Highly stretchable and self-healing polymer gels formed solely by physical entanglements of ultrahigh–molecular weight (UHMW) polymers were fabricated through a facile one-step process. Radical polymerization of vinyl monomers in ionic liquids under very low initiator concentration conditions produced UHMW polymers of more than 10 ⁶ g/mol with nearly 100% yield, resulting in the formation of physically entangled transparent polymer gels. The UHMW gels showed excellent properties, such as high stretchability, high ionic conductivity, and recyclability. Furthermore, the UHMW gel exhibited room temperature self-healing ability without any external stimuli. The tensile experiments and molecular dynamics simulations indicate that the nonequilibrium state of the fractured surfaces and microscopic interactions between the polymer chains and solvents play a vital role in the self-healing ability. This study provides a physical approach for fabricating stretchable and self-healing polymer gels based on UHMW polymers.

Mesoporous polymer microparticles are promising for energy, environmental, and biomedical applications. A linear polymer microparticle is desirable from the perspective of polymer recycling. In this study, mesoporous crystalline microparticles of a commercially available high-performance polymer, poly(ether sulfone) (PES), were prepared. Solvent-induced crystallization of PES in nitrobenzene resulted in nearly spherical microparticles with an average size of 5 μm and narrow size distribution. The microstructure and mesoporosity of the microparticles were characterized with scanning electron microscopy, X-ray diffraction, differential scanning calorimetry, and nitrogen adsorption/desorption, which gave a pore size distribution peaking at 7 nm with a porosity of 0.44. Fourier-transform infrared spectroscopy, Raman spectroscopy, and thermogravimetric analysis confirmed the cocrystal of PES and nitrobenzene. The formation mechanism of the PES microparticles was elucidated based on the theory of polymer spherulite formation. This study gives an insight on solvent-induced crystallization of rigid high-Tg polymers useful for the mesoporous polymer particle fabrication.

We successfully synthesized methylene blue (MB+)-immobilized hydroxyapatite (HM) nanoparticles by changing the initial P/Ca molar ratio. The immobilized amount of MB+ increased with increasing the initial P/Ca molar ratio from 0.6 to 4.0, and the HM had an elliptical shape (long length, 21-24 nm; short length, 11-13 nm) irrespective of the initial P/Ca molar ratio. Upon increasing the initial P/Ca molar ratio, the number of carbonate ions on the HM surface decreased, which would be owing to the electrostatic repulsion by the surface phosphate ions (i.e., P-O-), the surface P-OH mainly dissociated to form P-O-, and the electrostatic interaction of P-O- with MB+ enhanced. The bonding of MB+ with surface P-OH and Ca2+ sites of hydroxyapatite would be hydrogen-bonding and Lewis acid-base interactions, respectively. The optimum synthesis condition for MB+ immobilization at the monomer state was found to be the initial P/Ca molar ratio of 2.0. Here, the existence percentage of the MB+ monomer and the molecular occupancy of the surface carbonate ion at the initial P/Ca molar ratio of 2.0 were higher than those at 4.0 with no significant difference in the immobilized amount of MB+, indicating that MB+ at the initial P/Ca molar ratio of 4.0 is more aggregated than that at 2.0. These results suggested that a part of carbonate ions has a role as a spacer to suppress MB+ aggregation. Accordingly, the interfacial interactions between the MB+ monomer and the hydroxyapatite surface were clarified, which can effectively be controlled by the initial P/Ca molar ratio. These findings will provide fundamental and useful knowledge for the design of calcium phosphate-organic nanohybrids. We believe that these particles will be the base materials to realize diagnostic and/or therapeutic functions through the molecular state control by optimizing the synthesis conditions.

A pulsed dynamic light scattering (DLS) system, which would be potentially applied to nonlinear DLS with molecular selectivity, was developed by combining a sub-nanosecond pulsed laser with a software-based detection system. The distortion of the time correlation function due to the clipping effect in the photon counting module, and the resulting underestimation of the particle size, were successfully calibrated based on a theoretical simulation. The effective removal of random noises was also demonstrated via time gating synchronized to the laser pulses.

