated arrays of the disconnected lamellar blocks and the 180° twisting phenomenon, which occurs only in the finite and disconnected flat-on lamellar zones.

    更新日期:2018-09-27
  • Volume shrinkage of polypeptide hybrid xerogels induced by a helix-sense inversion
    Polym. J. (IF 2.17) Pub Date : 2018-09-26
    Yosuke Mizuno, Hidemine Furuya

    Poly(l-aspartic acid β-ester) molecules (PAsp) are known for their unique temperature-dependent helix-sense inversion from right- to left-handed helices. This secondary structure transition is expected to switch their mechanical properties, which would allow the development of a stimuli-responsive, solid-state systems of biomaterials. In this work, PAsp hybrid xerogels (PAsp-xgs), which are polymethylmethacrylate xerogels crosslinked by PAsp, were synthesized, and the effects of the PAsp helix-sense inversion on their properties were investigated. PAsp-xg was found to irreversibly shrink to a volume ratio of 0.7 when heated to ~393 K. Notably, the PAsp moieties in the xerogels exhibited a helix-sense inversion at a similar temperature to that of the helix-sense inversion in the homopolymer. These results suggest that the helix-sense inversion induced the volume shrinkage of the PAsp-xgs. All in all, the PAsp-xg synthesized herein is expected to be a new, low environmental load material for stimulus-responsive systems.

    更新日期:2018-09-26
  • DBU-catalyzed CO2 fixation in polypropargylamines under solvent-free conditions
    Polym. J. (IF 2.17) Pub Date : 2018-09-21
    Nam-Kyun Kim, Hiromitsu Sogawa, Mulyadi D. Felicia, Toshikazu Takata

    DBU-catalyzed CO2 fixation in polypropargylamines under solvent-free conditionsDBU-catalyzed CO<sub>2</sub> fixation in polypropargylamines under solvent-free conditions, Published online: 21 September 2018; doi:10.1038/s41428-018-0125-8Solvent-free base-catalyzed CO2 fixation into polymers having 2-pyridyl group-substituted propargylamine moieties in the main and side chains was achieved under atmospheric CO2 condition. The reactivity of the polymer films was improved by the introduction of pendant tertiary amine moiety.

    更新日期:2018-09-21
  • Designer supramolecular polymers with specific molecular recognitions
    Polym. J. (IF 2.17) Pub Date : 2018-09-21
    Takeharu Haino

    Supramolecular polymers are members of an emergent class of polymer materials that exhibit designability and flexibility. This article describes how supramolecular polymers can be synthesized by taking advantage of our host–guest structures based on a calix[5]arene, a bisporphyrin, and a self-assembled capsule. Linear and two-dimensional fullerene nanostructures can be fabricated using the designed monomer structures. The porphyrin donor–acceptor interaction directs the supramolecular polymerization, resulting in linear porphyrin polymers that behave similarly to a conventional polymer chain in solution, even though their structures are dynamic and time-averaged. The fragile supramolecular polymer chains are cross-linked to fabricate a robust self-standing film. The sequence reorganization of the supramolecular homopolymer is established by competitive ditopic guest complexation. The sequence-controlled terpolymer is fabricated via self-sorting behavior. The postmodifications of the supramolecular polymer chains, as well as the polymer chains themselves, are achieved by grafting and non-covalent cross-linking to regulate the macroscopic properties and structures of the polymer main chains. These uniquely organized polymers are fabricated on a nanoscale.

    更新日期:2018-09-21
  • Ethylene polymerization and ethylene/1-octene copolymerization with a titanium complex supported by a bis(indolyl) ligand
    Polym. J. (IF 2.17) Pub Date : 2018-09-19
    Shun Ohta, Yuki Kasai, Tomoyuki Toda, Kei Nishii, Masaaki Okazaki

    AbstractThe synthesis of bis(diethylamido){di(3-methylindol-2-yl)phenylmethane}titanium (1) was achieved in high yield (85%) by the treatment of 2,2′-di(3-methylindolyl)phenylmethane with Ti(NEt2)4 in toluene at reflux for 18 h. The ethylene polymerization activity of the 1/modified methylaluminoxane (MMAO) catalyst system was low (16.3 kg of polyethylene (PE)/mol of Ti•h), but pretreatment of 1 with ClSiMe3 followed by activation with MMAO improved the activity up to 154 kg of PE/mol of Ti•h. An NMR-scale reaction of 1 with ClSiMe3 in C6D6 at 80 °C for 22 h indicated the generation of an amido chlorido complex together with the formation of Et2N–SiMe3. Partial chlorination would facilitate methylation by MMAO. The polyethylenes obtained in this study are all monomodal by size exclusion chromatography and have linear structures by NMR spectroscopy. The catalyst system was also found to be active for ethylene/1-octene copolymerization (90 kg of copolymer/mol of Ti•h).

    更新日期:2018-09-19
  • Molecular dynamics study of the molecular mobilities and side-chain terminal affinities of 2-methoxyethyl acrylate and 2-hydroxyethyl methacrylate
    Polym. J. (IF 2.17) Pub Date : 2018-09-10
    Ryo Nagumo, Atsushi Shimizu, Shuichi Iwata, Hideki Mori

    Molecular dynamics study of the molecular mobilities and side-chain terminal affinities of 2-methoxyethyl acrylate and 2-hydroxyethyl methacrylateMolecular dynamics study of the molecular mobilities and side-chain terminal affinities of 2-methoxyethyl acrylate and 2-hydroxyethyl methacrylate, Published online: 10 September 2018; doi:10.1038/s41428-018-0121-zIrrespective of the degree of polymerization, the molecular mobilities of the 2-hydroxyethyl methacrylate (HEMA) moieties are smaller than those of the 2-methoxyethyl acrylate (MEA) moieties. Preventing the polar functional groups of the foulants and materials from forming a hydrogen-bonding network is important to enhance the mobilities of the molecular chains of non-ionic polymeric materials. We speculate that enhancing the mobilities of the molecular chains is key to improving blood compatibility.

    更新日期:2018-09-10
  • Study of active self-assembly using biomolecular motors
    Polym. J. (IF 2.17) Pub Date : 2018-09-07
    Arif Md. Rashedul Kabir, Akira Kakugo

    Self-propelled biomolecular motor systems, such as microtubule-kinesin or microtubule-dynein, are intricate natural machines with the ability to convert chemical energy into mechanical work with high efficiency. In recent years, the biomolecular motor systems have emerged as promising candidates for studying active self-assembly based on the in vitro gliding assay of the motor systems. Several strategies have been developed to demonstrate the active self-assembly of biomolecular motors, which provided a wealth of organized and complex structures. Here we review the latest progress in the active self-assembly of microtubule-kinesin and microtubule-dynein with an emphasis on the emergence of various structures and necessary design parameters for controlling their polymorphism.

    更新日期:2018-09-09
  • Novel conducting polymeric nanocomposites embedded with nanoclay: synthesis, photoluminescence, and corrosion protection performance
    Polym. J. (IF 2.17) Pub Date : 2018-09-07
    Kamal I. Aly, Osama Younis, Mahmoud H. Mahross, Osamu Tsutsumi, Mohamed Gamal Mohamed, Marwa M. Sayed

    In this work, new nanoclay composites were prepared through in situ polymerization for reported conducting polyarylidenes based on cyclopentanone and cyclohexanone moieties in the main chain. Additionally, a novel conducting polymer (CP), based on cycloheptanone, was synthesized along with its nanoclays. The studied materials were characterized via Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, scanning electron microscopy (SEM), and transmission electron microscopy (TEM). The main objective was to study the effect of nanoclay modification and ring size on CP solubility, thermal behavior, optical properties, and corrosion inhibition effects. The obtained results showed enhanced solubility and thermal stability of the nanocomposites compared to their original CPs. Moreover, all materials emitted efficiently in the solid state with luminescence enhancement and dependence on aggregation. Furthermore, these CPs and their nanoclays were checked as corrosion inhibitors against mild steel dissolution in acidic media. Cycloheptanone nanocomposites showed the highest inhibition efficiency (95.92%), confirming that the presence of nanoclays can enhance the CP’s ability to retard the corrosion by covering more surface area of the metal. This study presents ways to enhance the solubility, thermal stability, and corrosion inhibition efficiency of CPs using nanoclay modification. Additionally, these nanoclays may be used as solid-state luminescent materials and mixed inhibitors.

