Contact-killing antibacterial materials are attracting attention owing to their ability for sustained antibacterial activity. However, contact-killing antibacterial polystyrene (PS) has not been extensively studied because its chemically stable structure impedes chemical modification. In this study, we developed an antibacterial PS sheet with a contact-killing surface using PS synthesized from 2,2'-azobis-[2-(1,3-dimethyl-4,5-dihydro-1H-imidazol-3-ium-2-yl)]propane triflate (ADIP) as a radical initiator with cationic moieties. The PS sheet synthesized with ADIP (ADIP-PS) exhibited antibacterial activity in contrast to PS synthesized with other azo radical initiators. Surface zeta-potential measurements revealed that only ADIP-PS had a cationic surface, which contributed to its contact-killing antibacterial activity. The ADIP-PS sheets also exhibited antibacterial activity after washing. In contrast, PS sheets containing silver, a typical leachable antibacterial agent, lost all antibacterial activity after the same washing treatment. The antibacterial ADIP-PS sheet demonstrated strong broad-spectrum activity against both Gram-positive and Gram-negative bacteria, including drug-resistant bacteria. Cytotoxicity tests using L929 cells showed that the ADIP-PS sheets were noncytotoxic. This contact-killing antibacterial PS synthesized with ADIP thus demonstrated good prospects as an easily producible antimicrobial material.

Dynamic nuclear polarization (DNP) is effective for controlling the neutron scattering length of protons and can be utilized for contrast variation in small-angle neutron scattering (SANS). Using the TEMPOL solution soaking method as electron spin doping, the DNP–SANS technique was applied to human hair fiber for the first time. For dry and D 2 O-swollen hair samples, a drastic change in the SANS profile was observed at high polarization conditions (| P H P N | ∼ 60%, where P H and P N are the proton and neutron spin polarization, respectively). The SANS profile as a function of the magnitude of the scattering vector, q , was composed of a low- q upturn, a middle- q oscillation and a high- q flat region. The low- q upturn was assumed to be a combination of two power-law functions, q −4 due to a large structure interface (Porod's law) and q −2 due to random coil. The middle- q oscillation was well reproduced by numerical calculation based on the structure model of intermediate filaments (IFs) as proposed by Er Rafik et al. [ Biophys. J. (2004), 86 , 3893–3904]: one pair of keratin coiled-coils is located at the center and surrounded by seven pairs of keratin coiled-coils located in a circle (called the `7 + 1' model), and a collection of IFs is arranged in a quasi-hexagonal manner. For the observed SANS profiles for different P H P N , the IF term contribution maintained a constant q -dependent profile, despite significant changes in intensity. This indicates that the macrofibril is composed of two domains (keratin coiled-coils and matrix). In addition, D 2 O swelling enhanced the IF term intensity and shifted the polarization-dependent local minimum to higher P H P N . This behavior was reproduced by contrast factor calculation based on the two-domain model. Scattering length densities of keratin coiled-coil and surrounding matrix domains were calculated by use of the known amino acid composition, considering the hydrogen–deuterium exchange reaction during soaking with D 2 O solution of TEMPOL. As a result, it was found that for keratin coiled-coil domains, about 40% of the peptide backbone amide NH protons were replaced with deuterons. This means that 68% of the α-helix domain is rigid, but the rest is flexible to allow dynamic dissociation of the hydrogen bond. Furthermore, the local mass density of each domain was precisely evaluated. The obtained data are expected to be a guide for further detailed investigation of keratin and keratin-associated protein distribution. This approach is expected to be applied to a wide variety of bio-derived materials, which are water absorbing in general.

A novel surfactant of N–dodecanoyl–N–(2-hydroxyethyl)–β–alanine (coded as C12–EtOH–βAla) was synthesized by modifying the methyl group of N–dodecanoyl–N–methyl–β–alanine (coded as C12–Me–βAla). Amino-acid-type surfactants (C12–EtOH–βAla and C12–Me–βAla) are more healthy and environmentally friendly compared to sodium dodecyl sulfate (SDS). To investigate the microstructures of these new surfactants, we employed a method of time-of-flight small-angle neutron scattering (TOF SANS) at a pulsed neutron source, Tokai Japan (J–PARC). The advances in TOF SANS enable simultaneous multiscale observations without changing the detector positions, which is usually necessary for SANS at the reactor or small-angle X-ray scattering. We performed in situ and real-time observations of microstructures of collapsing shampoo foam covering over a wide range of length scales from 100 to 0.1 nm. After starting an air pump, we obtained time-resolved SANS from smaller wave number, small-angle scattering attributed to (1) a single bimolecular layer with a disk shape, (2) micelles in a bimolecular layer, and (3) incoherent scattering due to the hydrogen atoms of surfactants. The micelle in the foam film was the same size as the micelle found in the solution before foaming. The film thickness (~27 nm) was stable for a long time (<3600 s), and we simultaneously found a Newton black film of 6 nm thickness at a long time limit (~1000 s). The incoherent scattering obtained with different contrasts using protonated and deuterated water was crucial to determining the water content in the foam film, which was about 10~5 wt%.