A polymer solution can be flash-frozen to prepare homopolymers with mesoporous structures in a template-free manner. The flash-freezing method is derived from the ice-templating or freeze-casting method. Herein, we comprehensively investigated the effects of 13 good solvents for polystyrene as well as the polystyrene concentration on the fabrication process. Solvents with high boiling-point-to-melting-point ratios yielded uniformly sized mesoporous polystyrenes at polymer concentrations ≥20 wt %. Such solvents provided a high specific surface area (328 m2/g) and a large mesopore volume (1.78 g/cm3) at the optimal polystyrene concentration. Solvents with medium-boiling-point-to-melting-point ratios formed bimodal mesopores, while a low polystyrene concentration gave hierarchical structures composed of mesopores and macropores. These results provide an understanding of the mechanism associated with the formation of mesopores and enable control over the desired mesopore morphology.

Control of the nanospaces of the hydroxyapatite nanoparticle films was successfully achieved using the citric acid coordination technique in a very simple way, which will provide a convenient bioceramic film preparation process.

As typical mechanical metamaterials with negative Poisson's ratios, auxetic metamaterials exhibit coun-terintuitive auxetic behaviors that are highly dependent on their geometric arrangements. The realization of the geometric arrangement required to achieve a negative Poisson's ratio relies considerably on the experience of designers and trial-and-error approaches. This report proposes an inverse design method for auxetic metamaterials using deep learning, in which a batch of auxetic metamaterials with a user-defined Poisson's ratio and Young's modulus can be generated by a conditional generative adversarial network without prior knowledge. The network was trained based on supervised learning using a large number of geometrical patterns generated by Voronoi tessellation. The performance of the network was demonstrated by verifying the mechanical properties of the generated patterns using finite element method simulations and uniaxial compression tests. The successful realization of user-desired properties can potentially accelerate the inverse design and development of mechanical metamaterials. (c) 2021 The Author(s). Published by Elsevier Ltd. This is an open access article under the CC BY license (http://creativecommons.org/licenses/by/4.0/).

Environmental crisis and water contamination have led to worldwide exploration for advanced technologies for wastewater treatment, and one of them is photocatalytic degradation. A one-dimensional hollow nanofiber with enhanced photocatalytic properties is considered a promising material to be applied in the field. Therefore, we synthesized titanium dioxide hollow nanofibers (THNF) with extended surface area, light-harvesting properties and an anatase-rutile heterojunction via a template synthesis method and followed by a calcination process. The effect of calcination temperature on the formation and properties of THNF were determined and the possible mechanism of THNF formation was proposed. THNF nanofibers produced at 600 °C consisted of a mixture of 24.2% anatase and 75.8% rutile, with a specific surface area of 81.2776 m2/g. The hollow nanofibers also outperformed the other catalysts in terms of photocatalytic degradation of MB dye, at 85.5%. The optimum catalyst loading, dye concentration, pH, and H2O2 concentration were determined at 0.75 g/L, 10 ppm, pH 11, and 10 mM, respectively. The highest degradation of methylene blue dye achieved was 95.2% after 4 h of UV irradiation.

Liquid marble (LM) is a droplet that is wrapped by hydrophobic solid particles, which behave as a non-wetting soft solid. Based on these properties, LM can be applied in fluidics and soft device applications. A wide variety of functional particles have been synthesized to form functional LMs. However, the formation of multifunctional LMs by integrating several types of functional particles is challenging. Here, a general strategy for the flexible patterning of functional particles on droplet surfaces in a patchwork-like design is reported. It is shown that LMs can switch their macroscopic behavior between a stable and active state on super-repellent surfaces in situ by jamming/unjamming the surface particles. Active LMs hydrostatically coalesce to form a self-sorted particle pattern on the droplet surface. With the support of LM handling robotics, on-demand cyclic activation–manipulation–coalescence–stabilization protocols by LMs with different sizes and particle types result in the reliable design of multi-faced LMs. Based on this concept, a single bi-functional LM is designed from two mono-functional LMs as an advanced droplet carrier.

