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  • We investigated the effect of the hydrophobicity of the side chains of mixed-charge polymers on their interaction with cancer cell membranes. Six pH-responsive mixed-charge polymeric micelles consisting of cationic, anionic, and neutral moieties were created, with differences in hydrophobicity generated by altering the type of anionic monomer and the ratio of the hydrophobic spacer moiety. Evaluation of their affinity for cell membranes revealed that increases in the hydrophobicity and pH-responsive nature led to pH-selective toxicity, which was assumed to be caused by the disruption of cell membrane integrity.

    • Yubuki Nakamura
    • Marina Nasu
    • Yuki Hiruta
    Original Article
  • Time-resolved FTIR was used to study the crystallization kinetics of syndiotactic polystyrene. Isothermal crystallization from the melt by cooling and from the glass by heating was used to determine the temperature (Tc) dependence of the crystallization rate (k). Based on the derived k and the crystal growth rates (G) obtained from OM and depolarized light scattering, the density of primary nucleation was readily calculated. The magnitudes of the nucleation densities in the cold-crystallized samples were ~5−6 orders higher than those of the melt-crystallized samples despite the similar k values.

    • Chun-Yu Lo
    • Chi Wang
    Original Article
  • Distannylated dithiazologermole and germaindacenodithiazole were copolymerized with dibrominated benzothiadiazole and di(thiazolyl)benzothiadiazole to produce four new donor-acceptor conjugated copolymers. The optical, electrochemical, and thermal properties of the copolymers were characterized. DFT calculations revealed that these thiazole-containing copolymers possessed lower HOMOs and LUMOs than those of thiophene-based congeners, in accordance with the experimental results. The intramolecular noncovalent S‒N and N‒H bond interactions and the effects of the bridging atom (C or Ge) on the HOMO and LUMO energy levels were also suggested by the DFT calculations.

    • Weipeng Sun
    • Yohei Adachi
    • Joji Ohshita
    Original Article
  • Catechol-modified alginates (AlgDAs) with various catechol contents were synthesized and examined as adhesive materials. AlgDA exhibited high adhesive strength with mica and moderate adhesive strength with polymer resins, although this adhesiveness was not observed for sodium alginate. AlgDA with a relatively low catechol content exhibited relatively high adhesive strength, unlike other catechol-modified polymer adhesives. AlgDA residues were successfully removed from the used substrates by a simple water washing process. AlgDA is promising as a biobased adhesive material that contributes to a sustainable society.

    • Soi Inata
    • Hiromitsu Sogawa
    • Fumio Sanda
    Original Article
  • Sustainable and 100% biobased plastics, polyamide 11 (PA11), derived from nonedible plants are mixed with polypropylene (PP) and a reactive compatibilizer in a twin-screw extruder. It is found that PP/PA11 bioalloys exhibited surprisingly good impact strength without losing flexural modulus only when the morphology of the PP/PA11 bioalloys was well controlled at nano-meter level, such as “nano-salami” structure. This leads to overcome a past and traditional issues in biobased plastics, resulting in applying for automobile plastic parts. This technology would contribute to realizing “carbon neutrality”.

    • Jumpei Kawada
    • Masayuki Kitou
    • Keisuke Kato
    Technical Review
  • We fabricated polymer brushes using a novel concept, which involves block copolymer segregation from the polymer region at the water interface. The resulting polymer brush is called a dynamic polymer brush because block copolymer segregation is a dynamic process that occurs at room temperature and is activated through contact with water. Dynamic polymer brushes undergo self-organization in the processes of self-assembly and self-healing (if destroyed). The concept and physical characteristics of dynamic polymer brushes are discussed in this review.