    更新日期:2018-09-09
  • Effect of AlR3 (R = Me, Et, iBu) addition on the composition and microstructure of ethylene/1-olefin copolymers made with post-metallocene complexes of group 4 elements
    Polym. J. (IF 2.17) Pub Date : 2018-09-07
    Julia Fryga, Marzena Białek

    The effect of trialkylaluminum compound (AlR3, where R = Me, Et, iBu) addition on the performance of the [LigZrCl]2(μ-O)/AliBu3/Ph3CB(C6F5)4 and LigTiCl2/AliBu3/Ph3CB(C6F5)4 (Lig = Me2N(CH2)2N(CH2-2-O-3,5-tBu2-C6H2)2) catalysts in ethylene/1-olefin copolymerization was investigated. The presence of AlMe3 in the feed during the copolymerization process catalyzed by the diamine-bis(phenolate) zirconium catalyst greatly increases the amount of incorporated comonomer and leads to microstructural changes, e.g., the formation of blocky and alternating sequences of 1-olefin units. Moreover, the use of AlMe3 limits the reaction yield and decreases the molecular weight of the produced copolymers. The catalytic properties of the diamine-bis(phenolate) titanium catalyst were much less affected by trimethylaluminum; its use slightly decreased the catalyst activity and copolymer molecular weight. A lower molecular weight was also detected for the copolymers produced by catalysts in the presence of both AlEt3 and AliBu3, whereas they did not cause any important changes in the catalytic activity, overall composition or microstructure of the produced copolymers. Copolymerization tests with other catalytic systems, (LigFI)2ZrCl2/AliBu3/Ph3CB(C6F5)4 (LigFI = (C6H5)N = CH(2-O-3,5-tBu2-C6H2)) and Et(Ind)2ZrCl2/MMAO, in the presence of AlMe3, were also carried out for the purpose of comparison.

    更新日期:2018-09-09
  • Novel phosphoric acid (PA)-poly(ether ketone sulfone) with flexible benzotriazole side chains for high-temperature proton exchange membranes
    Polym. J. (IF 2.17) Pub Date : 2018-09-05
    Mengqi Du, Li Yang, Xuan Luo, Kaili Wang, Guanjun Chang

    Poly(ether ketone sulfone)s with functionalized benzotriazole side chains are simply designed and successfully obtained by the copolycondensation of 4,4-difluorodiphenylsulfone, 4,4’-dihydroxydiphenylamine and a benzotriazole-based difluoro compound. The resulting polymers are identified by Fourier transform infrared spectroscopy and nuclear magnetic resonance, and the results are consistent with the proposed polymer structures. Owing to the intermolecular hydrogen bonding, the phosphoric acid (PA)-doped polymer membranes show encouraging mechanical properties. Taking advantage of the flexible movement of the benzotriazole in the side chains, the resulting membranes exhibit promising proton conductivities and fuel cell performance, which makes them a strong potential material for applications in high-temperature proton exchange membrane fuel cells.

    更新日期:2018-09-05
  • Adhesion force measurement of live cypris tentacles by scanning probe microscopy in seawater
    Polym. J. (IF 2.17) Pub Date : 2018-09-05
    Shohei Shiomoto, Yuka Yamaguchi, Kazuo Yamaguchi, Yasuyuki Nogata, Motoyasu Kobayashi

    The adhesion force of the tentacle of a live cypris on a glass surface covered with polymer brush was directly measured by scanning probe microscopy. Polymer brushes were prepared on the cover glass and silicon wafers by surface-initiated atom transfer radical polymerization of 3-(N-2-methacryloyloxyethyl-N,N-dimethyl)ammonatopropanesulfonate (MAPS) or 2-hydroxyethyl methacrylate (HEMA). A small amount of glue was placed at the edge of a tipless cantilever supported by the piezo motion control system of the scanning probe microscope and monitored by using an optical microscope. A live cypris swimming in seawater was held down on the slide glass by the cantilever for 30 min until the glue cured. The tentacles of the live cypris immobilized on the cantilever were forced to make contact with the surface-modified cover glass. The adhesion force was determined by the torsion of the cantilever when the tentacle was detached from the cover glass surface. The adhesion force between the cypris and the propylsilane-modified glass surface increased from 1.6 to 40 μN with the increase in age of the cypris larva from 3 to 21 days after metamorphosis from the nauplius larva. Poly(MAPS) and poly(HEMA) brush surfaces exhibited extremely low adhesion to the cypris larva during 21 days in seawater, indicating the effective antifouling property of hydrophilic polymer brushes.

    更新日期:2018-09-05
  • Hole-transporting diketopyrrolopyrrole-thiophene polymers and their additive-free application for a perovskite-type solar cell with an efficiency of 16.3%
    Polym. J. (IF 2.17) Pub Date : 
    Hirofumi Maruo, Yusuke Sasaki, Kohei Harada, Koki Suwa, Kenichi Oyaizu, Hiroshi Segawa, Kenneth Carter, Hiroyuki Nishide

    Conjugated polymers of diketopyrrolopyrrole (DPP) and thiophene, especially 2,5-di-2-thienyl-thieno[3,2-b]thiophene, were characterized based on their molecular packing orientation, and they showed a π–π stacking distance of 3.6 Å and a high field-effect hole mobility on the order of 10−2 cm2/Vs. Perovskite solar cells fabricated with the genuine or both oxidant- and salt dopant-free polymer as the hole-transporting layer displayed high photoconversion efficiencies of 16.3% as well as high durability.

    更新日期:2018-08-23
  • Confined film structure and friction properties of triblock copolymer additives in oil-based lubrication
    Polym. J. (IF 2.17) Pub Date : 2018-08-17
    Shinji Yamada, Ami Fujihara, Shin-ichi Yusa, Tadao Tanabe, Kazue Kurihara

    Abstract The friction properties of a dilute solution of block copolymer additives in poly-α-olefin (PAO) confined between mica surfaces were investigated using the surface forces apparatus. Friction measurements were made for poly(11-acrylamidoundecanoic acid)-block-poly(alkyl methacrylate)-block-poly(11-acrylamidoundecanoic acid) with an alkyl chain length of C12 (A5L946A5) in the poly(alkyl methacrylate) blocks. The results were compared to those for a PAO solution of a similar triblock copolymer with an alkyl chain length of C18 (A5S992A5) examined in our previous work (Yamada et al., Langmuir 2015). The friction coefficient μ for A5L946A5/PAO was approximately 0.5, which was one or two orders of magnitude larger than that for A5S992A5/PAO (μ of 0.002–0.039). Detailed analysis of the dynamic thickness and contact geometry enabled us to investigate the difference in the friction reduction abilities of the two additives. A5L946A5 has a high affinity to PAO and the molecules have expanded conformation in PAO; extensive chain entanglement effect results in the formation of a thick and viscous lubricant layer, which gives rise to high friction. On the other hand, A5S992A5 has low affinity to PAO, and the shrunken A5S992A5 molecules adsorbed on the surfaces form a rigid slip plane at the interface, which gives rise to low friction. Our results provide insights into the oil/additive combinations used for low friction in oil-based lubrication.

    更新日期:2018-08-17
  • Development of polymer field-effect transistor-based immunoassays
    Polym. J. (IF 2.17) Pub Date : 2018-08-16
    Tsukuru Minamiki, Yui Sasaki, Shiwei Su, Tsuyoshi Minami

    Polymer field-effect transistors (PFETs) are among the most fascinating electronic devices because of their attractive properties, such as durability, environmental friendliness, and solution processability. To date, PFETs have been employed for the development of flexible displays, radio-frequency identification tags, flexible non-volatile memories, among others. Moreover, due to the above advantages, PFETs can be applied to disposable on-site analytical devices. In that regard, we have developed extended-gate type PFETs with molecular recognition biomaterials for protein sensing in aqueous media. The fabricated PFETs were used to successfully detect glycoproteins (immunoglobulin A, immunoglobulin G, and chromogranin A) without any complicated labeling processes. Since our proposed immunoassay, which is performed on the basis of extended-gate type PFETs, is rapid and easy-to-use, PFET will be an attractive platform for on-site monitoring devices in healthcare applications in the near future.

