Search

Liquid-liquid interfacial reactions between FeSO4 (aq.) and benzenehexathiol (BHT) in chloroform at room temperature and at 45 °C give bis(dithiolato)iron nanosheets 1-RT and 1-H, respectively. Nan...

Reversible multielectron-transfer materials are of considerable interest because of the potential impact to advance present electrochemical energy storage technology by boosting energy density. To date, a few oxide-based materials can reach an electron-transfer number per metal-cation (e

Morphological control of C60 fullerene using liquefied porphyrins (1 and 2) as the host matrices was explored. Slow evaporation of the solvent of the equimolar mixture of porphyrin and C60 in toluene afforded the porphyrin/C60 composite with a 3:1 molar ratio. The stoichiometric binding behaviors suggest that specific porphyrin-C60 interactions operate the formation of the porphyrin/C60 composites, as corroborated by spectroscopic and thermal properties, and glazing-incidence wide-angle X-ray diffraction. Under the bulk conditions, the conventional thermodynamic advantage of multiple binding cooperativity for molecular recognition is unlikely to explain the stoichiometric binding behaviors. Instead, we propose a size-matching effect on the porphyrin-C60 interaction in the bulk porphyrin matrices, i.e., "supramolecular solvation". The glassy nature of the porphyrin matrices was transmitted to C60 through the specific interaction, and the porphyrin/C60 composites adopted glassy states at room temperature.

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.

Funder: White Rock Foundation, Funder: Jardine Foundation, Funder: Cambridge Commonwealth European and International Trust, Coordination nanosheets are an emerging class of 2D, bottom-up materials having fully π-conjugated, planar, graphite-like structures with high electrical conductivities. Since their discovery, great effort has been devoted to expand the variety of coordination nanosheets; however, in most cases, their low crystallinity in thick films hampers practical device applications. In this study, mixtures of nickel and copper ions are employed to fabricate benzenehexathiolato (BHT)-based coordination nanosheet films, and serendipitously, it is found that this heterometallicity preferentially forms a structural phase with improved film crystallinity. Spectroscopic and scattering measurements provide evidence for a bilayer structure with in-plane periodic arrangement of copper and nickel ions with the NiCu2 BHT formula. Compared with homometallic films, heterometallic films exhibit more crystalline microstructures with larger and more oriented grains, achieving higher electrical conductivities reaching metallic behaviors. Low dependency of Seebeck coefficient on the mixing ratio of nickel and copper ions supports that the large variation in the conductivity data is not caused by change in the intrinsic properties of the films. The findings open new pathways to improve crystallinity and to tune functional properties of 2D coordination nanosheets.

As an emerging additive manufacturing (AM) technique, melt electrospinning writing (MEW) is used to fabricate three-dimensional (3D) submicron filament-based scaffolds with adjustable pore size and customized structure for bone regeneration. Poly(L-lactic acid) (PLLA) scaffold with excellent biodegradability and biocompatibility is first successfully manufactured using our self-assembled MEW device. However, the ultralow cell affinity and poor bioactivity severely hamper their practical applications in bone tissue engineering. These issues are caused by the severe inherent biologically inert, hydrophobicity as well as the smooth surface of the MEW PLLA filaments. In this study, a green and robust alkaline method is applied to modify the scaffold surface and to improve the bioactivity of the MEW PLLA scaffold. Without deterioration in mechanical property but robust surface hydrophilicity, the optimal MEW PLLA scaffold shows promoted surface roughness, enhanced filament tensile modulus (~ 2 folds of the as-prepared sample), and boosted crystallizability (ultrahigh WAXD intensity). Moreover, after being cultured with KUSA-A1 cells, the 0.5 M NaOH, 2 h treated MEW PLLA scaffold exhibits higher osteoinductive ability and increased immature bone tissue amounts (3 times of controlled scaffold). Thus, the flexible surface functionalization by the specific alkaline treatment was found to be an effective method for the preparation of bioactivated MEW PLLA scaffolds with promoted bone regeneration.

