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Two biodegradable polyesters, poly(butylene succinate) (PBS) and poly(butylene succinate‐co‐adipate) (PBSA), were artificially aged in a UV irradiation test chamber, and their photodegradation behaviors investigated. The attenuated total reflection (ATR) infrared (IR) spectra of the initial and UV‐aged samples revealed conformational changes in the tetramethylene sequences of the photoaged PBS and PBSA. The one‐dimensional wide‐angle X‐ray scattering (WAXS) profiles showed that the (110) d‐spacing of the α‐form crystal progressively decreased during UV aging, suggesting that the crystalline polymer chains became arranged more closely along the fiber axis. Accordingly, we conclude that PBS and PBSA transform from their TGTGT to nearly TTTTT conformations upon photoaging. The observed WAXS, small‐angle X‐ray scattering, and IR spectral data suggest that photodegradation preferentially occurs in the amorphous phase of each polymer. The less crystallizable butylene adipate co‐unit enhances the degradability of PBSA, with prolonged photooxidation leading to partial degradation of the crystalline region of the copolymer. This finding is consistent with and may be linked to the higher biodegradability of PBSA compared to PBS. [ABSTRACT FROM AUTHOR]

Strain‐induced crystallization (SIC) in natural rubber (NR) near crack tips significantly enhances crack growth resistance, but understanding the interplay between local strain field and crystallization remains challenging due to confined and heterogeneous characteristics. Using micro‐scale digital image correlation (DIC) and scanning wide‐angle X‐ray diffraction (WAXD, with a narrow 10 µm square beam), this study maps local strain tensor properties and SIC in the vicinity of the crack tip and its peripheral zone (≈3 mm × 1 mm area). The analysis reveals a significant correlation between these properties. In the peripheral zone, there is a noticeable deviation of both the principal strain axis and the crystal orientation from the crack opening direction. These deviations are linearly correlated, which indicates that shear strain plays a significant role in determining the crystal orientation. Crucially, the maximum tensile component in the tensor of local principal strains predominantly dictates local crystallinity. This simplicity is attributed to the limited variation in types of deformation within the SIC region, with corresponding to deformations falling between planar and uniaxial stretching. These findings pave the way for predicting crystallinity distribution using solely strain field data, offering valuable insights into the role of SIC in enhancing the crack growth resistance of NR. [ABSTRACT FROM AUTHOR]

Heterostructures of two‐dimensional materials realise novel and enhanced physical phenomena, making them attractive research targets. Compared to inorganic materials, coordination nanosheets have virtually infinite combinations, leading to tunability of physical properties and are promising candidates for heterostructure fabrication. Although stacking of coordination materials into vertical heterostructures is widely reported, reports of lateral coordination material heterostructures are few. Here we show the successful fabrication of a seamless lateral heterojunction showing diode behaviour, by sequential and spatially limited immersion of a new metalladithiolene coordination nanosheet, Zn3BHT, into aqueous Cu(II) and Fe(II) solutions. Upon immersion, the Zn centres in insulating Zn3BHT are replaced by Cu or Fe ions, resulting in conductivity. The transmetallation is spatially confined, occurring only within the immersed area. We anticipate that our results will be a starting point towards exploring transmetallation of various two‐dimensional materials to produce lateral heterojunctions, by providing a new and facile synthetic route. [ABSTRACT FROM AUTHOR]

The helix‐sense inversions of poly(β‐phenethyl l‐aspartate) (2P) and diblock copolymers (2P‐3P), with 2P and poly(β‐phenylpropyl l‐aspartate) (3P) blocks, were studied in their solid states using synchrotron wide‐angle X‐ray diffraction and small‐angle X‐ray scattering. The characteristic parameters of the π‐helix structure of 2P were directly determined in situ after the helix transition at a high temperature. In the 2P‐3P block copolymers, the main chains of the 3P blocks initially convert from right‐ to left‐handed α‐helices, and then the 2P blocks convert irreversibly from right‐handed α‐helices to left‐handed π‐helices. The chemical structures of the side chains of poly(l‐aspartic acid ester)s significantly affect their helix transition behaviors. [ABSTRACT FROM AUTHOR]