    更新日期:2018-08-17
  • Highly porous polymer dendrites of pyrrole derivatives synthesized through rapid oxidative polymerization
    Polym. J. (IF 2.17) Pub Date : 2018-08-16
    Kanji Ishii, Kosuke Sato, Yuya Oaki, Hiroaki Imai

    Highly porous organic structures are synthesized by the oxidative polymerization of pyrrole derivatives in a concentrated monomer and oxidant solution. The rapid polymerization of pyrrole by oxidation with FeCl3 in CHCl3 as a cosolvent for the monomer and the oxidant leads to nanometer-scale branching morphologies that have a specific surface area of ~200 m2 g−1. The polymerization of pyrrole derivatives, such as 1-methylpyrrole and 1-ethylpyrrole, produced intragranular micropores of ~1 nm in diameter in the polymer grains of nanoscale dendrites. We obtained highly porous polymers of polypyrrole derivatives that have high specific surface areas (~900 m2 g−1) with bimodal pore-size distribution. The enhanced adsorbability of porous polymer dendrites for aromatic molecules was confirmed, in comparison with that of conventional polystyrene adsorbents.

    更新日期:2018-08-17
  • Effect of Li salt addition on electrochemical properties of poly(ethylene carbonate)-Mg salt electrolytes
    Polym. J. (IF 2.17) Pub Date : 2018-08-15
    Azlini Ab Aziz, Yoichi Tominaga

    We report the ion-conductive and electrochemical properties of solid polymer electrolytes (SPEs) based on poly(ethylene carbonate) (PEC) and magnesium bis(trifluoromethanesulfonyl)imide, Mg(TFSI)2, with the inclusion of small amounts of lithium bis(fluorosulfonyl)imide, LiFSI. The addition of LiFSI improved the ionic conductivity of PEC-Mg(TFSI)2 from ~2.3 × 10−6 S cm−1 to ~1.0 × 10−5 S cm−1 at 80 °C. Cyclic voltammetry revealed that the plating/stripping reaction of Mg is enhanced by the addition of LiFSI. Linear sweep voltammetry found that the addition of LiFSI has no negative influence on the electrochemical oxidation stability of the electrolyte, which reached 2 V vs. Mg/Mg2+. The addition of a small amount of LiFSI proves to be an effective method for enhancing the ion-conductive and electrochemical performance of PEC-based Mg electrolytes.

    更新日期:2018-08-15
  • Special issue: Self-assembled structures and materials for accessing new functions
    Polym. J. (IF 2.17) Pub Date : 2018-08-06
    Takeshi Serizawa, Atsushi Shishido, Christine K. Luscombe, Takashi Kato

    Special issue: Self-assembled structures and materials for accessing new functions Special issue: Self-assembled structures and materials for accessing new functions, Published online: 06 August 2018; doi:10.1038/s41428-018-0085-z Special issue: Self-assembled structures and materials for accessing new functions

    更新日期:2018-08-06
  • Cardiac differentiation of induced pluripotent stem cells on elastin-like protein-based hydrogels presenting a single-cell adhesion sequence
    Polym. J. (IF 2.17) Pub Date : 2018-08-03
    Yusuke Kambe, Takayuki Tokushige, Atsushi Mahara, Yasuhiko Iwasaki, Tetsuji Yamaoka

    Abstract Substrate-dependent cardiac differentiation of induced pluripotent stem cells (iPSCs) has been studied on various extracellular matrix (ECM)-derived substrates, such as collagen type I (Col-I). However, ECM-derived substrates have multiple cell-adhesive amino acid sequences and stimulate various signaling pathways in cells, making it difficult to clarify the mechanism of substrate-dependent stem cell differentiation. A substrate presenting one of these sequences is a powerful tool for elucidating the mechanism. We designed elastin-like proteins (ELPs) composed of repetitive VPGIG sequences with or without the RGD cell adhesion motif (ELP-RGD/ELP-Ctrl) and used a chemical crosslinker to generate hydrogels. By adjusting the ELP and crosslinker concentrations, we obtained ELP-Ctrl and ELP-RGD hydrogels with a Young’s modulus of 0.3 kPa. The ELP-Ctrl and ELP-RGD gels were used as a substrate for the cardiac differentiation of cultured murine iPSCs. Cells on the ELP-RGD gel showed four times higher gene expression of the contractile protein troponin T type 2 than those on a Col-I gel, which is an effective substrate for iPSC cardiac differentiation. The ELP-RGD gel might stimulate integrin-derived signaling pathways in the cells to promote cardiac differentiation. This study showed the potential of ELP hydrogels for studying substrate-dependent iPSC cardiac differentiation by enabling the control of cell-adhesive sequence presentation.

    更新日期:2018-08-03
  • Lyotropic ordering for high proton conductivity in sulfonated semialiphatic polyimide thin films
    Polym. J. (IF 2.17) Pub Date : 2018-08-03
    Kensaku Takakura, Yutaro Ono, Kota Suetsugu, Mitsuo Hara, Shusaku Nagano, Takashi Abe, Yuki Nagao

    The influence of the semialiphatic backbone on molecular ordering and proton conductivity was investigated in comparison to the rigid aromatic backbone in highly proton-conductive organized polyimide thin films. We newly synthesized two alkyl-sulfonated semialiphatic polyimides (ASSPIs) with different molecular weights and investigated their molecular organized structure, proton conductivity, water uptake, and the dissociation state of protons from sulfonic acid groups in thin films by in situ measurements for grazing incidence small-angle X-ray scattering (GISAXS), quartz crystal microbalance (QCM), fourier transform infrared (FT-IR) spectra, and impedance spectra. Declining planarity in the semialiphatic backbone reduced the aggregative character and molecular ordering in the lyotropic liquid-crystalline (LC) structure. However, the higher-molecular-weight ASSPI exhibited the oriented lamellar structure despite the lower planarity of the main chain. The proton conductivity of the oriented lamellar thin film had more than half an order of magnitude higher value of 1.5 × 10-1 S cm-1 than did the nonoriented lamellar thin film (3.0 × 10-2 S cm-1) at 25 °C and 95% RH. These results indicate that in sulfonated polyimide thin films, the lamellar orientation greatly contributes to the high proton conductivity in ASSPI thin films.

    更新日期:2018-08-03
  • Syntheses of carboxylated poly(arylene ether ketone)s with hyperbranched and linear architectures through the self-condensations of aromatic dicarboxylic anhydrides
    Polym. J. (IF 2.17) Pub Date : 2018-08-01
    Yuta Nabae, Nobuhiro Takusari, Kenta Yamamoto, Jun Mizuno, Teruaki Hayakawa, Masa-aki Kakimoto

    Carboxylated poly(arylene ether ketone)s with hyperbranched and linear architectures were synthesized by the self-condensations of aromatic dicarboxylic anhydrides. A linear poly(arylene ether ketone) was obtained from an AB monomer, 4-phenoxyphthalic anhydride, whereas a hyperbranched poly(arylene ether ketone) was obtained using an AB2 monomer, 1,3-bis(3,4-dicarboxyphenoxy)benzene dianhydride. The method for the synthesis of the hyperbranched poly(arylene ether ketone) is notable, because it provides a high ion-exchange capacity, above 7 mmol g−1, through a one-pot polycondensation. These functional polymers are soluble in several organic solvents and aqueous NaOH, in contrast to typical poly(ether ketone)s, while they retain the high thermal stabilities of their backbones.

