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The ionomers distributed on carbon particles in the catalyst layer of polymer electrolyte fuel cells (PEFCs) govern electrical power via proton transport and oxygen permeation to active platinum. Thus, ionomer distribution is a key to PEFC performance. This distribution is characterized by ionomer adsorption and deposition onto carbon during the catalyst-ink coating process; however, the adsorbed and deposited ionomers cannot easily be distinguished in the catalyst layer. Therefore, we identified these two types of ionomers based on the positional correlation between the ionomer and carbon particles. The cross-correlation function for the catalyst layer was obtained by small-angle neutron scattering measurements with varying contrast. From fitting with a model for a fractal aggregate of polydisperse core-shell spheres, we determined the adsorbed-ionomer thickness on the carbon particle to be 51 A and the deposited-ionomer amount for the total ionomer to be 50%. Our technique for ionomer differentiation can be used to optimally design PEFC catalyst layers.

We investigated in detail the structures in the poly(vinyl alcohol) (PVA) adsorption layers on a Si substrate, which remained on the substrate after immersing the relatively thick 30-50 nm films in hot water, by neutron reflectometry under humid conditions. For the PVA with a degree of saponification exceeding 98 mol %, the adsorption layer exhibits a three-layered structure in the thickness direction. The bottom layer is considered to be the so-called inner adsorption layer that is not fully swollen with water vapor. This may be because the polymer chains in the inner adsorption layer are strongly constrained onto the substrate, which inhibits water vapor penetration. The polymer chains in this layer have many contact points to the substrate via the hydrogen bonding between the hydroxyl groups in the polymer chain and the silanol groups on the surface of the Si substrate and consequently exhibit extremely slow dynamics. Therefore, it is inferred that the bottom layer is fully amorphous. Furthermore, we consider the middle layer to be somewhat amorphous because parts of the molecular chains are pinned below the interface between the middle and bottom layers. The molecular chains in the top layer become more mobile and ordered, owing to the large distance from the strongly constrained bottom layer; therefore, they exhibit a much lower degree of swelling compared to the middle amorphous layer. Meanwhile, for the PVA with a much lower degree of saponification, the adsorption layer structure consists of the two-layers. The bottom layer forms the inner adsorption layer that moderately swells with water vapor because the polymer chains have few contact points to the substrate. The molecular chains in the middle layer, therefore, are somewhat crystallizable because of this weak constraint.

A fibrillar-shaped metastable smectic phase forms during orientation-induced crystallization of poly(ethylene terephthalate). We investigated the effects of dimensions and regularity of the smectic phase on the mechanical properties by high-precision X-ray measurements. The drawing stress dependence was 76-168 MPa and the spinning speed dependence of 250-2000 m/min. The proportion, persistence length, and thickness of the smectic phase achieved their maximum values at 0.3-0.4 ms after necking. At this time g(II) also reached a minimum value of 3.7%-4.3%. The persistence length increased linearly with the natural draw ratio of as-spun fibers at less than 1500 m/min. The maximum values of the proportion, persistence length, and thickness showed no dependence on the drawing stress; however, the proportion and persistence length increased more rapidly. The increase of d-spacing with drawing stress led to an apparent elastic modulus of approximately 40 GPa for the oriented molecular bundle., Article, POLYMER.164:163-173(2019)

We combined the deuterium labeling and neutron reflectivity techniques to determine the fine structure of the electric double layer structure in an imidazolium ionic liquid (IL). For this, a simple and large scale deuteration method for imidazolium ILs was developed, where the deuteration level can be systematically controlled.

Order–order transitions during spin-coating processes in symmetric and asymmetric poly(styrene-block-2-vinylpyridine) (PS-b-P2VP) were investigated by using grazing incidence small-angle X-ray scattering (GISAXS). When the composition was symmetric (e.g., the copolymer P2VP volume fraction, fP2VP, was 0.50), we found that loose-packed nanocylindrical structures formed after the transition from micelles to a body-centered cubic (BCC) lattice structure during evaporation. After the BCC (110) plane aligned perpendicular to the substrate, microdomains coalesced into a cylindrical structure. This coalescence was caused by the convection effect of the solvent, and vitrification of PS and P2VP further prohibited transitions from the cylindrical structure, although generally, the equilibrium morphology in the bulk state is lamellae. For an asymmetric composition with fP2VP = 0.70, lamellar structures formed perpendicular to the substrate. During evaporation, the micelles transformed to hexagonal close-packed (HCP...