The helix‐sense reversal of poly(β‐phenylpropyl l‐aspartate) (3PLA) in the solid state was studied by synchrotron wide‐angle X‐ray diffraction and small‐angle X‐ray scattering. The direct determination of the characteristic helical pitch before and after the transition revealed that the transition takes place reversibly between the two α‐helices having opposite screw‐sense during the heating and cooling cycle. While the hexagonal packing remains unaltered, the helix‐sense inversion causes discontinuous changes in the molecular arrangement and, by extension, the crystalline dimension. In this study, another transition was detected at a higher temperature from the left‐handed α‐helix to the π‐helix, the molecular chirality being unaffected. [ABSTRACT FROM AUTHOR]

Because acellular vascular xenografts induce an immunological reaction through macrophage infiltration, they are conventionally crosslinked with glutaraldehyde (GA). However, the GA crosslinking reaction inhibits not only the host immune reaction around the graft but also the graft's enzymatic degradability, which is one of the key characteristics of acellular grafts that allow them to be replaced by host tissue. In this study, we used an 8‐arm polyethylene glycol (PEG) to successfully suppress macrophage infiltration, without eliminating graft degradation. Decellularized ostrich carotid arteries were modified with GA or N‐hydroxysuccinimide‐activated 8‐arm PEG (8‐arm PEG‐NHS), which has a molecular weight of 17 kDa. To evaluate the enzymatic degradation in vitro, the graft was immersed in a collagenase solution for 12 hr. The 8‐arm PEG‐modified graft was degraded to the same extent as the unmodified graft, but the GA‐modified graft was not degraded. The graft was transplanted into rat subcutaneous tissue for up to 8 weeks. Although CD68‐positive cells accumulated in the unmodified graft, they did not infiltrate into either modified graft. However, the GA‐modified grafts calcified, but the 8‐arm PEG‐modified graft did not calcify after transplantation. These data suggested that 8‐arm PEG‐NHS is a promising modification agent for biodegradable vascular xenografts, to suppress acute macrophage infiltration only. [ABSTRACT FROM AUTHOR]

In an article published in Angewandte Chemie, Hiroshi Nishihara et al. present a new method for creating lateral heterojunctions in two-dimensional materials. These heterojunctions have rectifying properties and can be fabricated by immersing a coordination nanosheet made from zinc ions and benzenehexathiol into iron and copper salt solutions. This research has implications for utilizing the attractive properties of two-dimensional materials more effectively. The authors of the article include Choon Meng Tan, Naoya Fukui, Kenji Takada, Hiroaki Maeda, Ekaterina Selezneva, Cédric Bourgès, Hiroyasu Masunaga, Sono Sasaki, Kazuhito Tsukagoshi, Takao Mori, Henning Sirringhaus, and Hiroshi Nishihara. [Extracted from the article]

In an article published in Angewandte Chemie International Edition, Hiroshi Nishihara et al. present a new method for creating lateral heterojunctions in two-dimensional materials. These heterojunctions have rectifying properties and are formed by immersing a coordination nanosheet made from zinc ions and benzenehexathiol into iron and copper salt solutions. This research has implications for utilizing the attractive properties of two-dimensional materials more effectively. The authors of the article include Choon Meng Tan, Naoya Fukui, Kenji Takada, Hiroaki Maeda, Ekaterina Selezneva, Cédric Bourgès, Hiroyasu Masunaga, Sono Sasaki, Kazuhito Tsukagoshi, Takao Mori, Henning Sirringhaus, and Hiroshi Nishihara. [Extracted from the article]