    • Hideaki Yokoyama
    Focus Review Open Access
  • A series of amphiphilic diblock copolymers (PVAm-b-PVPin: m/n = 82/6, 72/26, and 70/74) with different block lengths of hydrophilic poly(vinyl alcohol) (PVA) and hydrophobic poly(vinyl pivalate) (PVPi) blocks were prepared. PVAm-b-PVPin was synthesized from poly(vinyl acetate)-b-PVPi (PVAcm-b-PVPin) diblock copolymer via selectively hydrolysis. In water, PVAm-b-PVPin formed spherical polymer micelles with a PVPi core and a PVA shell. The hydrodynamic radius, light scattering intensity, and aggregation number of PVAm-b-PVPin increased with increasing PVPi block length. In contrast, the critical micelle concentration was reduced because of stronger hydrophobic interactions.

    • Thu Thao Pham
    • Seito Aibara
    • Shin-ichi Yusa
    Original Article
  • This focus review summarized current adhesives that are capable of macroscopic adhesion in seawater. The design strategies and performance of these adhesives were reviewed based on their bonding methods. Some future research directions and perspectives for under-seawater adhesives were discussed.

    • Hailong Fan
    Focus Review
  • The conformational relaxation of ethylene-propylene-diene terpolymer (EPDM) chains at the interface with a model filler of quartz was examined by sum frequency generation (SFG) spectroscopy in conjunction with molecular dynamics (MD) simulations. We found that the glass transition temperature (Tg) of EPDM was higher at the interface than in the bulk. Also, the conformational relaxation beyond the Tg was significant for ethylene units, but not for propylene units. This information might be useful in controlling the local conformation and dynamics of polymer chains at the interface.

    • Kiminori Uchida
    • Kazuki Mita
    • Keiji Tanaka
    Original Article
  • Microstructure-free strong all-wooden nanocomposites (AWNC) was directly made from the weak raw wood (RW) of paulownia, in which microscale wood fibers and void structures were dismantled into a fully consolidated structure containing nanofibrils (as the reinforcing phase) and noncrystalline cellulose, lignin, and hemicelluloses (as the matrix phase). This direct conversion was carried out through simultaneous chemomechanical densification/downsizing in three steps, including (1) partial delignification, (2) partial dissolution with IL or oxidation with TEMPO and ammonium persulfate (APS), and (3) hot pressing with cyclic pressurizing-depressurizing conditions.

    • Elmira Kaffashsaei
    • Hossein Yousefi
    • Mehrab Madhoushi
    Original Article
  • Various in situ measurement techniques have been applied to investigate changes in the three-dimensional structures and the physical properties of polyimides (PIs) generated at high pressures using a custom-built optical cell (up to 4,000 atm) or a diamond anvil cell (up to 80,000 atm). Moreover, the structural changes in the PI chain repeating units and interchain distances induced by the ultrahigh pressures were observed with WAXD, and they were compared with optical absorption, fluorescent and phosphorescent emission spectra, infrared absorption spectra, and refractive indexes observed under the same conditions.

    • Shinji Ando
    Focus Review Open Access
  • Two types of polyimide nanofibers (PINFs) were prepared. PINF-I (lengths = 305 ± 152 nm and diameters = 12 ± 2 nm) was prepared via crystallization of PI dissolved in a concentrated sulfuric acid solution. Adding t-butanol to a PINF-I aqueous dispersion and subsequent freeze–drying produced PINF-II (diameters = 105 ± 99 nm) with PINF-I aggregated into a fibrous form. The PI crystalline unit cell parameters were orthorhombic, a = 1.21 nm, b = 0.88 nm, and c = 2.23 nm (molecular chain axis direction).

    • Shota Kumano
    • Tomoyasu Takaki
    • Tetsuya Uchida
    Note Open Access
  • The modification of cellulose nanocrystal film using glycidyl silane compounds was performed with a coating process. Control of the surface structure and functionalization by silylation was achieved. Postmodification using glycidyl groups in silane-modified cellulose nanocrystal was demonstrated.

    • Hiroyuki Taniyama
    • Koji Takagi
    Original Article
  • PVDF forms β- and γ-phases in the presence of alkylammonium salts. We investigated crystal polymorphism obtained by various crystallization processes using FT-IR in PVDF added with two different alkylammonium salts. The fractions of crystalline phase changed with crystallization processes and ionic salts, which is attributed to the different crystallization mechanisms depending on the strengths of the ion-dipole interactions between alkylammonium salts and PVDF chains.