We performed H2O and D2O double-contrast neutron reflectivity measurements on ∼25 nm thick Nafion thin films on hydrophilic and hydrophobic carbon in water and 80% relative humidity vapor to investigate the depth profile of the water and Nafion distribution. We found a dense Nafion layer at the air or water interface regardless of the carbon hydrophilicity. On the other hand, a water-rich Nafion dense layer was observed at the carbon interface only for hydrophilic carbon. The double-contrast measurements provided quantitative information about the depth profile but simultaneously indicated that the sum of the volume occupancies of water and Nafion in the film was less than unity. We assessed the problem based on two possibilities: voids in the film or "residual water", which cannot be exchanged or is difficult to exchange with water outside.

Fibril-sized structures, which exhibit a density fluctuation of several tens to hundreds of nanometers, are important because they influence many properties of fibers and films, particularly the strength and thermal shrinkage of synthetic fibers. We analyzed the formation of fibril-sized structures after necking using ultra-small-angle X-ray scattering (USAXS), which enables observation of the void and craze formations. Continuous laser-heated drawing and undulator synchrotron radiation were adopted to measure the structural development of poly(ethylene terephthalate) (PET) and poly(phenylene sulfide) (PPS) fibers. Both fibers showed a clear increase in the meridional streak intensity just after necking and an increase in the equatorial streak after necking. These increases were distinctive for PPS. Moreover, a layer-lined streak appeared after necking only for PET. The intensity of the meridional streak increased with an increase in the draw ratio, whereas the intensity of the layer-lined scattering decreased with an increase in the draw ratio., Article, POLYMER JOURNAL.51(2):211-219(2018)

Poly(3-methylbutene-1) (P3MB1) is a polyolefin with a high melting temperature Tm (≈ 305 °C). We investigated the structural evolution of P3MB1 during isothermal crystallization from the melt by synchrotron radiation X-ray scattering and polarizing optical microscopy. At crystallization temperatures (Tc) of 297 and 290 °C or shallow quench conditions (ΔT = Tm0-Tc = 26 and 33 °C), needle-like crystals comprising lamellae were formed and flowed during their growth in the molten portion. To clarify the origin of the wide temperature region of the needle-like crystals in P3MB1, we estimated the critical lamellar width λ*, which is a parameter characterizing the suppression of lamellar branching, of P3MB1 and polyethylene (PE). The λ* of P3MB1 was larger than that of PE at the same ΔT, owing to the low viscosity of P3MB1. However, the range of λ* in the temperature region of the needle-like crystals of P3MB1 was 0.41

Methylcellulose (MC) is one of the widely used bio-based polymers derived from cellulose. MC possesses an amphiphilic property, since it contains both the hydrophilic hydroxyl group and the hydrophobic methoxy group in its molecular structure. Due to the amphiphilicity, aqueous MC solution shows temperature-sensitive property i.e. the lower critical solution temperature (LCST) type of phase behavior. On the other hand, a special organic salt, sodium tetraphenylborate (NaBPh 4 ) also possesses an amphiphilic property, since it consists of hydrophilic cation Na + and hydrophobic anion BPh 4 − . Motivated by an interest in the combined effect of the dual amphiphilicity, here we studied the addition effects of NaBPh 4 on the cloud point of aqueous MC. When the additive amount of NaBPh 4 to aqueous MC was small, the cloud point was depressed with the amount of NaBPh 4 , namely the salting-out effect. However, when the additive amount of NaBPh 4 exceeded a certain value, the cloud point was elevated drastically with the amount of NaBPh 4 , namely the salting-in effect. We proposed a hypothesis that the switching from the salting-out to the salting-in is caused by concentration-specific binding of NaBPh 4 to MC; NaBPh 4 mostly dissociates into Na + and BPh 4 − acting as the salting-out salt when the concentration of NaBPh 4 is small, whereas the hydrophobic anions BPh 4 − are bound to the hydrophobic region of MC acting like a surfactant when the concentration of NaBPh 4 exceeds a critical value. The presence of such a concentration-specific binding of anions was confirmed by the electric conductivity measurements.