Living organisms are typically composed of various tissues with microscopic cell-scale stiffness-heterogeneity, in which some cells receive dynamically fluctuating mechanical stimuli from the heterogeneous extracellular milieu during long-term movement. Although intracellular stress dynamics (ISD), which are closely related to the regulation of cell functions such as proliferation and differentiation, can be characteristically modulated in cells migrating on a matrix with stiffness-heterogeneity, it has been unclear how the mode of fluctuation of ISD affects cell functions. In the present study, we demonstrate that mesenchymal stem cells (MSCs) dual-durotaxing (i.e., both forward and reverse durotaxis) on microelastically-patterned gels with stiff triangular domains markedly amplify the fluctuation of ISD, nuclear shape, and the spatial distribution of chromatins, which makes the cells remain far from tensional equilibrium. We provide evidence that amplified chromatin fluctuation in the dual-durotaxing MSCs can cause activation of cellular vigor and maintenance of the stemness.

We report here spontaneous dewetting of a spin-coated, ultra-thin film of a sphere-forming block copolymer (BCP) upon thermal annealing, and that the dewetting resulted in the formation of plateau-shaped islands with a constant thickness consistent with the thickness of a monolayer, in which the spherical microdomains are regularly ordered two-dimensionally in a deformed hexagonal lattice. Thus, the spontaneous dewetting was ascribed to a mismatch between the initial spin-coated film thickness with respect to the monolayer thickness. Such dewetting of sphere-forming BCPs is considered to be deterministic compared to the cases of lamella- and cylinder-forming BCPs, as incommensuration in thickness is avoided by attaining perpendicular orientation without dewetting. We further quantitatively examined the ordering regularity of spherical microdomains in the dewetted monolayer islands to clarify the effect of confinement on sphere ordering. The degree of deformation of the hexagonal lattice was found to have an increasing tendency as a function of the degree of the deformation of the dewetted islands (the island shape), irrespective of the size of the island. Namely, islands with almost round shapes exhibit a well-ordered arrangement of the spherical microdomains in a perfect hexagonal lattice. Another notable finding is that the regular ordering of the spherical microdomains was found to be spoiled in the vicinity of the edge of the island. In other words, the spherical microdomains were well-ordered in a hexagonal lattice far from the edge of the island, while they were not regularly ordered in the vicinity of the edge, which may be due to mismatch between the curvature of the island's perimeter and the polygonal shape of ordered sphere grains.

Spider silk features extraordinary toughness in combination with great biocompatibility and biodegradability, fascinating researchers to prepare artificial silk fibers inspired from the natural art of spinning. In addition to C- and N-terminal domain, a repeat unit from Lactrodectus mactans spider eggcase silks displays substantial sequence conservation across species. Herein, we attempt to spin the engineered tubuliform spidroin 1 (eTuSp1) by microfluidics in a mode of modular assembly comprising the genetic construction, micellar formation, phase separation, and further solidification. Based on the conserved gene sequence, a unique amphiphilic behavior was predicted and then verified by combined techniques of dynamic light scattering, transmission electron microscopy, and synchrotron radiation X-ray diffraction to reveal the formation of micelle-like structure. Through the employ of biomimetic microfluidic devices, desolvation of eTuSp1 was simplified by the nonsolvent induced phase separation in place ...

Morphological control of C

Bis(diimino)metal coordination frameworks (MDI, M = transition metal), which are a class of metal organic frameworks with two-dimensional anisotropy, high electric conductivity, and redox activity, are attractive platforms for tailoring electrochemical properties by introducing a heterometallic composition. In this study, we synthesized heterometallic Co