Abstract: In this study, we estimated the chain nature of atactic and stereoregular poly(substituted methylene)s containing a phenylmethoxy side chain at each main‐chain backbone carbon atom using synchrotron X‐ray scattering to understand the topological and conformational properties of these rigid polymers. The atactic poly(substituted methylene) showed a linear chain nature. Contrastingly, the stereoregular poly(substituted methylene) exhibited a random coil structure. © 2018 Society of Chemical Industry [ABSTRACT FROM AUTHOR]

Abstract: The correlation between the transport properties and structural degrees of freedom of conducting polymers is a central concern in both practical applications and scientific research. In this study, the existence of mesoscopic 2D coherent charge transport in poly(3,4‐ethylenedioxythiophene):poly‐(styrenesulfonate) (PEDOT:PSS) film is demonstrated by performing structural investigations and high‐field magnetoconductance (MC) measurements in magnetic fields of up to 15 T. The researchers have succeeded in observing marked positive MCs reflecting 2D electronic states in a conventional drop‐cast film. This low‐dimensional feature is surprising, since PEDOT:PSS—a mixture of two different polymers—seems to be significantly different from crystalline 2D materials from the viewpoint of structural inhomogeneity, especially in popular drop‐cast thick films. The results of the structural experiments suggest that such 2D transport originates from the nanometer‐scale self‐assembled laminated structure, which is composed of PEDOT nanocrystals wrapped by insulating sheets consisting of amorphous PSSs. These results indicate that charge transport in the PEDOT:PSS film can be divided into two regimes: mesoscopic 2D coherent tunneling and macroscopic 3D hopping among 2D states. These findings elucidate the hieratical nature of charge transport in the PEDOT:PSS film, which can provide new insight into a recent engineering concern, i.e., the anisotropic conductance. [ABSTRACT FROM AUTHOR]

A liquid/liquid interfacial synthesis is employed, for the first time, to synthesize a covalent two-dimensional polymer nanosheet. Copper-catalyzed azide-alkyne cycloaddition (CuAAC) between a three-way terminal alkyne and azide at a water/dichloromethane interface generates a 1,2,3-triazole-linked nanosheet. The resultant nanosheet, with a flat and smooth texture, has a maximum domain size of 20 μm and minimum thickness of 5.3 nm. The starting monomers in the organic phase and the copper catalyst in the aqueous phase can only meet at the liquid/liquid interface as a two-dimensional reaction space; this allows them to form the two-dimensional polymer. The robust triazole linkage generated by irreversible covalent-bond formation allows the nanosheet to resist hydrolysis under both acidic and alkaline conditions, and to endure pyrolysis up to more than 300 °C. The coordination ability of the triazolyl group enables the nanosheet to act as a reservoir for metal ions, with an affinity order of Pd2+>Au3+>Cu2+. [ABSTRACT FROM AUTHOR]

We applied the microbeam two-dimensional small-angle X-ray scattering (2d- µSAXS) technique in order to characterize orientation of polystyrene (PS) microdomains as a function of the distance from the free surface of a sample sheet down to the surface facing to the substrate, for depth profiling for spontaneous perpendicular orientation of PS cylinders in the matrix of polyethylenebutylene (PEB) in a PS- b-PEB- b-PS triblock copolymer thick sheet as thick as ∼0.5 mm. It has been revealed that near the free surface the cylinders were randomly oriented down to ∼70 µm in depth. Although this might indicate that the surface effect, which preferentially dictates cylinders to be oriented parallel to the surface, can propagate for such a long distance, 70 µm is unusually huge as compared to the general knowledge of the surface effect propagating at most for 1 µm. Experimentally examining further, we finally conclude that the 2d- µSAXS depth profiling overestimates the surface effect. This unfavorable conclusion may be ascribed to surface roughness of the sample sheet subjected to the measurement, and in order to obtain a good result a big effort is required to prepare the surface as flat as possible. [ABSTRACT FROM AUTHOR]