© 2020 The Royal Society of Chemistry. Bottlebrush polymers (BPs) are highly tunable with regard to their glass transition temperature, refractive index, and shape. Herein, well-defined BPs were implemented as soft fillers to toughen multiphase plastics without loss of transparency and thermal stability, providing superior fracture toughness than a conventional linear polymer (LP). This study discloses a novel application of BPs and paves the way toward their further development. This journal is

© 2020, The Korean Institute of Chemical Engineers. A simple, promising, environmentally friendly, and high yield technique to synthesize high specific surface area (SSA) and porous graphene-like materials from glucose precursor through carbonization and controlled chemical iron chloride (FeCl3) activation was demonstrated. Designing this nanoporous graphene-based adsorbent with high SSA, abundant micropore volume, tunable pore size distribution, and high adsorption capacity, is crucial in order to deal with the demands of large-scale reversible natural gas storage applications. Raman spectroscopy, BET method of analysis, and N2 adsorption/desorption measurements at 196 °C were adopted to evaluate the structural and textural properties of the resultant glucose derived-graphene (gluGr) samples. The effects of different carbonization conditions, such as the inert environments (argon, helium, and argon) and temperatures (700, 800, 900, and 1,000 °C), have been studied. A glucose-derived graphene carbonized under nitrogen environment at 700 °C (NGr700) with highly interconnected network of micropores and mesopores and large SSA (767 m2/g) exhibited excellent methane (CH4) storage property with exceptionally high adsorption capacity, superior to other glucose-derived graphene (gluGr) samples. A maximum volumetric capacity up to 42.08 cm3/g was obtained from CH4 adsorption isotherm at 25 °C and 35 bar. Note that the adsorption performance of the CH4 is highly associated with the SSA and microporosity of the gluGr samples, especially NGr700 that was successfully synthesized by FeCl3 activation under N2 environment.

The present work focused on the determination of texture, morphology, crystallinity, and gas adsorption characteristics of porous graphene prepared from rice husks ashes at different stabilization temperature. The stabilization temperature applied in this work is 100 degrees C, 200 degrees C, 300 degrees C, and 400 degrees C to convert rice husk into rice husk ashes (RHA). Chemical activation was adopted at temperature 800 degrees C using potassium hydroxide (KOH) as dehydrating agent at (1:5) impregnation ratio to convert RHA into rice husk ashes-derived graphene (GRHA). The resultant GRHA were characterized in terms of their morphological changes, SSA, crystallinity, and functional group with TEM, the BET method, Raman spectroscopy, and XRD analysis, respectively. Results from this study showed that the SSA of the GRHA at stabilization temperature 200 degrees C (1556.3 m(2)/g) is the highest compared to the other stabilization temperature. Raman spectroscopy analysis revealed that all GRHA samples possess D, G, and 2D bands, which confirm the successful synthesis of the rice husks into porous graphene-like materials, known as GRHA. Appearance of diffraction peak in XRD at 44.7 degrees indicating the graphitic structure of all the GRHA samples. Meanwhile, the TEM images of GRHA200 exhibited wrinkled structures due to the intercalation of oxygen and a few layers of graphene flakes. These wrinkled structures and graphene layers are the other factors that lead to the highest SSA of GRHA200 compared to other prepared samples GRHA. Furthermore, the adsorption capacity of CH4 for GRHA200 is up to 43 cm(3)/g at 35 bar and ambient temperature, almost double the adsorption capacity performance of GRHA400 at the same operating pressure and temperature.