    更新日期:2018-08-01
  • Properties and surface morphologies of organic–inorganic hybrid thin films containing titanium phosphonate clusters
    Polym. J. (IF 2.17) Pub Date : 2018-07-27
    Ryohei Hayami, Keisuke Wada, Yuta Miyase, Takuya Sagawa, Satoru Tsukada, Kazuki Yamamoto, Takahiro Gunji

    Organic–inorganic hybrid thin films containing [Ti4(μ3-O)(OiPr)5(μ-OiPr)3(O3PPh)3]·THF (TiOPPh) were prepared via the hybridization of TiOPPh with poly(vinyl phenol) (PVP), poly(styrene-co-allyl alcohol) (PSA), and poly(bisphenol A-co-epichlorohydrin) (PBE) using spin coating. These thin films were characterized in terms of their transmittance, pencil hardness, and surface morphologies. The transmittance values of the PVP hybrid thin films decreased with the addition of TiOPPh because of the formation of Ti–O–Ph bonds. The pencil hardness values of the hybrid thin films were in the order PVP > PBE > PSA hybrids. Using confocal laser scanning microscopy and atomic force microscopy, the pencil hardness values were determined to be strongly dependent on the surface morphology, such as the roughness and presence of pin holes. The model cluster was synthesized by the reaction of TiOPPh with excess ethanol to study the structures of the TiOPPh in hybrids. From the nuclear magnetic resonance spectroscopy and single-crystal X-ray structure analyses, the main core structure of the model cluster was found to retain the core structure of TiOPPh.

    更新日期:2018-07-27
  • The electrostatic advantages of cross-linked polystyrene organogels swollen with limonene for selective adsorption and storage of hydrophobic drugs
    Polym. J. (IF 2.17) Pub Date : 2018-07-20
    Preeyarad Charoensumran, Hiroharu Ajiro

    The organogels poly(styrene-co-divinylbenzene), PS gel (1); poly(styrene-co-divinylbenzene-co-vinylpyridine), PS-VP gel (2); poly(styrene-co-divinylbenzene-co-vinylbenzoic acid), PS-VBA gel (3); and poly(styrene-co-divinylbenzene-co-styrenesulfonate), PS-SS gel (4) were prepared with limonene by varying the concentration of cross-linker and comonomer to control the properties of the gels. Limonene was used as the swelling solvent due to its low toxicity and environmental friendliness. Additionally, 4-vinylpyridine (VP), 4-vinylbenzoic acid, and 4-styrenesulfonate were introduced as cationic and anionic moieties to act as interaction units. An increase in the divinylbenzene ratio improved the mechanical strength, as evidenced by an increase in the G′ value; for example, the G′ of gel 3 improved from 15,000 Pa with 5% cross-linking to 93,000 Pa with 10% cross-linking. However, the increased cross-linking reduced the solubility in limonene, resulting in a decrease in the swelling ratio from 1.5 to 0.7. Cationic gel 2 can adsorb anionic compounds, while anionic gel 4 can adsorb cationic compounds. Gel 2 with 5 mol% VP was able to adsorb approximately 4.4 mg/g of an anionic dye, while gel 4 with 5 mol% SS was able to adsorb approximately 6.6 mg/g of a cationic dye. The limonene organogels were used for lipophilic drug storage and the controlled release of testosterone due to their dense polymer network.

    更新日期:2018-07-21
  • Selective fabrication of hollow and solid polysaccharide composite fibers using a microfluidic device by controlling polyion complex formation
    Polym. J. (IF 2.17) Pub Date : 2018-07-19
    Kazutoshi Iijima, Shun Ohyama, Kazuya Yuyama, Atsushi Shono, Mineo Hashizume

    Natural polysaccharides are an important class of biomaterials that have attracted significant research interest for biomedical applications because of their high biocompatibility, biodegradability, and bioactivity. In this work, we fabricated water-insoluble composite hollow and solid fibers made of polyion complexes of chondroitin sulfate C (CS) and chitosan (CHI) using a single microfluidic device. A coaxial two-phase microfluidic device was constructed from stainless-steel needles and glass fibers, and CHI solutions and CS solutions were continuously infused into the core and sheath channels, respectively. The obtained fibers were flexible and homogeneous and had diameters of a few hundred micrometers. Hollow fibers were formed using water as the solvent of CS, while core-filled solid fibers were obtained using 20% (v/v) ethanol. The respective mechanisms for the fabrication of the hollow and solid fibers were discussed. An increase in the sheath flow rate or decrease in the core flow rate reduced the diameters of the fibers, while a reduction in the concentration of the CHI solution reduced the thickness of the hollow fibers. Furthermore, bovine serum albumin, used as a model protein, could be incorporated in the hollow and solid fibers by mixing them in the core flow solution. These results suggested the great potential of microfluidic techniques for the preparation of hollow and solid polysaccharide fibers.

    更新日期:2018-07-19
  • Transition of phase-separated PBTPA/PMMA solution droplets from core–shell to Janus morphology under UV light irradiation
    Polym. J. (IF 2.17) Pub Date : 2018-07-17
    Shu Kikuchi, Shinji Kanehashi, Kenji Ogino

    Here, we report the morphological transition of a phase-separated structure from core–shell to Janus morphology in droplets consisting of a poly(4-butyltriphenylamine) (PBTPA)/poly(methyl methacrylate) (PMMA) blend solution, induced by UV light irradiation. We obtained a phase-separated structure formed by the evaporation of the solvent from polymer solution droplets dispersed in an aqueous solution containing a surfactant. The rate of transition decreased with increasing polymer concentration and diameter of the droplet. It was also found that the transition was caused by UV light with a wavelength of 365 nm, which is mainly absorbed by PBTPA, indicating that this phenomenon is triggered by PBTPA. When the droplet was heated to 75 °C, no transition was observed.

    更新日期:2018-07-18
  • Solid-state polymerization of 1,4-bis(hexatriynyl)benzene derivatives
    Polym. J. (IF 2.17) Pub Date : 2018-07-17
    Keita Sasamura, Kei Mizuguchi, Yoko Tatewaki, Shuji Okada

    Two 1,4-bis(hexatriynyl)benzene derivatives with urethane groups, i.e., 10,10′-(1,4-phenylene)bis(5,7,9-decatriynyl N-(butoxycarbonylmethyl)carbamate) 1 and its perfluorophenylene derivative 2, were synthesized, and their solid-state photopolymerization was investigated. Upon UV irradiation, both of them showed excitonic absorption characteristic of polydiacetylene (PDA). In particular, 2 showed an absorption maximum at 743 nm, which was approximately 100 nm longer than that of conventional PDAs because of the effective conjugation between the polymer backbone and π-conjugated substituents. The conversion of 1 to the corresponding polymer was quite low. On the other hand, more than half of the hexatriynyl moieties of 2 were found to polymerize, indicating that most of the monomers were converted to the polymer upon prolonged UV irradiation.

    更新日期:2018-07-18
  • Surface and interface designs in side-chain liquid crystalline polymer systems for photoalignment
    Polym. J. (IF 2.17) Pub Date : 2018-07-13
    Shusaku Nagano

    In side-chain liquid-crystal (SCLC) polymer systems, the liquid crystalline (LC) mesogenic groups preferentially orient normal to the substrate plane due to the excluded volume effect (homeotropic alignment). Photoresponsive azobenzene (Az) mesogens have a transition moment parallel to the molecular long axis. Light irradiation for photoreactions is generally applied perpendicular to the film surface. Therefore, a homeotropic orientation inhibits efficient photoreactions and photoalignments in Az SCLC polymer systems. This review focuses on new approaches to induce a random planar orientation in Az SCLC polymer systems by interface and surface molecular design. The mesogens in a high-density SCLC polymer brush formed by surface-initiated living radical polymerization adopt a random planar orientation. In the film of an SCLC block copolymer with an amorphous block, a random planar orientation is induced via surface segregation of either of the blocks. The random planar orientations of SCLC polymer systems are thermally stable and offer efficient in-plane photoalignment and photoswitching with hierarchical LC molecular architectures, forming, e.g., microphase-separated (MPS) SCLC block copolymers and layered polymer LC systems. These surface and interface molecular designs are expected to provide new concepts and possibilities for LC polymer devices.