Platinadithiolene nanosheet synthesized by interfacial transmetallation is a possible candidate of a 2D topological insulator at room temperature and an effective catalyst for the electrochemical HER., The construction of two-dimensional metal complex materials is fascinating because of the structural and functional diversity of these materials. Previously, we have reported the synthesis of electroconductive nickelladithiolene (NiDT) and palladadithiolene (PdDT) nanosheets using benzenehexathiol (BHT). Down the group from Ni, Pd to Pt, there is a distinct positive shift in the reduction potential; as a result, it becomes synthetically more challenging to stabilize Pt2+ than to form metallic Pt(0) in the presence of BHT as a reducing agent. Herein, a novel synthetic strategy for the preparation of platinadithiolene nanosheet (PtDT) using a dibutyltin-protected BHT ligand is reported, leading to transmetallation in the presence of dioxygen. Both free-standing stacked sheets and atomic layer sheets were obtained and characterized by microscopic techniques such as AFM, SEM, and TEM. To study the morphology of the sheets and determine their charge neutrality, X-ray photoelectron (XP) and infrared (IR) spectroscopic techniques were used. Powder X-ray diffraction analysis of the multilayer PtDT indicates a half-way slipped hexagonal configuration in the P3[combining macron]1m space group. The band structure of this PtDT exhibits a band gap at the Fermi level, which is different from that of NiDT in the staggered configuration, and a Dirac gap, indicating the possibility of 2D topological insulation at room temperature. PtDT is insulating but chemically activated by oxidation with I2 to increase the conductivity by more than 106 folds up to 0.39 S cm–1. The MDT sheets exhibit electrocatalytic activity for the hydrogen evolution reaction, and the activity order is NiDT < PdDT < PtDT.

It has been found that a special type of diluent can act as an agent to improve the crystallizability of poly(L-lactide) (PLLA). To present clear experimental results to support such an ability, we used time-resolved small and wide-angle X-ray scattering (SWAXS) to follow the isothermal crystallization of PLLA. The WAXS results show the enhancing effects of the diluent on the crystallization of PLLA, such as the reduction of the induction period and the acceleration of crystallization. Furthermore, the transformation from the δ phase to the α phase was also detected in the presence of the diluent. The growth of the crystalline lamellae in their thickness direction was accelerated in the presence of the diluent. It was further found that the diluent can accelerate the space filling of the stacks of crystalline lamellae in the specimen. The clear experimental results are revealed to confirm that a special type of a diluent can act as an agent of improving the crystallizability of poly(L-lactide) (PLLA). We conducted time-resolved SWAXS to follow the isothermal crystallization of PLLA. The WAXS result shows enhancing effects of the diluent on the crystallization of PLLA such as reducing induction period and accelerating crystallization. The growth of the crystalline lamellae in their thickness direction and the space filling by the stacks of crystalline lamellae are found to be accelerated in the presence of the diluent.

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.

We investigated surface structures of three kinds of block copolymer (BCP) specimens forming hard spherical microdomains embedded in a soft matrix, by using atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and grazing-incidence small-angle X-ray scattering (GISAXS). The three BCP specimens consist of different chemical species such as SEBS (polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene) and MAM (polymethylmethacrylate-block-poly(n-butylacrylate)-block-polymethylmethacrylate). Two of them form spherical microdomains at the thermodynamically equilibrium state (i.e., after fully long time thermal annealing), while the other exhibits spherical microdomains as a frozen state of the non-equilibrium structure (i.e., at the as-cast state using a selective solvent for the solution casting method), which was automatically frozen in by the vitrification of the hard component; the state is far from equilibrium). Nevertheless, such three different BCP specimens (chemically different in the molecular structure and thermodynamically different in the state) showed a common feature of the surface structure, as the outermost surface was completely covered with the single component having a lower value of the surface free energy, as revealed by XPS measurements. This finding significantly indicates that the AFM observation, which implies a coexistence of both BCP components on the free surface, misleads the conclusion. Although such surface coverage is reasonable and well-known, it was further found that the block chains are confined in a thin layer of the outermost region of the specimen. It is striking to find that the block chains are forced to be deformed (compressed) in order to meet the thermodynamic requirement of the surface coverage.