Mechanically tough poly(L-lactide) (PLLA)/N,N-dimethylacetamide (DMAc) gels by rapid quenching using liquid nitrogen (LN) were synthesized. PLLA/DMAc solution at 110 degrees C was cooled at room temperature (PLLA-RT), or quenched by LN before keeping at RT (PLLA-LN). PLLA-RT with the PLLA concentrations of 5, 8, and 11 wt% did not form gel, while PLLA-RT with 14 and 17 wt% could form brittle gel exhibiting coarse structures. In contrast, PLLA-LN could form stable gel regardless of the PLLA concentration. The storage modulus of the gel with the PLLA concentration of 17 wt% increased from 78.7 kPa (PLLA-RT) to 563.7 kPa (PLLA-LN) at the strain of 0.1%. From the structural analysis, PLLA-RT formed spherulites (100-200 mu m in diameter), whereas PLLA-LN formed relatively uniform network structures with continuous microporous skeletons without spherulites. The structural changes significantly contributed to the formation of stable, re-moldable, biodegradable, and biocompatible physical gels with ecofriendly and enhanced mechanical properties.

A solid poly(2-methoxyethyl acrylate) (PMEA)-based polyurethane (PU) has been synthesized through reversible addition-fragmentation chain transfer (RAFT) polymerization followed by polyaddition. PMEA with four hydroxyl-groups (PMEA-(OH)4) synthesized using RAFT reagents with 4 hydroxyl groups works as an effective prepolymer and crosslinker. The thermoset PMEA-based PU can be obtained by mixing PMEA-(OH)4 and diisocyanate without additional agents for the synthesis. The temperature-independent mechanical property of the thermoset PMEA-based PU due to the chemical crosslinking points is confirmed by dynamic mechanical analysis (DMA) at temperatures ranging from 25 degrees C to 110 degrees C. The mechanical property at room temperature is also evaluated by tensile testing: The Young's modulus of PMEA-based PU increased from 454 +/- 31 kPa to 574 +/- 54 kPa by decreasing Mn of the PMEA prepolymer from 14,000 to 7,600. It is concluded that our synthesized PMEAbased PU exhibits sufficiently elastomeric characteristics as compared with conventional crosslinked PMEA, which may be used as a durable and more stretchable biomedical material.

Crystalline polymers may show different deformation responses depending on size of crystalline phase with respect to that of specimen. In the previous report, experimental stress-strain curves are numerically reproduced by the molecular chain plasticity FE analysis using a unit cell with hexagonal crystalline phases. However, there are some problems that the shape of crystalline phase in the unit cell is not always 6-fold symmetrical in the actual two-dimensional cross section of PP and the effect of the shape heterogeneity of crystalline phases on deformation responses has not been clarified. In the present report, the authors change the shape of some crystalline phase in the unit cell from hexagon to square and attempt to conduct the molecular chain plasticity FE analysis for amorphous phase and crystal plasticity FE analysis for crystalline one. Furthermore, the effect of shape heterogeneity of crystalline phases on deformation responses is investigated by comparing the results for unit cells with different heterogeneity.

Thermoresponsive gelation of the nanocomposites consisting of poly(lactic acid-co-glycolic acid)-b-poly(ethylene glycol)-b-poly(lactic acid-co-glycolic acid) (PLGA-b-PEG-b-PLGA) triblock copolymers and LAPONITE (LAPONITE/PLGA-b-PEG-b-PLGA nanocomposites) is investigated by decreasing the molecular weights of PLGA as 1130, 900, and 470 g mol(-1). As for the pure triblock copolymers, it is confirmed by UV-vis and SANS that a micellar structure with a hydrophobic core is formed even in the case of PLGA-b-PEG-b-PLGA with the lowest PLGA molecular weight of 470 g mol(-1) (Triblock0.5k). As for the nanocomposites with LAPONITE, it is found that the gelation temperature (T-gel) becomes less dependent on the PLGA-b-PEG-b-PLGA concentration and more stable as the PLGA molecular weight decreases, and that T-gel of the nanocomposites almost linearly decreases as the LAPONITE concentration increases. Eventually, the nanocomposite with Triblock0.5k reaches T-gel between room temperature and physiological temperature. In addition, gradual degradation behavior is observed for the nanocomposite with Triblock0.5k. Considering the monomeric molecular weights of LA and GA at the LA/GA ratio of approximate to 2.0, it is concluded that the PLGA-b-PEG-b-PLGA with the lower PLGA molecular weight (i.e., Triblock0.5k) can be effectively used for thermoresponsive and degradable hydrogels targeting biomedical applications.