    更新日期:2018-07-14
  • Interfacial morphologies and associated processes of multicomponent polymers
    Polym. J. (IF 2.17) Pub Date : 2018-07-13
    Hiroshi Jinnai

    This review describes contemporary advancements in the study of interfacial morphologies and associated processes of multicomponent polymers. A particular emphasis is placed on the use of three-dimensional (3D) microscopy, for example, transmission electron microtomography (TEMT) and laser scanning confocal microscopy (LSCM). The time evolution of a spinodal interface during the phase separation of a polymer blend was followed by LSCM. The obtained 3D interfacial morphology was analyzed by differential geometry. The scalability was tested using curvature distributions. 3D nanoimaging, that is, TEMT, was applied to examine the stability and dynamics of complex block copolymer (BCP) morphologies, and novel structural data were directly assessed according to the 3D volume data. This review also examines two essential developments in the time-dependent in situ electron tomography of polymer materials to study the dynamic processes of BCPs. The 3D microscopy-based structural information renders an important perspective into the studies of nonlinear nonequilibrium occurrences as well as the statistical physics of long-chain-bearing moieties.

    更新日期:2018-07-14
  • Direct arylation polycondensation for synthesis of optoelectronic materials
    Polym. J. (IF 2.17) Pub Date : 2018-07-13
    Junpei Kuwabara

    Direct arylation polycondensation has been investigated to develop efficient methods for the preparation of conjugated polymeric materials for use in optoelectronic applications. The reaction conditions have been examined to achieve high molecular weights and minimal structural defects in the recurring structures. Under optimal conditions, the direct arylation method has several advantages over conventional methods, e.g., it has fewer synthetic steps and yields a high-molecular-weight and high-purity polymer. The high-quality polymeric materials that were obtained exhibited superior performance to those obtained using a conventional method when used in optoelectronic devices such as organic photovoltaics and field-effect transistors. Recent developments in C–H/C–H coupling polycondensation are also described.

    更新日期:2018-07-14
  • Size-tuned hydrogel network of palladium-confining polymer particles: a highly active and durable catalyst for Suzuki coupling reactions in water at ambient temperature
    Polym. J. (IF 2.17) Pub Date : 2018-07-12
    Hikaru Matsumoto, Takanori Akiyoshi, Yu Hoshino, Hirokazu Seto, Yoshiko Miura

    Poly(N-isopropylacrylamide)-based hydrogel particles (GPs) with different sized hydrogel networks were developed and used to confine a palladium (Pd) catalyst. The size of the gel network was tuned by varying the feed ratio of the cross-linking monomer. Nanosized-Pd(0) was loaded into the GPs, which contain a tertiary-amine ligand, via Pd-ion adsorption and subsequent reduction. The Pd-loaded GPs were used as the catalyst for a Suzuki coupling reaction between phenylboronic acid and 4-bromobenzoic acid in water at 30 °C. Due to the hydrophilic reaction platform provided by the hydrogel matrix of the GPs, the catalytic efficiencies of Pd-loaded GPs were significantly higher than those of commercially available Pd-loaded supports. Notably, the Pd-loaded GPs with the smallest gel networks were highly durable for Suzuki coupling reactions. It is plausible that the smaller network minimized or prevented the enlargement of Pd(0) during the catalytic cycle. The facile synthesis of the GPs, environmentally benign catalytic system, and high catalytic durability and activity of these Pd-loaded GPs are all important factors for the industrial application of these materials.

    更新日期:2018-07-12
  • Advanced flavin catalysts elaborated with polymers
    Polym. J. (IF 2.17) Pub Date : 2018-07-10
    Yukihiro Arakawa, Keiji Minagawa, Yasushi Imada

    A variety of biological redox reactions are mediated by flavoenzymes due to the unique redox activity of isoalloxazine ring systems, which are found in flavin cofactors. In the field of synthetic organic chemistry, the term “flavin” is generally used for not only isoalloxazines but also related molecules including their isomers and some analogs, and those having catalytic activity are called flavin catalyst. 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. We recently became interested in using polymers for the development of flavin catalysts, especially to improve their practicality and advance the field of catalysis. Here, we summarize our recent research on such flavin–polymer collaborations 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.

    更新日期:2018-07-12
  • Grain coarsening on the free surface and in the thickness direction of a sphere-forming triblock copolymer film
    Polym. J. (IF 2.17) Pub Date : 2018-07-06
    Rasha Ahmed Hanafy Bayomi, Konomi Honda, Isao Wataoka, Hideaki Takagi, Nobutaka Shimizu, Noriyuki Igarashi, Sono Sasaki, Shinichi Sakurai

    Controlling a block copolymer “grain”, in which the microdomains are regularly ordered in a single lattice, is important for developing high-performance polymeric materials. This is because the grains, which are several micrometers in size, can directly affect the properties of the materials. In this regard, we focused on grain coarsening on the free surface and in the thickness direction of a sphere-forming triblock copolymer film. We evaluated the grain size on the free surface using atomic force microscopy combined with image processing, and in the thickness direction, we used small-angle X-ray scattering edge-view measurements. It was found that the grain growth in the direction parallel to the free surface was very slow in the early stage of thermal annealing. Then, the grain growth shifted to a rapid growth mechanism with a power-law relationship (grain size ~tα, with α = 0.7) after ~30 min. Based on the value of the growth exponent α, the grain growth mechanism is considered to fall between the random and deterministic processes. In contrast, for the thickness direction, a much larger value (α = 1.72) was obtained. For such a large α value, it is impossible to consider the growth mechanism of the grain within the conventional to framework of the growth of domains and droplets. Therefore, our results may require a new framework to explain the behavior of the grain growth in the spherical microdomain system. Another notable finding is that the thickness of the oriented layer near the free surface or near the surface in contact with the substrate can be as thick as 9.5 µm, which is substantially larger than the reported values of the propagation distance of surface-induced orientation of microdomains in block copolymers. Based on the results of the current study, it is speculated that grain growth serves as a propagator for the regular ordering of spherical microdomains and the orientation of the lattice.

    更新日期:2018-07-08
  • Functional polymers from renewable plant oils
    Polym. J. (IF 2.17) Pub Date : 2018-07-05
    Hiroshi Uyama

    This focus review addresses recent progress on plant oil-based functional polymers and composites. Plant oils are one of the most ideal chemical feedstocks to replace fossil resources for a variety of industrial chemicals in the polymer industry. In this focus review, 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, mainly epoxidized soybean oil, 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. These plant oil-based materials are significant for the molecular design of functional and high-performance biobased products for industrial applications to contribute to the reduction of greenhouse emissions.

    更新日期:2018-07-08
  • Structure−property relationships of polypropylene-based nanocomposites obtained by dispersing mesoporous silica into hydroxyl-functionalized polypropylene. Part 2: Matrix−filler interactions and pore filling of mesoporous silica characterized by evolved gas analysis
    Polym. J. (IF 2.17) Pub Date : 2018-07-04
    Ryota Watanabe, Hideaki Hagihara, Hiroaki Sato

    Nanocomposites containing mesoporous silica (MPS) materials with various pore structures (SBA-15 and MCM-41 types) melt mixed into polypropylene (PP) or PP functionalized with hydroxyl groups (PPOH) were characterized by analytical pyrolysis techniques, such as evolved gas analysis (EGA)-mass spectrometry (MS) and heart-cut EGA-gas chromatography (GC)/MS, to evaluate the interactions between the polymer matrix and MPS and the pore filling of the MPS in the nanocomposite. The EGA-MS measurements revealed that nanocomposites with MPSs evolve specific degradation products, which can be attributed to strong interactions between the polymer molecules and the internal pores. The amount of these specific products increased upon increasing the pore size of the MPS and the hydroxyl content in the polymer matrix. Sufficiently large pores of MPS and high hydroxyl contents in the matrix appear to provide strong interactions because the MPS pores are well-filled with polymer molecules, which contributes to the improved physical properties of the nanocomposites.