The metallically conductive bis(diimino)nickel framework (NiDI), an emerging class of metal-organic framework (MOF) analogues consisting of two-dimensional (2D) coordination networks, was found to have an energy storage principle that uses both cation and anion insertion. This principle gives high energy led by a multielectron transfer reaction: Its specific capacity is one of the highest among MOF-based cathode materials in rechargeable energy storage devices, with stable cycling performance up to 300 cycles. This mechanism was studied by a wide spectrum of electrochemical techniques combined with density-functional calculations. This work shows that a rationally designed material system of conductive 2D coordination networks can be promising electrode materials for many types of energy devices.

Expanded π-systems with a narrow highest occupied molecular orbital–lowest unoccupied molecular orbital band gap encounter deactivation of excitons due to the “energy gap law” and undesired aggregation. This dilemma generally thwarts the near-infrared (NIR) luminescence of organic π-systems. A sophisticated cofacially stacked π-system is known to involve exponentially tailed disorder, which displays exceptionally red-shifted fluorescence even as only a marginal emission component. Enhancement of the tail-state fluorescence might be advantageous to achieve NIR photoluminescence with an expected collective light-harvesting antenna effect as follows: (i) efficient light-harvesting capacity due to intense electronic absorption, (ii) a long-distance exciton migration into the tail state based on a high spatial density of the chromophore site, and (iii) substantial transmission of NIR emission to circumvent the inner filter effect. Suppression of aggregation-induced quenching of fluorescence could realize collective light-harvesting antenna for NIR-luminescence materials. This study discloses an enhanced tail-state NIR fluorescence of a self-standing porphyrin film at 1138 nm with a moderate quantum efficiency based on a fully π-conjugated porphyrin that adopts an amorphous form, called “porphyrin glass”.

Bis(diimino)nickel (NiDI) nanosheet is prepared by two methods of oxidation-promoted interfacial coordination reactions of nickel(II) ions with hexaaminobenzene. The thickness of the large chemically formed NiDI nanosheet can be controlled from atomic layers to thousands of layers. The morphology of electrochemically formed NiDI-modified electrode achievable within a minute suggests longitudinal growth of nanosheets at the surface. Increasing capacity of the NiDI with its amount indicates NiDI as a promising energy storage material.

The grain size was evaluated by atomic force microscope observation for the thin film specimen of the polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene triblock copolymer in which the perpendicularly oriented polystyrene cylinders are existing, while that in the interior of the specimen was evaluated by the small-angle X-ray scattering measurements. Both results for the grain growth on the surface and in the interior of the sample exhibited power-law behavior with the same extent of the exponent (~0.45).

We report experimental results of time-resolved 2d-SAXS measurements for a polystyrene- block -poly(ethylene- co -butylene)- block -polystyrene (SEBS) triblock copolymer as-cast film, which was subjected to a planar flow gradually imposed in the heating process of the specimen at a ramp-up rate of 2 °C/min. Before heating, non-equilibrium spheres were formed in the specimen. At 144 °C, the spheres were found to completely transform into cylinders. Some extent of cylinder orientation (0.5 in orientation factor) was already achieved, even at that temperature the strain of the specimen was as low as 0.5. From this fact, the directional coalescence of non-equilibrium spheres along with the planar flow direction (FD) was implied. As temperature increased, it was found the progress of the cylinder orientation parallel to FD as well as the orientation of the ( 1 0 1 ¯ 0 ) planes of hexagonal lattice parallel to the substrate surface. The fraction of the peak-top intensities of the ( 1 1 2 ¯ 0 ) reflections, I ( 11 2 ¯ 0 ) / ( I ( 10 1 ¯ 0 ) + I ( 11 2 ¯ 0 ) ) , was evaluated to examine the change in the orientational state of hexagonal lattice during application of the planar flow. The fraction was found to moderately increase with strain. However, the fraction of the grains, in which the ( 1 0 1 ¯ 0 ) planes are parallel to the specimen surface, is as low as 0.07 even at the highest strain state.

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+.