Anomalous small-angle X-ray scattering (ASAXS) profiles of Zr80Pt20 ribbons have been measured at the Zr K absorption edge. By annealing the melt-spun ribbons at 800 K, well defined SAXS patterns from nanoquasicrystals were observed, although the compositions of the quasicrystals (QC) and the amorphous matrix have previously been reported to be the same. The SAXS intensities were found to show a small anomalous effect at the Zr K edge. Contrast analysis suggested that the origin of the small-angle scattering is a small compositional fluctuation coupled with a small density difference, which enhances SAXS intensity but reduces the anomalous effect. A constant ASAXS intensity ratio for QC microstructure suggests that the ratio of the composition difference to the density difference between QC and the amorphous matrix is almost constant for the ZrPt ribbons examined here. [ABSTRACT FROM AUTHOR]

The intrinsic scattering from eight window materials commonly used at synchrotron facilities has been evaluated in the range 0.07 < q < 4 nm−1 by the use of a vacuum camera. Poly(oxydiphenylene-pyromellitimide) film, a polyimide film widely used as a window material for vacuum chambers, gave rise to two peaks at q = 0.8 and 4 nm−1. Poly(ether-ether-ketone) gave no Bragg peaks, although the background scattering was relatively high over the entire q range. When natural mica, synthetic mica, quartz glass, beryllium, silicon nitride and silicon carbide were compared, synthetic mica showed the lowest scattering in the range 0.6 < q < 5 nm−1, indicating that it is the most suitable window material for this q range. [ABSTRACT FROM AUTHOR]

We have investigated lamellar stacking structure of melt-crystallized and annealed high-density polyethylene (HDPE) thin films, with a thickness of ca 400 nm prepared on silicon wafers, using synchrotron grazing-incidence small-angle and wide-angle X-ray scattering (GISWAXS) measurements at the BL40B2 beamline in SPring-8. In-situ measurements of GISWAXS were carried out for the films in a stepwise annealing process under vacuum. Scattering peaks relating to the long period, the average distance between stacked crystalline lamellae, were measured only in the in-plane direction near the Yoneda peak of the grazing-incidence small-angle X-ray scattering patterns. On the other hand, the orthorhombic (110) and (200) reflections of oriented HDPE crystals were measured in the out-of-plane direction of the grazing-incidence wide-angle X-ray scattering patterns. It was revealed that crystalline lamellae were stacked in a parallel direction to the film surface and the long period increased from ca 25 nm to ca 32 nm in a stepwise annealing process. Within a lamella, molecular chains were found to be packed regularly and the chain axis (the c axis) was relatively oriented parallel to the film surface. [ABSTRACT FROM AUTHOR]

Small-angle X-ray scattering (SAXS) from dual-surfactant aqueous solutions made from sodium lauryl ether sulfate and coconut fatty acid amido propyl betaine was systematically measured as a function of the net sodium cation concentration, [Na+]*, and the surfactant concentration, CD. The SAXS intensity [ I( q)] was normalized to CD and the resultant I( q)/ CD was extrapolated to CD = 0 to give a form factor P( q) for each [Na+]* [where q = 4πsin(θ/2)/λ is the magnitude of the scattering vector, λ is the wavelength and 2θ is the scattering angle]. The low- q behaviour of P( q) was consistent with long rigid cylinders. The middle- and high- q profiles fitted well with a core–shell cylinder model for all [Na+]*. The core and total radii ( Rc and Rs) did not depend on [Na+]* at all: Rc = 1.2 ± 0.05 and Rs = 3.1 ± 0.05 nm for [Na+]* = 0.42–1.5 mol l−1, indicating that the salt concentration changes did not induce any structural changes and re-assembling of the surfactants comprising the micelles. This fact is in contrast to the rheological behaviour where the relaxation mode strongly depends on [Na+]*. The structure factor [ S( q)] was obtained by dividing I( q)/ CD by P( q) for each CD and the mean distance ( dm) between the micelles was obtained from the first maximum of S( q) versus q plots. The dm value decreased with increasing CD and [Na+]*, which is in good agreement with the theoretical prediction and experimental results for charged wormlike micelle solutions. [ABSTRACT FROM AUTHOR]