The development of thermally stable, highly transparent polymers with superior refractive indices and Abbe's numbers are important for the further development of next-generation technology such as miniaturized opto-integrated devices and advanced lenses. Highly transparent benzothiazole-based copolymers having either block or random sequences and high refractive indices were synthesized by reversible addition-fragmentation chain transfer (RAFT) polymerization. The conventional free-radical and RAFT copolymerizations of 2-benzothiazolyl vinyl sulfide (BTVS) and 2-vinylnaphthalene (VNA) produced random copolymers with adjustable BTVS contents between 8 and 54%. Chain extending the macrochain transfer agent, which was prepared by the RAFT polymerization of BTVS, with VNA was well-controlled, enabling the synthesis of block copolymers with high BTVS contents (up to 70%) and reasonable polymer yields (up to 60%). The benzothiazole-based homopolymer, poly(BTVS), exhibited a high refractive index (1.7432) and a reasonable Abbe's number (17.0). Excellent transmittances (>93%) of 400 nm light were observed for both copolymers composed of BTVS and VNA, and high refractive indices of 1.7178-1.6672 were achieved. The resulting benzothiazole-based copolymers exhibited high refractive indices (>1.7), high transparencies, tunable low glass-transition temperatures (T-g = 75-150 degrees C), and high thermal stabilities (T-d5 > 240 degrees C) by adjusting the chemical structure, composition, and sequence of the comonomer. This report presents development of the first high-refractive-index polymers derived from S-vinyl sulfide derivatives with benzothiazole side chains, exhibiting the synergistic effects of combining aromatic naphthalene and heteroaromatic benzothiazole units.

Porous (Ba,Sr)(Co,Fe)O3-delta (BSCF) ceramics with high open porosity and good electrical conductivity was fabricated using Ba0.5Sr0.5Co0.8Fe0.2O3-delta (BSCF), which shows a high mixed ionic-electronic conductivity. In general, during the fabrication of porous ceramics by the sacrificial template method using pore former particles, closed pores are easily formed unless sufficient pore former particles are added. In this study, we have devised a method using the gelatinization-retrogradation phenomena of starch for producing a porous body with an excellent percolated pore network structure. By dispersing BSCF and starch in an aqueous slurry (0-50% by weight) and heating, gelatinization of the starch occurred and the starch particles adhered to each other. Furthermore, in order to retain the percolated structure, the water solvent was removed by freeze-drying without heating to obtain a dried green body. The sintering behavior of the porous BSCF bodies prepared under various conditions was characterized by microstructural observations and relative density measurements. By optimizing the process conditions of the gelatinization and retrogradation, a porous body having an open porosity of 48.3%, and with 99% of the total pores open, was obtained. The matrix was also well connected and showed a sufficiently high conductivity which was similar to the porous bodies made by the traditional sacrificial template method.

Epoxy structural adhesives have been used extensively in the automotive and aerospace industries to bond assembly parts. Much effort has been devoted to enhancing the mechanical properties of epoxy resin by incorporating fillers. Among a variety of fillers investigated for this purpose, nanocelluloses are regarded as a promising type of emerging green filler material because of their excellent mechanical and physicochemical properties. Indeed, nanocelluloses have been used as a filler for polymer nanocomposites. However, the toughening and reinforcing effects of nanocelluloses on rigid epoxy adhesives have not yet been fully revealed, particularly from the perspective of adhesive bonded joints. Here we report that epoxy adhesive containing cellulose nanocrystal (CNC) aggregates produced using a solvent-free ball milling method achieves drastically improved adhesive strength and fracture toughness compared with that of the reference adhesive without CNCs. The epoxy adhesive containing CNC aggregates exhibited an excellent adhesive strength of 29 MPa and a fracture toughness of 389 J/m(2), which were 125% and 378% greater than those of epoxy adhesive without CNCs, respectively.