We have found extremely low efficiency of the elastomeric properties for SEBS (polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene) triblock copolymers having short polystyrene (PS) block chains. Since the SEBS specimens form spherical PS microdomains embedded in the matrix of the rubbery poly(ethylene-co-butylene) (PEB) chains, they exhibit elastomeric properties (thermoplastic elastomer film). However, it was found that the stress was dramatically decreased with time when the specimens were stretched and fixed at strain of 4.0. Furthermore, they showed macroscopic fracture with very short-term duration (400 s to 2 h). To reveal the reason for such low efficiency, we conducted time-resolved two-dimensional small-angle X-ray scattering (2d-SAXS) measurements for the SEBS triblock copolymer films under stretched state at strain of 4.0. Upon stretching, the strain-induced deformation (not fracture) of glassy microdomains was observed. In addition, the deformation of glassy microdomains was found ...

A comprehensive study of supramolecular polymerization of ditopic zinc (2-pyridylethynyl)porphyrin dimer 1 in toluene and thin films was performed. A glass-forming porphyrin bearing 3,4,5-tri((S)-3,7-dimethyloctyloxy)phenyl groups, named “porphyrin glass”, was introduced with the 2-pyridylethynyl group as a supramolecular organizing unit; two zinc (2-pyridylethynyl)porphyrins were held together by self-complementary pyridyl-to-zinc coordination bonds to form a slipped-cofacial stack. Then, ditopic zinc (2-pyridylethynyl)porphyrin could be extended to a linear supramolecular polymer. The small binding constant limited the degree of supramolecular polymerization of 1 in toluene solution. In spin-cast film, on the other hand, 1 adopted a form of supramolecular polymer of porphyrin glass, which was effective enough to display a large bathochromic shift of the absorption bands exceeding the narrowest limit of the optical band gap extrapolated from the electronic structures in solution. The supramolecularly pol...

Poly (l-lactic acid) (PLLA) is one of the most frequently used biobased polyesters due to its favorable mechanical properties. However, some properties such as slow crystallization rate and low crystallinity restrict its commercial uses. In order to overcome these limitations, organic nanofillers are incorporated into the PLLA matrix. Herein, we report the use of silk nanocrystal (SNC) as a solid-state nucleation agent, which has been prepared in the laboratory from the wastes of the muga silk cocoon. PLLA/SNC composites with 1.0 wt% loadings of SNC have been prepared by solution casting with dichloromethane as a cast solvent. Isothermal crystallization kinetics at 110 °C has been studied by the differential scanning calorimetry (DSC) and small- and wide-angle X-ray scattering (SWAXS) upon quenching from melt (200 °C for 5 min). As a result, it is found that loading SNC with 1.0 wt% caused the reduction of the induction period, the acceleration of crystallization, the increase of the final value of the degree of crystallinity, and the acceleration of lamellar thickening. These experimental results can be explained by the fact that the regular folding of the polymer chains is attained by the loading of SNC.

The nucleating effect of silk fibroin nano-disc (SFN) on the crystallization behavior of poly(L-lactic acid) (PLLA) was investigated by simultaneous synchrotron small- and wide-angle X-ray scattering measurements. For the isothermal crystallization at 110 &deg, C from the melt, the induction period of the PLLA specimens containing 1% SFN was reduced compared to that of the neat specimens, indicating the acceleration of the nucleation of PLLA. The final degree of crystallinity was also increased, and the crystallization half-time was decreased, which indicates that the overall crystallization process was accelerated. Furthermore, the final value of the crystallite size (the lateral size of the crystalline lamella) was slightly lower for the specimens containing 1% SFN than that for the PLLA neat specimen, although the crystallites started growing much earlier. However, it was found that there was no effect of SFN on the growth rate of the crystallite size. The lamellar thickening process was also accelerated with a clear overshooting phenomenon with the inclusion of 1% SFN. As for the polymorphism, the &alpha, &rsquo, phase is dominant with about 96%, but a small amount of the &alpha, phase (4%) is found to exist. It was found that the SFN can also accelerate the formation of the minor &alpha, phase as well as the major &alpha, phase.