    • Tatsuaki Miyashita
    • Hiromu Saito
  • The grazing incidence diffracted X-ray blinking was proposed to evaluate the molecular motions occurring at polymer surfaces by measuring X-ray diffraction patterns near the total reflection angle over small time periods. When the crystallized polymer poly{2-(perfluorooctyl)ethyl acrylate}(PC8FA) film was measured, the results of the decay constants, which are indexes of molecular motions, suggested that the PC8FA surface is mobile compared to the bulk.

    • Rena Inamasu
    • Hiroki Yamaguchi
    • Yuji C. Sasaki
    Rapid Communication Open Access
  • A PS/silica hybrid nanomatrix was formed by graft copolymerization of first styrene and then VTES onto NR particles in the latex stage. This hybrid nanomatrix structure was composed of nanosilica with a size of less than 100 nm and PS, which resulted in outstanding mechanical and viscoelastic properties. The superior properties of the hybrid nanomatrix were due to the synergetic effect of PS and nanosilica. The morphology and mechanical properties of the hybrid nanomatrix were maintained after acetone extraction, whereas they were distorted and reduced, respectively, after annealing

    • Thuong Thi Nghiem
    • Nurul Hayati Yusof
    • Seiichi Kawahara
    Note Open Access
  • Copolymers of [2-(acryloyloxy)ethyl]trimethylammonium chloride (AETAC) and acrylamide (AAm) (AETAC-co-AAm) are polyelectrolytes used as flocculants in wastewater purification. Diffusion-ordered dimensional NMR spectroscopy (DOSY) experiments for AETAC-co-AAm samples with Mw ranging from 1.9 to 3.9 million and a polyacrylamide sample with Mw of 1.3 million were carried out in pure D2O and in D2O containing 0.1 or 1 M NaCl using an inverse-geometry diffusion-probe system. Projections of the DOSY contour plots onto the diffusion coefficient (D) dimension gave distributions of D for the AETAC and AAm units in the samples. The D values at the maximum point of the distribution (Dp) agreed fairly well with those determined by dynamic light scattering.

    • Kazuya Watanabe
    • Hiroyuki Matsushita
    • Koichi Ute
    Original Article Open Access
  • We studied the effects of polymer encapsulation of 290-nm-sized Al2O3(Al)-coated titanium dioxide (Al-TiO2) particles on the reflectance and hiding power of an inkjet image printed on a polyethylene terephthalate film. Two different polymer shells with 20–30-nm thickness of a poly(methyl methacrylate) (PMMA) shell and a multilayered shell of PMMA and poly(styrene) (PSt) (PMMA/PSt) were prepared using seeded semicontinuous emulsion polymerizations. The brightness (L*) value of the prints from the PMMA- and PMMA/PSt-encapsulated Al-TiO2 inks increased compared to bare Al-TiO2.

    • Md. Kamrul Hasan
    • Kazushi Enomoto
    • Seigou Kawaguchi
    Original Article
  • Submicron-sized SiO2/Al2O3(Si/Al)-coated titanium dioxide (Si/Al-TiO2) particles were encapsulated through the emulsion copolymerization of methacrylates using a thermoresponsive polymerizable nonionic surfactant, NE-10. An optimized water-dispersion method was developed to disperse Si/Al-TiO2 dried powders using an ultrasonic homogenizer, a paint shaker, and a pot mill rotator in the presence of partially neutralized poly(isobutylene-alt-maleic acid). The encapsulation efficiency (Fen) was affected by the monomer and initiator types, NE-10, and sodium dodecyl sulfonate concentrations. Fen > 90% was achieved by a two-step semibatch emulsion copolymerization under optimized conditions.

    • Md. Kamrul Hasan
    • Kazushi Enomoto
    • Seigou Kawaguchi
    Original Article