Crystalline polymers may have some size effects that show different deformation responses depending on size of crystalline phase with respect to that of specimen. In the previous report, the effect of difference in crystal size on deformation response is investigated conducting some tensile tests on a polypropylene specimen. However, there are some problems that the shape of crystalline phase in the unit cell is different from the shape of crystalline phase of PP observed in the experiment and the reason why the size of crystalline phase becomes larger as the cooling temperature is lower cannot be clarified. In the present report, the authors change the shape of crystalline phase in the unit cell and attempt to conduct the molecular chain plasticity FE by analysis applying the new unit cell. Furthermore, the reason for the size increase of crystalline phase at low cooling temperature is quantitatively explained on the basis of classic nucleation theory. In addition, it is indicated that experimental stress-strain curves are numerically reproduced.

Nanofabricated polymers are extremely useful due to their high functionalities caused by the inherent multiscale structures of the nanostructured polymers. Nanostructured polymers for biocoatings can be classified into zero-dimensional (0D) polymeric nanoparticles, 1D polymeric nanofibers, and 2D polymeric nanosheets. The nanostructured polymers with such different dimensions were most often fabricated by emulsion polymerization, electrospinning, and spin coating. To add a desirable and advanced functionality to the targeted nanostructured polymers, surface modifications of the polymers can be highly advantageous. The surface modifications such as plasma etching, plasma-induced cross-linking, plasma polymerization, and chemical vapor deposition can effectively modify the surface characteristics of the nanofabricated polymers, leading to the enhancement of the bulk physical properties of the polymers. In this chapter, the fabrication methods of such nanostructured polymers are reviewed. In addition, several successful cases of well-controlled surface conditions of polymers by plasma processing are introduced.

(2021), The dynamic nuclear polarization method in neutron diffraction can increase the detection sensitivity of hydrogen. It is expected that the scattering length of hydrogen becomes about 8 times larger at maximum and high S/N ratio data can be obtained even with hydrogenated samples, not deuterated ones [1]. In order to realize the method, some radical molecules as an unpaired electron should be introduced into the sample, and high magnetic field (several T) and very low temperature (about 1 K) should be applied. In the previous study, the polarization ratio of 22.3% was obtained with lysozyme protein polycrystal in TEMPOL (4 - Hydroxy - 2, 2, 6, 6 tetramethylpiperidine - 1 - oxyl) 50 mM with a normal-conducting magnet of 2.5 T under off-beam condition [2]. This time, to achieve a higher polarization rate and to obtain a diffraction image using a polarized neutron beam, a nuclear polarization experiment of protein polycrystal was conducted using a super-conducting 7 T magnet installed at BL20 in MLF in J-PARC [3]. Both lysozyme and TEMPOL were purchased from Merck. Lysozyme polycrystal was made from several 1.5 mL-solutions of 60 mg/mL lysozyme, 100 mM TEMPOL and 9 % (wt/vol) NaCl in 50 mM sodium acetate buffer of pH 4.5 by batch method. About 100 mg polycrystal was mixed with 30 % (wt/vol) glycerol, then it was sealed within a cell made from Teflon and quartz windows. Incident neutron was polarized to 93 % negatively. And sample was polarized at 1.2 K to 68 % positively, to 59 % negatively and to 0 % under equilibrium at 4.2K. The total

A thermoplastic solid poly(2-methoxyethyl acrylate)(PMEA)-based polyurethane(PU) with excellent thermo-mechanical properties and antithrombogenicity was obtained by increasing the molecular weight of PMEA-based PU to ∼80 k.