In this work, graphitic carbon nitride (GCN) photocatalyst-incorporated polyacrylonitrile (PAN) nanofibres (GCN/PAN nanofibres) were successfully prepared using electrospinning technique. The physicochemical properties of the fabricated GCN/PAN nanofibres were analysed using field emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM), elemental analyser, X-ray powder diffraction (XRD), Fourier transform infrared spectroscopy (FTIR) and UV-vis-NIR spectroscopy. The photocatalytic degradation by GCN/PAN nanofibres exhibited 90.2% photodegradation of partially hydrolysed polyacrylonitrile (HPAM) after 180 min under UV light irradiation in a suspension photocatalytic reactor. The results suggest that the photodegradation of HPAM contaminant by GCN/PAN nanofibres was due to the synergetic effects of HPAM adsorption by the PAN nanofibres and HPAM photodegradation by the GCN. This study provides an insight into the removal of HPAM from polymer-flooding produced water (PFPW) through photocatalytic degradation of liquid-permeable self-supporting nanofibre mats as a potentially promising material to be used in industrial applications. (C) 2019 Production and hosting by Elsevier B.V. on behalf of King Saud University.

Effective capture and in situ photodegradation of methylene blue (MB) dye is a promising technique to purify wastewater containing MB. With recently elicited ripples of discovery on graphitic carbon nitride (g-C3N4), this study investigates the performance of g-C3N4 on photodegradation of MB. In this study, polyacrylonitrile (PAN) nanofibres embedded with g-C3N4 photocatalyst was successfully prepared using electrospinning technique which produced liquid-permeable self-supporting photocatalytic nanofibre mats that can be handled easily. Different configurations of g-C3N4 were synthesised, bulk g-C3N4 (bg-C3N4) and nanosheets g-C3N4 (nsg-C3N4) from urea using a green facile template-free method. Effective photocatalytic activity of the g-C3N4 nanofibres was confirmed by 97.3% degradation of MB under visible light irradiation. Photodegradation of MB in aqueous solution by g-C3N4 nanofibres predominantly attributed to the synergetic effects of MB adsorption by PAN nanofibres and photocatalytic degradation of MB by g-C3N4 photocatalyst. This present work not only presents the simplest ecofriendly and economical approach to fabricate g-C3N4 nanofibre photocatalyst, but also paves new opportunities for this advanced photocatalyst as great potential in environmental remediation for treatment of industrial MB wastewater.

We successfully prepared hybrid nanoparticles (NPs) with photofunctional interfaces between the citric acid (Cit) molecules and europium(III) ion (Eu3+)-doped hydroxyapatite (HA) (Eu:HA) to provide bifunctional cell-labeling and cytostatic suppression. In particular, the Eu:HA NPs were synthesized in the presence of Cit, and the Cit molecules were hybridized with the Eu:HA NPs (Cit/Eu:HA). The physicochemical properties based on the interfacial Eu:HA-Cit interactions in the NPs were elucidated. The atomic structures on the Eu:HA NP surface layers were disordered by increasing the liquid-solid interfaces by the interactions between the Cit molecules and the Ca site of Eu:HA NPs. It was suggested that the Cit molecules that interacted with the Eu:HA NP surfaces sterically hindered the NP growth by the inorganic-organic interactions. Moreover, it was demonstrated that the interactions of Cit as an organic molecule and Eu:HA as an inorganic matrix were important for achieving the efficient photoluminescence properties. Thus, the efficient luminescence ability including the internal efficiency for cancer cell labeling was achieved, and simultaneously, the Cit molecular effect on the suppression of the cancer cell line growth was investigated. As a result, the luminescence enhancement with the hybridization was successfully elucidated. In particular, the low symmetry of the coordination structure for the Eu3+ ion at the Ca(I) site provided the enhanced luminescence efficiency. Furthermore, the folate N-hydroxysuccinimidyl ester (FA-NHS) was immobilized on the Cit/Eu:HA NPs to enhance the uptake efficiency of the NPs into the cancer cells. Then, the cytocompatibility and the cell-labeling property were evaluated to investigate the effect of the NPs on the cancer cell growth suppression by the Cit molecules. Cancer cell growth suppression was successfully achieved by the interactions with the Cit/Eu:HA NPs. Furthermore, the Cit/Eu:HA NPs reacted with the cells to exhibit red-color luminescence from the cells while suppressing cancer cell growth, indicating the bifunction of cell-labeling and cytostatic suppression in one particle. The hybridized Cit molecules could significantly contribute to the tumorized cell (sphere) growth suppression. In particular, the Cit/Eu:HA NPs were effectively reacted with the spheres after a culture time of 60 h, and the luminescent labeling with following the cellular shapes could be achieved 1 h after NP addition, indicating the rapid labeling process with cytostatic suppression for interacting with the spheres.