Quadrupolar interactions of porphyrin bearing two pentafluorophenylethynyl terminals (1) drove the formation of a successive one-dimensional staircase structure, i.e., J-aggregates, to yield millimeter-length needles with a single-crystalline character in methylcyclohexane solution. In contrast, π-stacked interactions of porphyrin bearing two nonfluorinated phenyl terminals (2) formed no aggregates in solution. A spin-cast film of 1 also showed bathochromic shift of the Soret and Q bands, indicating the formation of J-aggregates. The molecular arrangement of the J-aggregates was revealed by microbeam glazing-incidence wide-angle X-ray diffraction (GIWAXD), and was in good agreement with the optimized structure generated by density functional theory (DFT) calculations.

Thermoplastic elastomers are elastomeric materials which contain hard domains as physical cross-linking for rubbery chains. Therefore, the hard domains are required permanently rigid. Nevertheless, we have found experimentally deformation of the hard domains upon uniaxial stretching of the thermoplastic elastomer films. In this paper, we report experimental results of deformation of glassy spherical microdomains in elastomeric triblock copolymer films upon uniaxial stretching, as revealed by two-dimensional small-angle X-ray scattering (2d-SAXS) measurements. Actually, shifts of the peak position of the particle scattering toward lower and higher q-regions were detected for q directions parallel and perpendicular to the stretching direction (SD), respectively, where q stands for the scattering vector. By assuming that spheres simply deformed into prolate spheroids with its major axis parallel to SD, 1d-SAXS profiles measured at several strains were successfully reproduced with model calculation of the 1d-...

A metal-lustrous self-standing film, named "porphyrin foil", was formed from a glass-forming polymeric porphyrin. The amorphous glass nature of the porphyrin foil played a key role in spontaneously producing a smooth surface. Its sharp contrast in intense absorption and specular reflection of light at each wavelength provided a brilliant metallic lustre.

A π-conjugated coordination nanosheet comprising bis(aminothiolato)nickel (NiAT) moieties was synthesized by the reaction of Ni(acac)2 with 1,3,5-triaminobenzene-2,4,6-trithiol at liquid-liquid and gas-liquid interfaces. The sheet thickness could be controlled down to a single layer (0.6 nm). Selected area electron diffraction and grazing incidence X-ray diffraction analyses indicated the formation of a flat crystalline sheet with a kagome lattice stacked in a staggered alignment. NiAT was reversibly interconverted to a bis(iminothiolato)nickel (NiIT) nanosheet by the chemical 2H+-2e- reaction, which was accompanied by a drastic change in electrical conductivity from 3 × 10-6 to 1 × 10-1 S cm-1. This change in conductivity was explained by the difference in band structures between NiAT and NiIT. NiAT acted as an efficient electrocatalyst for the hydrogen evolution reaction, showing strong acid durability and an onset overpotential of -0.15 V.

The amorphous nature of a series of zinc-porphyrins bearing two 3,4,5-tri((S)-3,7-dimethyloctyloxy) phenyl groups at the meso-positions, named "porphyrin glass", were tolerant of pi-conjugation engineering in ethynylene-linked dimers. The butadiyne-linked dimeric porphyrin glass formed an intermolecular excimer, which exhibited bright and exceptionally long-lived, near-infrared (NIR) luminescence at approximately 970 nm in the solid state. Therefore, porphyrin glasses overcame a general bottleneck for NIR-luminescence, such as an undesired pi-stacked aggregation of a large porphyrin plane in addition to the energy gap law. The formation of amorphous molecular glasses from a series of meso-ethynylene-conjugated zinc-porphyrins, named "porphyrin glass", is described. The butadiyne-linked dimeric porphyrin glass formed an intermolecular excimer, which exhibited solid-state, near-infrared (NIR) luminescence at approximately 970 nm.