    更新日期:2018-07-05
  • Molar mass dependence of structure of xanthan thermally denatured and renatured in dilute solution
    Polym. J. (IF 2.17) Pub Date : 2018-07-03
    Yasuhiro Matsuda, Kazuya Okumura, Shigeru Tasaka

    Double helical polysaccharide, xanthan samples with varying molar mass were thermally denatured and renatured in dilute solutions. Both the weight average molar mass, which was determined by size exclusion chromatography (SEC), and viscosity average molar mass decreased after denaturation and renaturation for samples with an initial molar mass of 106 g mol−1, but those for the samples with an initial molar mass of 105 or 107 g mol−1 decreased only slightly. Although the double helices of xanthan only partially dissociated into single chains, the molar mass distribution estimated by SEC did not broaden drastically by the denaturation and renaturation. These results can be explained by the formation of hairpin structures by the single chains, which are restricted to xanthan with a molar mass of 105 g mol−1 by the strain of the hairpin loop, and for xanthan molar masses of 107 g mol−1 by the incomplete dissociation of its long polymer chains.

    更新日期:2018-07-04
  • Structure-property relationships of polypropylene-based nanocomposites obtained by dispersing mesoporous silica into hydroxyl-functionalized polypropylene. Part 1: toughness, stiffness and transparency
    Polym. J. (IF 2.17) Pub Date : 2018-06-26
    Ryota Watanabe, Hideaki Hagihara, Hiroaki Sato

    The long-range objective of this study is to provide better understanding of the relationship between the structures and properties of PP-based nanocomposites containing mesoporous silica (MPS). In this investigation, nanocomposites composed of MPSs with various porosity structures (two types of Santa Barbara Amorphous No. 15 (SBA-15) with pores of 4.4 or 8.0 nm, and Mobile Composition of Matter No. 41 (MCM-41) with pores of 2.9 nm) and polypropylene (PP) or functionalized PP containing hydroxyl groups (PPOH) were developed. Their physical properties were then evaluated. The nanocomposite containing PPOH and SBA-15 with a large pore size (SBA-15-L) showed higher toughness, stiffness, and transparency than the other nanocomposites. Our results indicated that the larger pore size of SBA-15-L and the high affinity between PPOH and the MPS surface led to an efficient pore-filled state of SBA-15-L with polymer molecules, forming a nanocomposite with better mechanical strength and transparency.

    更新日期:2018-06-27
  • Cocrystallization of monomer units of biobased and biodegradable Poly(l-lactic acid-co-glycolic acid) random copolymers
    Polym. J. (IF 2.17) Pub Date : 2018-06-20
    Hideto Tsuji, Koudai Kikkawa, Yuki Arakawa

    Random copolymers of l-lactic acid (LLA) and glycolic acid (GA) [P(LLA-GA)] with 0–100 mol% LLA units in the polymers were synthesized and their crystallization behavior was investigated by two representative crystallization methods of precipitation or melt-crystallization. P(LLA-GA) copolymers with LLA unit contents in the ranges of 0–20 and 73–100 mol% were crystallizable during precipitation or melt-crystallization. Surprisingly, these crystallizable ranges are similar to those reported for P(LLA-GA) copolymers synthesized by ring-opening polymerization of cyclic dimers (l-lactide and glycolide), which should have monomer sequence lengths twice those of the P(LLA-GA) copolymers synthesized by polycondensation of the monomers (LLA and GA) in the present study and are expected to have wider crystallizable ranges. The GA units of the LLA-rich P(LLA-GA) copolymers were incorporated in a lattice of LLA unit segments, whereas the LLA units of the GA-rich P(LLA-GA) copolymers were incorporated in a lattice of GA unit segments. Even the incorporation of relatively small-sized GA units in relatively large-sized LLA unit segments strongly induced structural disorder in the crystalline lattice. The crystalline size and melting temperature of the P(LLA-GA) copolymers decreased dramatically as the LLA unit content deviated from 0 to 100 mol%.

    更新日期:2018-06-20
  • Preparation of polymer brushes with well-controlled stereoregularity and evaluation of their functional properties
    Polym. J. (IF 2.17) Pub Date : 2018-06-18
    Tomoyasu Hirai, Masanao Sato, Tomoki Kato, Hitoshi Shimamoto, Kiyu Uno, Nobuyuki Otozawa, Atsushi Takahara

    Polymer brushes in which one polymer chain end is tethered to a substrate show permanent properties related to the chemical structure of the polymer. However, they cannot accommodate functional molecules in the desired space because of the steric hindrance between neighboring polymer chains. To overcome this problem, the preparation of polymer brushes with ordered nanopores is strongly desired. High-density poly(methyl methacrylate) 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 to 400 K with a narrow polydispersity index 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.

    更新日期:2018-06-19
  • Polymers healed autonomously and with the assistance of ubiquitous stimuli: how can we combine mechanical strength and a healing ability in polymers?
    Polym. J. (IF 2.17) Pub Date : 2018-06-15
    Chaehoon Kim, Naoko Yoshie

    Among various approaches to create self-healing polymers, the introduction of dynamic bonds to polymers is one of the most powerful approaches. Macroscopic failure of such polymers is usually accompanied by the cleavage of dynamic bonds at the broken surfaces, which can then reform due to their reversible nature and repair the failure. However, since the reformation of dynamic bonds requires molecular mobility, autonomous healing at room temperature is almost completely limited to polymers with good molecular mobility, such as gels and soft elastomers. Mechanical strength usually conflicts with a high molecular mobility, as well as an autonomous healing ability. In this review, we first overview recent successful approaches to overcome this limitation. These approaches include combining careful dynamic bond chemistry choices and smart designs of the environment around the dynamic bonds. In the latter part of this review, attempts to design mechanically robust polymers that can heal with the assistance of ubiquitous stimuli are summarized. Such a healing process is a suboptimal choice for practical, valuable healing materials.

    更新日期:2018-06-15
  • Preparation of an ethylene glycol-based block copolymer consisting of six different temperature-responsive blocks
    Polym. J. (IF 2.17) Pub Date : 2018-06-15
    Yoko Kudo, Hiromitsu Mori, Yohei Kotsuchibashi

    An ethylene glycol-based hexa-block copolymer with six different temperature-responsive blocks was prepared via a reversible addition-fragmentation chain transfer (RAFT) polymerization. 2-(2-methoxyethoxy)ethyl methacrylate (MEO2MA) and oligo(ethylene glycol) methacrylate (OEGMA) were selected as the ethylene glycol-based monomers. Each block of the hexa-block copolymer has a different OEGMA content and thus exhibits a different lower critical solution temperature (LCST). The structures of the block copolymers are similar to gradient copolymers. The molecular weights of the copolymers increased with the number of blocks (first block (P(MEO2MA)): 2800 g/mol, di-block copolymer: 7400 g/mol, tri-block copolymer: 12,000 g/mol, tetra-block copolymer: 18,500 g/mol, penta-block copolymer: 26,800 g/mol, and hexa-block copolymer: 40,400 g/mol) with relatively narrow molecular weight distributions (1.18–1.42). Each block exhibits a different LCST in aqueous solution owing to their different OEGMA contents. To the best of our knowledge, this is the first report of a block copolymer containing more than four types of temperature-responsive blocks. The temperature-responsive properties of the prepared block copolymers were investigated by UV-vis spectroscopy, micro-differential scanning calorimetry, and scanning electron microscopy.

    更新日期:2018-06-15
  • Design and development of a robust photo-responsive block copolymer framework for tunable nucleic acid delivery and efficient gene silencing
    Polym. J. (IF 2.17) Pub Date : 2018-06-11
    Thomas H. Epps III, Thu Vi, Millicent O. Sullivan

    Nucleic acid delivery offers tremendous potential for the treatment of acquired and hereditary diseases. Despite limited successes, the use of nucleic acid therapies has been hampered by the lack of safe and efficient delivery approaches. To address this challenge, Epps, Sullivan, and coworkers developed a new nucleic acid delivery framework predicated on a photo-responsive cationic block copolymer (BCP) that enabled tunable nucleic acid binding and precise spatiotemporal control over gene expression. This innovative platform, in which the polymer moieties directly responsible for nucleic acid complexation could be cleaved from the polymer upon photo-stimulation, significantly enhancing nucleic acid release. Furthermore, temporal control over polyplex disassembly facilitated the development of a simple, and potentially universal, kinetic modeling scheme for intracellular small interfering RNA (siRNA), messenger RNA, and protein concentrations, and that model was quantitatively validated using various genes across several animal cell lines and human primary cells. This versatile BCP-based framework easily accommodated: anionic excipients that increased siRNA potency by ~200% (on a per mass basis) over comparable polyplex systems; quantum dots that unlocked theranostic applications without impacting silencing performance; and small-molecule lipid co-formulations that enhanced transfection in human primary cells. Altogether, the system described herein shows great promise for the clinical translation of gene therapeutics.