The effects of spinning conditions on fiber properties are not well explained by the fiber structures because the birefringence, crystallinity, and SAXS patterns are often similar. In this study, the effects on the fiber structure development of polyethylene terephthalate after necking was analyzed by simultaneous WAXD/SAXS measurements. An X-shaped SAXS pattern was observed for all fibers drawn at the minimum draw ratio. In contrast, by drawing under a drawing stress of 100 MPa, the strong diffraction of the smectic phase and an obviously larger long period less than 1 ms after necking were observed for fibers spun at 500-1500 m/min, while almost no smectic phase was observed for fibers spun at 2000 m/min. A higher crystallization rate and clear draw ratio dependence of crystallization rate were also observed for the fiber spun at 2000 m/min. The clear differences in structure development can explain their differences in tensile strength and thermal shrinkage. (C) 2017 Elsevier Ltd. All rights reserved., Article, POLYMER.116:367-377(2017)

Fiber properties are decided by its structure, and the structure are mainly formed in the fiber drawing process. In this study, the effects of the draw ratio on the fiber structure development of polyethylene terephthalate after continuous neck-drawing were investigated using simultaneous WAXD/SAXS measurements. Low-oriented amorphous as-spun fibers were drawn to a draw ratio of 3.0-4.5, at which the fiber can be stably neck drawn. WAXD and SAXS images were obtained up to 2.0 ms when the structure was mainly developed. The smectic (0010) diffraction intensity and long period increased with increasing draw ratio up to 4.2, and a larger (0010) diffraction d-spacing was observed at a draw ratio of 4.5. The results suggest that more fibrillar structures were formed with increasing draw ratio up to 4.2, and more constrained molecular bundles were formed at a draw ratio of 4.5. A larger amount of constrained fibrillar structures can bear a greater tensile force in tensile tests, therefore the drawn fibers have higher tensile strengths. (C) 2017 Elsevier Ltd. All rights reserved., Article, POLYMER.116:357-366(2017)

We investigated the swelling behaviors of poly(vinyl alcohol) (PVA) films deposited on Si wafers with water vapor, which is a good solvent for PVA for elucidating structural and dynamical heterogeneities in the film thickness direction. Using deuterated water vapor, structural and dynamical differences in the thickness direction can be detected easily as different degrees of swelling in the thickness direction by neutron reflectivity. Consequently, the PVA film with a degree of saponification exceeding 98 mol % exhibits a three-layered structure in the thickness direction. It is considered that an adsorption layer consisting of molecular chains that are strongly adsorbed onto the solid substrate is formed at the interface with the substrate, which is not swollen with water vapor compared with the bulk-like layer above it. The adsorption layer is considered to exhibit significantly slower dynamics than the bulk. Furthermore, a surface layer that swells excessively compared with the underneath bulk-like layer is found. This excess swelling of the surface layer may be related to a higher mobility of the molecular chains or lower crystallinity at the surface region compared to the underneath bulk-like layer. Meanwhile, for the PVA film with a much lower degree of saponification, a thin layer with a slightly lower degree of swelling than the bulk-like layer above it can be detected at the interface between the film and substrate only under a high humidity condition. This layer is considered to be the adsorption layer composed of molecular chains loosely adsorbed onto the Si substrate.