Machine learning is emerging as a powerful tool for the discovery of novel high-performance functional materials. However, experimental datasets in the polymer-science field are typically limited and they are expensive to build. Their size (< 100 samples) limits the development of chemical intuition from experimentalists, as it constrains the use of machine-learning algorithms for extracting relevant information. We tackle this issue to predict and optimize adhesive materials by combining laboratory experimental design, an active learning pipeline and Bayesian optimization. We start from an initial dataset of 32 adhesive samples that were prepared from various molecular-weight bisphenol A-based epoxy resins and polyetheramine curing agents, mixing ratios and curing temperatures, and our data-driven method allows us to propose an optimal preparation of an adhesive material with a very high adhesive joint strength measured at 35.8???1.1?MPa after three active learning cycles (five proposed preparations per cycle). A Gradient boosting machine learning model was used for the successive prediction of the adhesive joint strength in the active learning pipeline, and the model achieved a respectable accuracy with a coefficient of determination, root mean square error and mean absolute error of 0.85, 4.0?MPa and 3.0?MPa, respectively. This study demonstrates the important impact of active learning to accelerate the design and development of tailored highly functional materials from very small datasets.

Superhydrophobic materials with micro/nanotextured surface have attracted tremendous attention owing to their potential applications such as self-cleaning, antifouling, anti-icing, and corrosion prevention. Such a micro/nanotextured surface is a key for high water repellency. However, such a texture is fragile and readily damaged when the material is deformed, scratched, or sliced off. Thus, it is challenging to develop superhydrophobic materials that can sustain high water repellency after experiencing such a mechanical deformation and damage. Here we report abrasion/ scratching/slicing/droplet impacting/bending/twisting-tolerant superhydrophobic flexible materials with porcupinefish-like structure by using a composite of micrometer-scale tetrapod-shaped ZnO and poly(dimethylsiloxane). Owing to the geometry of the tetrapod and elasticity of poly(dimethylsiloxane), the composite material exhibits stable water repellency after 1000 abrasion and 1000 bending cycles, or even after their surfaces were sliced off many times. The material maintains superhydrophobicity even under a mechanically deformed state such as bending and twisting. The materials can be painted on a variety of substrates and molded into desired shapes and used in a myriad of applications that require superhydrophobicity.

Superhydrophobic materials that prevent unwanted liquid adhesion can easily lose this property because of limited mechanical durability despite topological/chemical control and/or robust material selection. Here, long-lasting superhydrophobic coatings with a system to effectively detect and repair damaged areas with "liquid marble," a droplet covered with hydrophobic nanoparticles, are reported. The particles prevent direct contact between the droplet and the substrate (Cassie state). However, they can adhere to the non-superhydrophobic damaged area in response to the substrate wettability via an external force or an increase in liquid volume via penetration of the outer nanoparticle layer (Wenzel state). This Cassie-Wenzel transition thus induces self-assembly of the nanoparticles onto the non-superhydrophobic area in response to the wettability, restoring superhydrophobicity.