    更新日期:2018-06-11
  • Photoinduced reinforcement of supramolecular gels based on a coumarin-containing gelator
    Polym. J. (IF 2.17) Pub Date : 2018-06-08
    Kazuhiro Yabuuchi, Nanako Matsuo, Hiroshi Maeda, Masaya Moriyama

    The mechanical strength of supramolecular gels is usually low compared to that of cross-linked polymer gels, which sometimes limits practical applications of supramolecular gels. We report here photoinduced reinforcement of supramolecular gel structures using photodimerization of coumarin moieties introduced on a trans-(1R,2R)-1,2-cyclohexanediamine-based gelator. UV irradiation (λ > 300 nm) of toluene gels containing mixtures of trans-(1R,2R)-1,2-cyclohexanediamine-based gelators with and without coumarin moieties induced an enhancement in both the thermal and mechanical stabilities of the gels.

    更新日期:2018-06-08
  • On-demand easy peeling of acrylic adhesives containing ionic liquids through a microwave irradiation stimulus
    Polym. J. (IF 2.17) Pub Date : 2018-06-07
    Mirei Usuba, Chizuru Hongo, Takuya Matsumoto, Takashi Nishino

    We prepared microwave-responsive “on-demand-peeling” adhesives simply by mixing second-generation acrylic adhesives with ionic liquids. A rapid response (<30 s for adhesive failure) to microwave irradiation was achieved using a microwave oven. This “on-demand-peeling” was attributed to local heating of the ionic liquid in the adhesive by microwave irradiation. In addition, the adhesive strength was not influenced by the ionic liquid additives without microwave irradiation. We revealed that the local heating and the plasticizing effect of the ionic liquid were the cause of the “on-demand-peeling”. Our preparation method for these microwave-responsive adhesives is simple, conventional, and attractive for the fundamental and industrial fields.

    更新日期:2018-06-07
  • Binding sites and structure of peptides bound to SiO2 nanoparticles studied by solution NMR spectroscopy
    Polym. J. (IF 2.17) Pub Date : 2018-06-07
    Yu Suzuki, Heisaburo Shindo

    Understanding the mechanism of the interaction between inorganic materials and peptides is important for the development of organic/inorganic hybrid materials. The titanium-binding peptide (TBP; Arg1-Lys2-Leu3-Pro4-Asp5-Ala6) has been reported to possess a high binding affinity to SiO2 as well as TiO2 surfaces. Here, we report the binding modes and mechanism of the TBP to SiO2 nanoparticles. To accomplish this objective, we analyzed the binding sites of the TBP to a SiO2 surface and the structure of the TBP bound to the SiO2 using solution NMR spectroscopy. Saturation transfer difference (STD) NMR analysis was performed to identify the TBP sites that interact with the SiO2 surface, and then Arg1 and Asp5 were identified to be in close contact with the SiO2 surface. The structure of the TBP bound to SiO2 was well defined, and the Arg1 and Asp5 side chains face in the same direction. The combination of these results validates that the guanidyl group of Arg1 and the carboxyl group of Asp5 interact electrostatically with the silanol groups SiO− and SiOH2+ on the SiO2 surface, respectively. The binding mode of TBP/SiO2 was found to be different from that of the TBP/TiO2 system, which has been previously reported.

    更新日期:2018-06-07
  • Soft materials based on colloidal self-assembly in ionic liquids
    Polym. J. (IF 2.17) Pub Date : 2018-06-06
    Kazuhide Ueno

    Ionic liquids (ILs) have attracted much attention as dispersion media for colloidal systems as alternatives to organic solvents and electrolyte solutions. Although colloidal stability is an essential factor for determining the properties and performance of colloidal systems containing ILs, detailed mechanisms for colloidal stabilization have not yet been studied. In the first part of this paper, we highlight our fundamental studies on colloidal stability. Three different repulsive forces, electrostatic, solvation, and steric interactions, are examined for their effectiveness in stabilizing colloidal particles in ILs. In the second part of this report, we provide an overview of our recent studies on colloidal soft materials in the presence of ILs. On the basis of the suspended state of the silica colloid particles, two different soft materials, a colloidal gel and a 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.

    更新日期:2018-06-06
  • Synthesis and thermal investigation of phosphate-functionalized acrylic materials
    Polym. J. (IF 2.17) Pub Date : 2018-06-06
    Yun-Fen Peng, Ashley Tsai, Ming-Hsi Huang

    Functionalized acrylic materials derived from methyl methacrylate (MMA), 2-hydroxyethyl methacrylate (HEMA), and diethyl 2-(methacryloyloxy)ethyl phosphate (DMP) were synthesized by successive free-radical polymerizations using benzoyl peroxide (BPO) as the initiator and N,N-dimethyl-p-toluidine (DMpT) as the activator. NMR and GPC data showed that successful random copolymerization of MMA and DMP was carried out using the BPO-DMpT system. Moreover, the resulting products were able to react with HEMA monomer, yielding polymers with P(MMA-co-DMP)-b-PHEMA chain structures. Interestingly, the glass transition of DMP/PHEMA-containing copolymers was reduced with respect to the PMMA homopolymer. In addition, the thermal stability was enhanced with increasing DMP content in P(MMA-co-DMP) copolymers and was further enforced by incorporating PHEMA blocks. The presence of DMP/PHEMA segments should improve the thermal behavior of acrylic materials, which is of great interest in the design of versatile bone cements for total joint arthroplasty and functional coatings in targeted drug delivery.

    更新日期:2018-06-06
  • Water near bioinert self-assembled monolayers
    Polym. J. (IF 2.17) Pub Date : 2018-06-06
    Ryongsok Chang, Syifa Asatyas, Ganchimeg Lkhamsuren, Makoto Hirohara, Evan Angelo Quimada Mondarte, Kasinan Suthiwanich, Taito Sekine, Tomohiro Hayashi

    For a long time, water has been speculated to play an essential role in the interactions of proteins and cells with artificial biocompatible materials. The current question is how water molecules at the interfaces affect the adsorption of proteins and the adhesion of cells. To answer this question, we introduce recent works that investigated the interfacial behavior of water near self-assembled monolayers (SAMs) by different types of analytical techniques. By combining these findings, we discuss how interfacial water affects the protein and cell resistance of various bioinert SAMs.

    更新日期:2018-06-06
  • Butylated lignin as a compatibilizing agent for polypropylene-based carbon fiber-reinforced plastics
    Polym. J. (IF 2.17) Pub Date : 2018-06-06
    Hiroki Sakai, Kosuke Kuroda, Takayuki Tsukegi, Tomoki Ogoshi, Kazuaki Ninomiya, Kenji Takahashi

    Lignin is a renewable resource, but it is also considered a waste or a very-low-value material. Herein, we propose a lignin-derived compatibilizing agent as an alternative to the current compatibilizing agents. We prepared a polypropylene-based carbon fiber-reinforced plastic (CFRP) with butylated lignin (C4 lignin). Upon the addition of C4 lignin, the dispersion of carbon fiber into the matrix, and the adhesion between the carbon fiber and the matrix were greatly improved. As a result, the tensile strength of the CFRP prepared with C4 lignin was greater than that of the CFRP without lignan lignin (37.1 compared to 40.2 MPa). This value is close to that of CFRPs prepared with maleic anhydride-modified polypropylene (40.9 MPa), an existing compatibilizing agent. C4 lignin is a promising candidate for biomass-derived compatibilizing agents for polypropylene-based CFRPs.