This paper reports a unique phase separation behavior, a simultaneous-crosslinking-driven phase separation in co-gelation (SPSiC) core-shell microgel that spontaneously forms from a homogeneous pre gel solution of multiple polymers. The SPSiC microgel, composed of an alginate shell and an N- isopropylacrylamide (NIPAM) core, were synthesized by a single fabrication step wherein a mixed pre-gel solution of sodium alginate and NIPAM monomer was ejected by centrifugation with photo polymerization and ion crosslinking instantaneously. Phase separation was modeled by varying the degree of polymerization and the size of the polymer chain. Moreover, an implantable, multi-functional drug delivery system combined with a transdermal glucose sensor was demonstrated with core-shell Janus SPSiC microgels. This work shows a macroscopic phase separation behavior, which occurs during the gelation process, and also provides a simple and unique methodology to create multifunctional bio-microprobes. (c) 2021 Elsevier Ltd. All rights reserved.

The thermoresponsive gelation behavior and the degradation behavior of the nanocomposites consisting of poly(ethylene glycol)-b-poly(lactic acid-co-glycolic acid) (PEG-b-PLGA) diblock copolymers and clay nanoparticles (laponite) (laponite/PEG-b-PLGA nanocomposites) were studied by changing the blend ratio of the PEG-b-PLGA diblock copolymers using different PLGA molecular weights of 800 g/mol and 1600 g/mol: PEG-b-PLGA (1000-800, Diblock0.8k) and PEG-b-PLGA (1000-1600, Diblock1.6k). It was found that each gelation temperature was in the temperature range between 25 degrees C and 37 degrees C, when the PEG-b-PLGA concentration and the laponite concentration were kept at 3-4 wt% and 1 wt%, respectively. The degradation rate at 37 degrees C was found to be effectively regulated by the Diblock1.6k/Diblock0.8k blend ratio (DR). In detail, after 15 days of the degradation experiments, the weight loss was decreased by similar to 14% when DR changed from DR-0/100 to DR-100/0. It was, therefore, confirmed that DR was the key parameter to control the degradation behavior of the laponite/blended PEG-b-PLGA nanocomposites. (C) 2021 Elsevier Ltd. All rights reserved.

This study aims to understand the fundamental mechanical relationship between polypropylene (PP)-gels and solid PPs without solvent through mechanical and thermal analyses, by which the mechanical similarities between molten PPs and PP gels were found, leading to the reliable estimate of the mechanical properties of semi-crystalline gels. The gelation of syndiotactic and isotactic polypropylenes (sPP and iPP) was found when PPs were dissolved in 1,2,3,4-tetrahydronaphthalene (tetralin). Interestingly, it was found that the storage modulus of sPP-gel became higher than that of iPP-gel at low PP concentration (<~40 wt%). The result was distinctly different from the result of neat solid PPs (without solvent), where the modulus of solid sPP is generally significantly lower than that of solid iPP. Such inversion behavior in the mechanical property of semi-crystalline gels had not been reported and discussed before. By further investigation of the storage moduli of neat sPP and iPP, it was found that the storage modulus of sPP became higher than that of iPP above the melting points of PP, which was similar to the behavior of the storage moduli observed in the diluted PP-gels. Such similarity between PP-gels and PP melts was also observed within iPP samples with different molecular weights.

Ibaraki university developed the novel neutron microscope on the instrument iMATERIA at MLF of J-PARC, which was originally a powder diffractometer, recently reinforced by detecting small-angle scattering. The method of dynamic nuclear polarization (DNP) for protons was combined with small angle neutron scattering (SANS)(DNP-SANS). In a long course of history of DNP, our activity is the world's first challenge to incorporate DNP-SANS for routine industry uses. This “neutron microscope" provides us multiple reciprocal space images by changing scattering lengths of proton, in turn by varying “contrast" of individual scattering components. Conventionally, for the contrast variation, chemical treatments are required to substitute protons with deuterons. The DNP approach is suitable for industry application (for example to observe tire rubbers), because we do not need highly-specialized deuterium substitution. In this article, we describe theoretical background of DNP including scattering functions and the experimental of 7T super-conductive magnet, NMR to evaluate proton spin polarization, and microwave to change polarization. The sample preparation to dope radicals into sample specimens are necessary. We review the studies on homopolymers of polystyrene and polyethylene, poly (styrene-b-isoprene) diblock copolymer, and vulcanized SBR rubber.