Muon spin relaxation (μSR) measurements were performed to investigate the dynamics of polybutadiene (PB) reinforced by zinc diacrylate (ZDA). The spin relaxation rate was found to be almost independent of temperature below the glass transition temperature T g , while it increased monotonically with temperature above T g . In addition, the spin relaxation rate for PB including 14 vol% ZDA, which has a higher elastic modulus, was slower than that of PB without ZDA. Thus, μSR can clearly distinguish the dynamics of PB in these two samples, with the spin relaxations mainly caused by the so-called α-process (above T g ) and fast β-process (below T g ). To examine this scenario in detail, we performed μSR experiments as a function of longitudinal magnetic field (LF). The motional relaxation rate for PB was independent of temperature below T g , confirming that the spin relaxation is mainly induced by the fast β-process. The α-process above T g was also confirmed based on the Vogel–Fulcher-type temperature dependence, and the motional relaxation rate in the α-process was decreased by ZDA aggregates. These findings clearly show that μSR measurements provide useful information on the dynamics in complex polymer systems.

Aqueous methylcellulose (MC) forms hydrogel upon heating and the gel dissolves upon cooling i.e. thermo-reversible gelation. However, the values of the gelation temperature differ depending on the sources of MC samples and on the methods of determination as well. In this study, we have obtained a lower limit of the gelation temperature for a specific MC below which aqueous MC does not form the gel, by dually extrapolating the holding time for gelation to infinite and the mechanical probing force to zero. The gelation temperature obtained in this manner decreased with increasing concentration of the MC; to cite a case, it was located at ca. 21 ̊C for 10 wt%, which is ca. 10 ̊C lower than a conditional value estimated after holding 1 h without these dual extrapolations., 非公開申請承認(2019年12月18日図学支第37号)

The effect of draw ratio, molecular weight, and sea-island conjugated spinning with a polystyrene component on the fiber structure development of PET during laser drawing was analyzed by in-situ measurements with a 0.1ms time resolution using an ultra-high luminance X-ray beam generated from a synchrotron equipped with an undulator. The fiber temperature increased from 120°C to 160–220°C during the structure development process. By drawing the higher molecular weight PET to a higher draw ratio, a larger amount of fibrillar smectic mesophase formed just after the onset of necking, and a more highly oriented crystal formed after the extinction of the smectic mesophase. Accordingly, fibers with higher strength and higher thermal shrinkage stress were obtained. On the other hand, by conjugated spinning with a PS component, the fiber temperature increased along with an increase in the drawing stress, but the stress applied to the PET component should have decreased. The amount of smectic mesophase formed by the conjugated-spinning process was drastically decreased, and no crystallization induction time was observed, unlike the other cases. Crystallization, particularly the growth of a lamellar crystal, was also promoted. Moreover, a higher Young's modulus, a higher yield stress, and a higher shrinkage stress were observed for the conjugated-spun and drawn fibers. Therefore, the fibrillar smectic mesophase seems to block the formation of the lamellar crystal. Furthermore, the resultant fibrillar structure tends to result in a higher strength, but a relatively lower modulus and yield strength of the fiber., Article, POLYMER. 79:37-46 (2015)

Images of the spatial distribution of nanostructures in thin films were successfully reconstructed by grazing-incidence small-angle X-ray scattering (GISAXS) coupled with computed tomography (CT) measurements. As a model sample of inhomogeneous thin films, a thin film was patterned with four characters (F, B, S and L) consisting of nanoparticles of gold (Au), platinum (Pt), Au/Pt and Pt/Au, respectively, on a silicon substrate. The characters each produced respective two-dimensional GISAXS images which reflect the nanoparticle structures and their correlations in the thin film. The application of the GISAXS-CT technique to the characteristic scattering GISAXS intensity of each component enables one to reconstruct the images of each character independently. Moreover, it was found that the patterned images could be reconstructed even from very weak scattered intensities at higherqpositions and the diffuse intensities. These results indicate that the GISAXS-CT method is a powerful tool to obtain distinct reconstruction images detailing the particle size, shape and surface roughness.