Significant progress in cylindrical microdomain orientation is reported for a polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene triblock copolymer (SEBS-16) as analyzed by two-dimensional small-angle X-ray scattering. For this purpose, the morphological transition from sphere to cylinder was utilized. By applying compressional flow to the SEBS-16 specimen undergoing a morphological transition at 210 °C, superior cylinder orientation was achieved compared with the results obtained by applying the compressional flow to a cylindrical phase. The flow-treated specimens were further subjected to subsequent thermal annealing at 210 °C. It was found that the cylinder orientation proceeded by the subsequent thermal annealing even for flow-treated specimens with less oriented cylinders. Furthermore, the fraction of grains in which the plane of the hexagonal lattice of cylinders is oriented parallel to the specimen surface increased due to the subsequent thermal annealing, even for the specimen with the best cylinder orientation. Significant progress in cylindrical microdomain orientation is reported for a polystyrene-block-poly(ethylene-co-butylene)-block-polystyrene triblock copolymer (SEBS-16) as analyzed by two-dimensional small-angle X-ray scattering. To achieve this goal, the morphological transition from sphere to cylinder was utilized. By applying compressional flow to the SEBS-16 specimen undergoing a morphological transition at 210 °C, superior cylinder orientation was achieved compared with the results obtained by applying compressional flow to the SEBS-16 specimen containing the cylindrical phase.

Graphdiyne (GDY) comprises an important class in functional covalent organic nanosheets based on carbon–carbon bond formation, and recent focus has collected in the expansion of its variations. Here we report on the synthesis of a GDY analogue, TP-GDY, which has triphenylene as the aromatic core. Our liquid/liquid interfacial synthesis for GDY (J. Am. Chem. Soc. 2017, 139, 3145) was modified for hexaethynyltriphenylene monomer to afford a TP-GDY film with a free-standing morphology, a smooth texture, a domain size of >1 mm, and a thickness of 220 nm. Resultant TP-GDY is characterized by series of microscopies, spectroscopies, and thermogravimetric and gas adsorption analyses.

Layer-by-layer films composed of redox-active ruthenium dimer and Zr(IV) ions were fabricated on an indium tin oxide electrode. The fabricating behavior was monitored by cyclic voltammetry and UV-vis absorption spectral measurements. The orientation of the film was also monitored by grazing-incidence small-angle and wide-angle X-ray scattering (GISAXS) measurements, and it has been clarified that this film has a crystalline structure. The peaks obtained by GISAXS were changed upon oxidation reaction, which indicates that a change in the orientation of the ruthenium dimer occurred in the film.

The effect of high pressure on the higher-order structures of poly(oxyethylene) (PEG) crystallites in poly(d,l-lactide)/poly(oxyethylene) (PDLLA/PEG) blends during melting and recrystallization was investigated by in situ small-angle X-ray scattering (SAXS) measurements. It was found that melting temperature (T m) increases at 50 MPa in accordance with the prediction by the Clausius–Clapeyron equation. However, T m at slightly pressurized state (5 MPa) surprisingly decreased, suggesting that the effect of pressure is not so straightforward. It may be due to an increase of the miscibility under higher pressure, causing the melting point depression. Meanwhile, an advantage of analyses of SAXS data enabled us to determine directly discrete distribution of lamellar thickness as a function of temperature under pressure. As a result, lamellar thickening was observed at 5 and 50 MPa as temperature approaches closer to the melting point, but the tendency of thickening was lesser as compared to that observed at ambient pressure.

Triblock copolymers consisting of poly(oxyethylene) (PEG), poly( d -lactide) (PDLA), and poly( l -lactide) (PLLA) were successfully prepared by the two-step ring-opening polymerization of d - and l -lactides via PEG-PDLA diblock copolymers. These triblock copolymers as well as the diblock copolymer PEG-PDLA and a mixture of enantiomeric diblock copolymers PEG-PDLA/PEG-PLLA were emulsified to make their aqueous micelle solutions. It was found out that the triblock copolymers and the diblock copolymer mixture can form sc crystals in the core to highly stabilize the core–shell particles. In particular, the micelle of a triblock copolymer having a short middle PDLA block gave the smallest particles covered with thin layer of PEG coronas, because the sc crystals had formed around the core–shell interface. These results suggested that the micelle particle morphology can be tuned by changing the core structure even at constant hydrophilic/hydrophobic balance of the block chains.