For the development of blood-contacting biomedical devices, preventing platelet adhesion and avoiding subsequent thrombosis through antithrombogenic surface are vitally important. Poly (2-methoxyethyl acrylate) (PMEA) is a synthetic viscous polymer with an excellent antithrombogenic property, which has already been used as an antithrombogenic coating for biomedical purposes. The PMEA coating, however, can be easily broken due to its liquid-like feature, since the glass transition temperature (Tg) of PMEA is at −25οC. Solidifying PMEA has, therefore, been desperately desired for the improvement of the stability of PMEA coating. Also, once solidified, PMEA could be utilized not only for coating but also for structural materials for medical devices, expanding the application range of PMEA. In this study, PMEA was first solidified by triblock copolymerization with poly (methyl methacrylate) (PMMA) to obtain thermoplastic elastomers with excellent antithrombogenicity. We synthesized PMMA-PMEA-PMMA triblock copolymers with different volume fractions of PMMA (fMMA) by atom transfer radical polymerization (ATRP). The synthesis and the chemical structures of the new triblock copolymers were characterized and confirmed by proton nuclear magnetic resonance (1H NMR) analyses and gel permeation chromatography (GPC). The synthesized elastomeric triblocks were then compression-molded at 180οC to obtain solid transparent films. The tensile property was measured and the drastic change from the soft-elastomer phase to the hard-plastic phase was clearly observed by varying fMMA. It was found that the new triblocks possessed significantly higher tensile strengths than the other solidified PMEA by the previous studies. The platelet adhesion test revealed that the number of adherent platelets on the triblocks with fMMA of 0.12 and 0.40 was almost the same as that on pure PMEA, indicating that the synthesized triblocks possessed excellent antithrombogenicity similar to liquid PMEA. Further investigation on hydrated water and microphase-separated structures eventually revealed that the new triblock copolymers with a sufficient amount of intermediate water or with microphase separation on the surface resulted in excellent antithrombogenicity.

Kuchijirosho is a lethal infectious disease of fugu Takifugu rubripes, and the causative pathogen has been predicted to be an RNA virus. Although the homogenate of kuchijirosho-affected brain is pathogenic to fugu, the suspected viral particles have not been found in the brain and the viral genome has not been isolated. We attempted to clone the cDNA of the kuchijirosho virus genome using the Rapid Determination System for Viral RNA Sequence method. Three cDNA segments of ca. 1,000 nt each, which could be parts of the viral genome, were obtained from total RNA extracted from the brains of fugu artificially infected with kuchijirosho. According to RT-qPCR, the brain had more of these three kuchijirosho-associated RNAs (KARs) than any other tissues. KARs in the brain were detected 1-2 days after injecting the homogenate of kuchijirosho-affected brain and KARs expression levels were increased rapidly until death. These results show that the detection of KARs can be sufficiently effective for the molecular diagnosis of kuchijirosho. Even if KARs are parts of the viral genome, it is unclear to which taxonomic family the kuchijirosho virus belongs, because the nucleotide sequences of KARs did not correspond to those of any other organisms including viruses.

A method of time-of-flight, small-angle neutron scattering (TOF-SANS) has been developed based on the iMATERIA powder diffractometer at BL20, of the Materials and Life Sciences Facility (MLF) at the high-intensity proton accelerator (J-PARC). A large-area detector for SANS, which is composed of triple-layered 3He tube detectors, has a hole at its center in order to release a direct beam behind and to detect ultra-small-angle scattering. As a result, the pulsed-neutron TOF method enables us to perform multiscale observations covering 0.003 < q (Å−1) < 40 (qmax/qmix = 1.3 × 104) and to determine the static structure factor S(q) and/or form factor P(q) under real-time and in-situ conditions. Our challenge, using unique sample accessories of a super-conducting magnet and polarized neutron, is dynamic nuclear polarization (DNP) for contrast variation, especially for industrial use. To reinforce conventional SANS measurements with powder materials, grazing-incidence small-angle neutron scattering (GISANS) or reflectivity is also available on the iMATERIA instrument.

An area detector with a central hole structure was built up for small-angle neutron scattering (SANS) on the iMATERIA instrument at Japan Proton Accelerator Research Complex (J-PARC). Linear position-sensitive detector tubes filled with 3He gas were arranged in three layers leaving a central hole. As a result of the calibration process, a SANS measurement with wide q-range from 0.007 Å−1 to 4.3 Å−1 was achieved in double-frame operation, supplying neutrons with wavelengths from 1 Å to 10 Å. As a merit of this central hole structure, neutron transmission can be measured simultaneously to reduce experimental time and effort. This is ideal for time-resolved studies, in which the sample transmission can be time-dependent, throughout the whole experiment. Additionally, the data storage system in ‘event mode’ format provides an excellent platform for such time-resolved experiments.