The growth of hole-transporting nanostructures of regioregular poly(3-hexylthiophene) (P3HT) films with thermal annealing were examined by conductive atomic force microscopy (C-AFM). The C-AFM current images visualized spatially inhomogeneous hole transport in the film on a nanometer scale, with relatively low conductive regions and high conductive domains. The high conductive domains were attributed to the relatively high density regions of P3HT nanocrystallites in the film, which were determined during spin-coating. The current images obtained from the same area of the P3HT film showed that thermal annealing improved the hole-transporting property of the film on average, but both the size and spatial distributions of the relatively high conductive domains in the as-spun film remained almost the same even after annealing. Furthermore, we found that the increase in current flow proceeded mostly in the relatively high conductive domains. In these domains, the electrical connectivity among the crystalline phases was effectively improved by the growth of individual nanocrystallites, leading to the formation of preferred hole-transporting pathways in the direction of film thickness.

Summary The inhomogeneous structure of poly(styrene-ran-butadiene) (SBR) rubber crosslinked by sulfur has been investigated with the combination of Focusing small angle neutron scattering (Focusing SANS) and conventional small angle scattering (SANS) methods. A new inhomogeneous structure is found at smaller q-region in the SBR rubber in swollen state with Focusing SANS method, in addition to crosslinked network mesh and crosslinking inhomogeneity, which have already been found in chemical gels by several authors. The new inhomogeneous structure may be originated from the inhomogeneity of Sulfur or ZnO.

We have investigated the inner structure of shear-induced precursor of shish kebab of isotactic polystyrene (iPS) above the nominal melting temperature Tm using microbeam wide-angle X-ray scattering. We first studied the effects of the shear rate on the inner structure and found that the crystallinity in the precursor increased with the shear rate while the crystallite size was independent of that. This was explained in terms of effects of chain entanglements on shear-induced crystallization. We also studied effects of annealing below the nominal melting temperature Tm and found no changes in the crystallites size before and after the annealing, suggesting that the crystallites did not grow into shishs during the annealing below Tm although the kebabs grew.

The differential fast scanning calorimetry (DFSC) technique has been successfully applied to study the vitrification and crystallization of poly(butylene-2,6-naphthalate) (PBN). The cooling rate larger than 6000 K/s could make the PBN vitrify and the cooling rate larger than 30,000 K/s reduced effectively the development of the active nuclei. The critical cooling rate of 30,000 K/s is three times as large as that of the recently reported poly(ϵ-caprolactone) (PCL)'s. Namely, it turned out that PBN is a hard-to-vitrify polymer. The heating rate faster than 7000 K/s could prevent the cold crystallization from the proper glassy state. In the less severe cooling and heating rates than 30,000 K/s and 7000 K/s, respectively, a variety of structure formations, such as the nucleation, the mesophase formation, the crystallization and their multiple melting behaviors, have been observed.

We studied the dynamics of zinc diacrylate (ZDA) reinforced polybutadiene rubber (BR) (ZDA/BR) using the quasielastic neutron scattering technique to determine the effect of concentration of ZDA on polymer dynamics. First, we evaluated the temperature dependence of mean square displacements (〈u2〉) for ZDA/BR with different ZDA volume fractions. 〈u2〉 increased with temperature below 170 K, and we observed no significant ZDA volume fraction dependence. However, it increased more steeply above 170 K, and the value of 〈u2〉 was smaller for the samples with increasing ZDA fraction. To elucidate the origin of the decrease in 〈u2〉 with increasing ZDA content, dynamic scattering laws (S(Q,ω)) were analyzed. An increase in the elastic component, an increase in the mean relaxation time, and a broadening of distribution of relaxation time were observed with the increasing volume fraction of ZDA. In addition, the ZDA volume fraction dependence of the elastic component roughly corresponded to that of elastic modulus, indicating that the elastic component is related to its mechanical strength. Referring to the previously reported static structure of the present ZDA/BR system, a model for the heterogeneous BR dynamics was proposed. This model assumes the coexistence of immobile, mobile, and interfacial constrained mobile regions. It was found to be appropriate for the explanation of the observed dynamics. We proposed that a network-like structure of the BR having a high crosslinking density around ZDA aggregates is mainly responsible for the high elastic modulus of ZDA/BR.