Epitaxial crystallization onto a directionally crystallizable organic solvent, 1,3,5-trichlorobenzene, was applied to polymer blends containing regioregular poly(3-hexylthiophene-2,5-diyl) (P3HT) a...

β-Sheet crystals play an important role in determining the stiffness, strength, and optical properties of silk and in the exhibition of silk-type-specific functions. It is important to elucidate the structural changes that occur during the stretching of silk fibres to understand the functions of different types of fibres. Herein, we elucidate the initial crystallisation behaviour of silk molecules during the stretching of three types of silk fibres using synchrotron radiation X-ray analysis. When spider dragline silk was stretched, it underwent crystallisation and the alignment of the β-sheet crystals became disordered initially but was later recovered. On the other hand, silkworm cocoon silk did not exhibit further crystallisation, whereas capture spiral silk was predominantly amorphous. Structural analyses showed that the crystallisation of silks following extension deformation has a critical effect on their mechanical and optical properties. These findings should aid the production of artificial silk fibres and facilitate the development of silk-inspired functional materials.

Synthetic two-dimensional polymers, or bottom-up nanosheets, are ultrathin polymeric frameworks with in-plane periodicity. They can be synthesized in a direct, bottom-up fashion using atomic, ionic, or molecular components. However, few are based on carbon-carbon bond formation, which means that there is a potential new field of investigation into these fundamentally important chemical bonds. Here, we describe the bottom-up synthesis of all-carbon, π-conjugated graphdiyne nanosheets. A liquid/liquid interfacial protocol involves layering a dichloromethane solution of hexaethynylbenzene on an aqueous layer containing a copper catalyst at room temperature. A multilayer graphdiyne (thickness, 24 nm; domain size,25 μm) emerges through a successive alkyne-alkyne homocoupling reaction at the interface. A gas/liquid interfacial synthesis is more successful. Sprinkling a very small amount of hexaethynylbenzene in a mixture of dichloromethane and toluene onto the surface of the aqueous phase at room temperature generated single-crystalline graphdiyne nanosheets, which feature regular hexagonal domains, a lower degree of oxygenation, and uniform thickness (3.0 nm) and lateral size (1.5 μm).

Three-dimensional structural analyses of huge spherulites of poly(oxyethylene) (PEG) using X-ray computerized tomography (CT) in blends of PEG and amorphous poly(d,l-lactic acid) are reported for the first time. Slit-shaped cracks that were straight or curved were clearly observed using X-ray CT. Furthermore, they appeared to form a set of spokes, presenting a signature of a huge spherulite. Several aspects that are representative of an axialite structure are presented, and they are in good agreement with the intuitively proposed structural model for axialite long ago, although the size scale is much larger in our study.

Both AB diblock and ABA triblock copolymers consisting of poly(L-lactide) (PLLA: A) and poly(ethylene glycol) (PEG: B) were deposited on a silicon surface on which poly(D-lactide) (PDLA) had been preimmobilized. The deposit of the diblock copolymer (PLLA-PEG) formed band structures similar to those observed when the same copolymer was directly deposited on the silicon surface. In contrast, the deposit of the triblock copolymer (PLLA-PEG-PLLA) formed many particulates scattering over the surface. When the PLLA-PEG deposit was subjected to water-soaking, the original band morphology was completely replaced by the particulate morphology that was identical to that of the PLLA-PEG-PLLA deposit. Their FT-IR analyses revealed that both copolymers had been bound through the stereocomplex (sc) formation between the preimmobilized PDLA chains and the PLLA blocks of the copolymers. Grazing-incidence small-angle X-ray scattering (GISAXS) also supported these surface morphologies. It was therefore evident that hydrophilic PEG chains can be immobilized on the PDLA-preimmobilized surface by the sc formation.