    更新日期:2018-06-06
  • Enhancement of the glass transition temperature of poly(methyl methacrylate) by salt
    Polym. J. (IF 2.17) Pub Date : 2018-06-05
    Asae Ito, Panitha Phulkerd, Viknasvarri Ayerdurai, Mizuki Soga, Antoine Courtoux, Azusa Miyagawa, Masayuki Yamaguchi

    We investigated the effects of two metal salts, lithium trifluoromethanesulfonate (LiCF3SO3) and lithium bromide (LiBr), on the glass transition temperature (Tg) of poly(methyl methacrylate) (PMMA). Both LiCF3SO3 and LiBr greatly enhanced the Tg of PMMA under dry conditions. However, once the sample films were exposed to humidity, the PMMA containing LiCF3SO3 absorbed a large amount of water, which acts as a plasticizer. As a result, the Tg shifted to a lower temperature, which limits the utility of this polymer in industrial applications. In contrast, the Tg of PMMA containing LiBr was minimally affected by the absorption of water. This phenomenon can be explained by the ion–dipole interactions with the small number of dissociated lithium cations.

    更新日期:2018-06-05
  • Morphology and optoelectronic characteristics of organic field-effect transistors based on blends of polylactic acid and poly(3-hexylthiophene)
    Polym. J. (IF 2.17) Pub Date : 2018-06-05
    Chia-Jung Cho, Shu-Yuan Chen, Chi-Ching Kuo, Loganathan Veeramuthu, Ai-Nhan Au-Duong, Yu-Cheng Chiu, Shang-Hung Chang

    This study investigates the influence of the solvent used to prepare films of a poly(3-hexylthiophene) (P3HT) and poly(lactic acid) (PLA) blend on the morphology and charge transport mobility of field-effect transistors (FETs). Films prepared from CH2Cl2, a poor solvent for P3HT, tended to form well-defined nanowires, attributable to P3HT self-assembly via a solubility-induced process. This phenomenon resulted in a mobility of 5.30 × 10−3 cm2 (Vs)−1 and an on/off ratio of 3.23 × 103 in a CH2Cl2-solvent P3HT/PLA-blend system with a P3HT content of 10 wt%. Even a blend with 2 wt% P3HT exhibited a mobility of 1.76 × 10−3 cm2 (Vs)−1. However, in blend systems where CHCl3 solvent was employed in film preparation, the mobility decreased as the PLA content increased, and almost no electrical characteristics were exhibited at 50 wt% P3HT due to the isolated, spherical, phase-separated morphology of P3HT aggregation. Moreover, in CH2Cl2 solvent systems, the mobility of the P3HT/PLA (10/90) blend decreased from 5.3 × 10−3 cm2 (Vs)−1 (in a glove box) to 3.7 × 10−3 cm2 (Vs)−1 (after 28 days of air exposure), whereas that of 100 wt% P3HT declined by approximately one order of magnitude. These results confirm that P3HT/PLA blends prepared from CH2Cl2 solvent can be used to fabricate environmentally friendly, low-cost FETs with favorable air stability.

    更新日期:2018-06-05
  • PJ ZEON Award for outstanding papers in Polymer Journal 2017
    Polym. J. (IF 2.17) Pub Date : 2018-06-05
    Takashi Kato

    PJ ZEON Award for outstanding papers in Polymer Journal 2017 PJ ZEON Award for outstanding papers in Polymer Journal 2017, Published online: 05 June 2018; doi:10.1038/s41428-018-0048-4 PJ ZEON Award for outstanding papers in Polymer Journal 2017

    更新日期:2018-06-05
  • Publisher Correction: Functional polymers in nonpolar solvents induced by dissociation of macromolecular complexes
    Polym. J. (IF 2.17) Pub Date : 2018-06-05
    Kazuki Sada

    Publisher Correction: Functional polymers in nonpolar solvents induced by dissociation of macromolecular complexes Publisher Correction: Functional polymers in nonpolar solvents induced by dissociation of macromolecular complexes, Published online: 05 June 2018; doi:10.1038/s41428-018-0063-5 Publisher Correction: Functional polymers in nonpolar solvents induced by dissociation of macromolecular complexes

    更新日期:2018-06-05
  • Monodisperse engineered PEGs for bio-related applications
    Polym. J. (IF 2.17) Pub Date : 2018-06-01
    Kazushi Kinbara

    The importance of monodisperse poly(ethylene glycols) (PEGs) and their derivatives is rapidly increasing. Focusing on the merits of heterobifunctional PEGs, we developed a chromatography-free procedure for the preparation of monodisperse monotosylated PEGs. This technique enables the preparation of 8- to 16-mers in relatively large quantities, with good yields and purities, and facilitates the investigation of PEG-based functional molecules. For example, we synthesized structured PEGs consisting of monodisperse PEGs and polyols, which had specific two-dimensional shapes. These structured PEGs exhibited unique properties in aqueous environments; the triangular molecule dehydrated at a lower temperature than linear compounds with a similar molecular weight and could thus suppress the aggregation of proteins at high temperatures. We also found that the introduction of an aromatic group into the PEG skeleton lowered the dehydration temperature, which decreased the critical solution temperatures (LCSTs). Recent achievements in the development of engineered poly(ethylene glycol)s (PEGs) will be highlighted in this review.

    更新日期:2018-06-01
  • Synthesis of polymers carrying adamantyl substituents in side chain
    Polym. J. (IF 2.17) Pub Date : 2018-06-01
    Takashi Ishizone, Raita Goseki

    This review addresses the synthesis of various polymers carrying bulky and rigid adamantyl substituents in their side chains. Synthetic methods for these polymers include typical polymer reactions of introducing adamantyl groups into existing polymers and the polymerization of monomers bearing pendant adamantyl groups. In particular, with regard to the latter synthetic method, the addition polymerization of adamantyl-containing vinyl monomers such as α-olefins, acetylenes, (meth)acrylates, (meth)acrylamides, vinyl ethers, 1,3-dienes, and styrenes is described. A variety of vinyl monomers are capable of undergoing living anionic polymerization to afford polymers with predictable molecular weights and narrow molecular weight distributions (M w/M n = 1.1). In several cases, the introduced adamantyl groups afford steric hindrance to prevent side reactions and control the addition modes of the polymerization. In general, the resulting adamantyl-substituted polymers show extremely high glass transition temperatures and high thermal stability derived from the stiff adamantyl substituents compared with the corresponding parent polymers.

    更新日期:2018-06-01
  • Synthesis of sulfone-containing non-ionic polyurethanes for electrophoretic deposition coating
    Polym. J. (IF 2.17) Pub Date : 2018-06-01
    Akinori Ohno, Mikihiro Hayashi, Akinori Takasu

    The desire to develop a sustainable society has recently inspired polymer chemists to explore functional polyurethane materials because of their versatile material shape and thermoplasticity. To develop further functionalities of polyurethane materials and manipulation methods, here, we report the synthesis and a new method for coating non-ionic polyurethanes containing sulfonyl groups with utilizing electrophoretic deposition. The polyurethanes were synthesized via polyaddition of methylenediphenyl 4,4′-diisocyanate (MDI) with 2,2′-thiodiethanol in the absence or presence of triethylene glycol (TEG) as the soft ternary segment of the polymer, followed by oxone oxidation. The electrophoretic behaviors of the polyurethanes toward a stainless-steel electrode were investigated, and the peeling resistance and scratch resistance of a polyurethane film coated on a plate were evaluated by cross-cut adhesion and pencil hardness tests, respectively. These tests revealed that incorporation of soft TEG segments at an appropriate fraction can enhance both peeling resistance and scratch resistance. We also tested the enhancement in the transparency of the coated films, which do not lose their favorable peeling resistance and scratch resistance in the process, by replacing the aromatic diisocyanate component (MDI) with an alicyclic diisocyanate, dicyclohexylmethane 4,4′-diisocyanate (HMDI).

    更新日期:2018-06-01
Some contents have been Reproduced with permission of the American Chemical Society.
Some contents have been Reproduced by permission of The Royal Society of Chemistry.
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