In this study, we investigate the \ensuremath{\alpha} process of a polystyrene thin film using inelastic neutron scattering (INS), dielectric relaxation spectroscopy (DRS), and thermal expansion spectroscopy (TES). The DRS and TES measurements exhibited a decrease in glass transition temperature (${T}_{\mathrm{g}}$) with film thickness. On the other hand, an increase in ${T}_{\mathrm{g}}$ was observed in INS studies. In order to interpret this contradiction, we investigated the temperature dependence of the peak frequency (${f}_{\mathrm{m}}$) of the \ensuremath{\alpha} process probed by DRS and TES. The experiments revealed an increase in the peak frequency (${f}_{\mathrm{m}}$) with decreasing film thickness in the frequency region. This observation is consistent with the observed decrease in ${T}_{\mathrm{g}}$ with thickness. Interestingly, the increase in ${T}_{\mathrm{g}}$ with film thickness was confirmed by fitting the temperature dependence measurements of the peak frequency with the Vogel-Fulcher-Tammann equation, within the frequency region probed by INS. The discrepancy between INS and DRS or TES descriptions of the \ensuremath{\alpha} process is likely to be attributed to a decrease in the apparent activation energy with film thickness and reduced mobility, due to the impenetrable wall effect.

Using grazing-incidence small-angle scattering (GISAXS) with computed tomography (CT), we have individually reconstructed the spatial distribution of a thin gold (Au) layer buried under a thin poly(styrene-b-2-vinylpyridine) (PS-b-P2VP) layer. Owing to the difference between total reflection angles of Au and PS-b-P2VP, the scattering profiles for Au nanoparticles and self-assembled nanostructures of PS-b-P2VP could be independently obtained by changing the X-ray angle of incidence. Reconstruction of scattering profiles allows one to separately characterize spatial distributions in Au and PS-b-P2VP nanostructures.

We have studied kinetics of polymerization-induced phase separation of epoxy solution in oligoethylene glycol using light scattering and an optical microscope. It was found that special double droplet morphology was observed only in a very narrow range of epoxy fraction, which depended on the reaction temperature. In the narrow range the phase separation rate was very fast, and the bicontinuous structure which was typical in spinodal decomposition-type phase separation was observed only in the very early stage, suggesting that the solutions in the narrow fraction range entered directly the spinodal decomposition region without crossing the bimodal region. It is therefore considered that the temperature-dependent narrow fraction range corresponds to the trajectory of the critical point of the phase separation curve in the fraction–temperature diagram.

Soft materials, such as polymers and fibers, are key industries in Japan and play a significant role in our daily lives [1–3]. These materials also contribute to our modern society in a wide range of applications, such as in aircrafts and automobiles, and in a diverse variety of medical, electronic, and optical devices. In the future, it is expected that polymer science and technology will continue to expand and play an important role in research related to the environment [4], energy science [5], green technology [6], and biotechnology [7].

A novel UV lithographic technique for the patterning of the block copolymer (Pluronic) thin films is developed. The present method is based on UV-induced water affinity changes in block copolymer films. By water vapor post-treatment of the film, a difference in water content is established between UV illuminated and unilluminated sections, which can induce an osmotic pressure at the interface. This osmotic pressure drives the migration of Pluronic molecules, resulting in formation of patterns on the block copolymer films. Remarkably, this patterning method requires neither initiators nor polymerizable moieties which are essential for a conventional photolithographic approach. Additionally, the etching process is bypassed, eliminating the use of destructive acids or organic solvents and making this an environmentally friendly patterning protocol. It is reported that Pluronic is photo-responsive to UV exposure, which causes the dehydration of the PEO-PPO-PEO backbone.

To improve the mechanical and the thermal performance of poly(lactic acid) materials, this work focuses on the formation of stereo-complex crystals by blending poly(L-lactic acid) (PLLA) with poly(D-lactic acid) (PDLA). The resulting structure was analyzed using time-resolvedin situX-ray scattering, optical microscopy, differential scanning calorimetry and viscoelastic measurements. The objective of this study is to investigate the effect of shear flow imposed prior to crystallization on higher-order structure formation and acceleration of stereo-complex crystal growth of PLLA and PDLA blends using a wide spatial scale analysis and viscoelastic measurements. Density fluctuations of 100 nm scale were observed prior to nucleation byin situsimultaneous wide- and small-angle X-ray scattering measurements. These density fluctuations grew with time and the intensity increased with increasing shear rate. Furthermore, the results revealed that the PLLA and PDLA chains were only partially interpenetrated; consequently, stereo-complex crystals could grow only in the mixed PLLA/PDLA phase. The correlation length of density fluctuation prior to nucleation was strongly dependent on the mixed phases.

Local dynamics of polyacetylenes having polymethylated indan/tetrahydronaphthalene moieties have been studied using quasielastic neutron scattering, and the results obtained have been discussed together with former results with various poly(diphenylacetylene) derivatives. Clear quasielastic scattering was observed for the present polymers although they were in the glassy state, and the observed dynamic scattering laws were well fitted to a model function assuming the sum of narrow and broad Lorentzians. Both the relaxation rates and fractions from the narrow component exhibited a positive correlation with oxygen permeability coefficients ( P O 2 ) , while those from the broad component hardly related to P O 2 . Furthermore, the local flux, which is defined as the product of fraction and relaxation rate of the narrow component, is also found to be proportional to P O 2 . These findings imply that only the narrow component contributed to the gas permeability. Thus, it has been clarified that the local dynamics with a time scale of several tens of picoseconds plays a role of key importance for the gas permeability of substituted polyacetylenes in the glassy state.

Adhesamine is an organic small molecule that promotes adhesion and growth of cultured human cells by binding selectively to heparan sulfate on the cell surface. The present study combined chemical, physicochemical, and cell biological experiments, using adhesamine and its analogues, to examine the mechanism by which this dumbbell-shaped, non-peptidic molecule induces physiologically relevant cell adhesion. The results suggest that multiple adhesamine molecules cooperatively bind to heparan sulfate and induce its assembly, promoting clustering of heparan sulfate-bound syndecan-4 on the cell surface. A pilot study showed that adhesamine improved the viability and attachment of transplanted cells in mice. Further studies of adhesamine and other small molecules could lead to the design of assembly-inducing molecules for use in cell biology and cell therapy.

We studied the structure development in the dewetting process of deuterated polystyrene (dPS) and poly(vinyl methyl ether) (PVME) thin films, which were prepared by a spin-coating method on a quartz substrate, after the temperature jump into the two-phase region, using time-resolved specular and off-specular neutron reflectivity (NR), specular X-ray reflectivity (XR), light scattering (LS), and optical microscope (OM) measurements. The OM and specular XR measurements showed that there clearly existed an incubation period before dewetting. In the incubation period, composition fluctuations between dPS and PVME were developed due to phase separation. The specular NR results revealed that composition fluctuations began to occur just after the temperature jump along the depth direction over the film, giving rise to the composition gradient heterogeneously over the film. Composition fluctuations were also observed in the in-plane direction by the off-specular NR and LS measurements: the off-specular NR measure...

Preparation of strong fiber with ultrahigh strength and modus is a dream of polymer scientists and engineers. It is believed that a shish-kebab is the structure origin of the ultrahigh strength and modulus fiber. This article presents our investigation on the inner structure of shish-kebab precursor of isotactic polystyrene in μm scale formed by shear flow above the nominal melting temperature Tm using microbeam wide- and small-angle X-ray scattering (WAXS and SAXS). The microbeam WAXS experiments indicated that the precursor included crystallites with degree of crystallinity of ∼0.15%, which had higher melting temperature than normal lamellar crystals, meaning that its size (the length) was longer in the c-axis of crystals than the normal lamellar crystals. The microbeam SAXS experiments confirmed that approximately 1% of the crystallites in the precursor were rather long in the direction of c-axis. It is expected that such crystallites work as an initiator of a shish when it is below Tm.