Cost-effective purification technology of oilfield produced water (OPW) is becoming a global challenge for future petroleum exploration and production industry. Energy-efficient operation of membrane separation is potentially promising. However, severe fouling problem of oil droplets demands new robust and fouling-resistant membranes with high permeability and rejection efficiency. Here, we propose a photocatalytic nanofiber-coated inorganic hollow fiber membrane suitable for OPW treatment. The membrane was fabricated by coating polyacrylonitrile (PAN) nanofiber incorporated with graphitic carbon nitride (GCN) photocatalyst on an alumina (Al2O3) hollow fiber membrane. While the highly porous coating made of smooth hydrophilic nanofibers facilitated water permeation, the coating effectively captured oil droplets in its opening, resulting in a better rejection efficiency of oil contaminants. Its sparse mesh morphology prevented oil contaminants to form dense fouling film on the membrane surface and maintained high permeate flux even after 180 min filtration. The best permeate flux of 640 L.m(-2).h(-1) and oil rejection percentage of 99% were recorded for 180 min crossflow filtration of OPW at 2 bar along with the highest pure water flux of 816 L.m(-2).h(-1). The photocatalytic activity of GCN enabled the coating to degrade the captured oil contaminants under UV irradiation, demonstrating permeate flux of 577 L.m(-2).h(-1) and oil rejection of 97% after three cycles of 180 min filtration. The excellent fouling resistance and cleaning performances of the membrane are considerably beneficial for a long-term repeated filtration operation. This work will motivate researchers to develop nanofiber-coated hollow fiber membranes for future membrane separation technology.

Polyrotaxanes (PRs), a new class of supra-molecular polymers, have recently attracted considerable attention in materials science because of their unique structure and intriguing effects on material properties. Here, we report that a PR is capable of toughening a rigid epoxy adhesive without phase separation morphology, unlike the interface-mediated toughening mechanisms established in conventional epoxy resins. A PR bearing polycaprolactone graft chains on wheel-like molecules was dispersed homogeneously in an epoxy adhesive via intermolecular hydrogen bonding. The PR-incorporating epoxy adhesive exhibited simultaneous increase in adhesive strength, fracture displacement, and fracture toughness while retaining its high glass transition temperature and tensile modulus. Morphological, thermal, and mechanical characterizations suggested that the toughening mechanism originates from the PR supramolecular structure, allowing the wheel-like molecules to rotate around and slide along the polymer main chain. The study revealed the fracture behavior of PR-containing epoxy adhesives, which may be beneficial for practical applications of network polymers.

Resettable thermosetting adhesive systems have been explored with the help of a thermo-reversible Diels-Alder (DA) reaction between a furan-bearing random copolymer and bismaleimide as a dynamic bond cross-linkage. The obtained adhesive materials exhibited good lap shear strength in the cross-linked state of up to approximate to 8 MPa. In addition, the bonding/debonding state of the adhesives could be reset by an appropriate choice of thermal treatment.

The self-assembly of amphiphilic building blocks represents an elegant strategy to produce (nano)structures with unique functionalities and is often investigated for a wide range of applications in biology and materials science. Herein, we report micro- to nanoscale vesicular assembly made of naturally abundant dendritic polyphenols, tannic acid (TA). Rich content in several plant parts, nontoxicity, and the inherent ability of diverse molecular interactions including H-bonding, pi-pi interactions, and metal coordination make such polyphenols a promising class of natural building blocks for supra molecular assembly and precursors for natural surfactants. The facile modification of hydrophilic TA by introducing n-alkyl chains produced TA-based multiarm surfactants, which facilitates molecular assembly in water. Systematic manipulations of processing parameters including amphiphile concentration, cosolvent ratio, and mixing rate enabled us to achieve well-defined and size-tunable spherical vesicles in the range 0.1-1.0 mu m; these were enclosed by a molecularly thin periphery of ca. 3-5 nm. Further, both hydrophilic and hydrophobic guest molecules could be encapsulated noncovalently into the vesicle, implying the presence of hydrophilic interior and hydrophobic alkyl-chain-dominated periphery in such vesicular assembly. Next, controlled disassembly of such vesicles was thoroughly examined and demonstrated high potential as nanocarriers of guest molecules. Moreover, the presence of nonsubstituted aromatic hydroxyls due to partial modification of polyphenols offered radical scavenging or antioxidant properties of the vesicles. The present report heralds a new direction of utilizing chemically modified low-cost TA as diverse supramolecular tectons, nanocarriers, and functional natural additives in a wide range of practical applications.

This paper reports transmission and scattering spectra of poly (vinyl chloride) (PVC) in styrene liquid, which is derived from Christiansen effect. The spectra were measured by varying scattering angles. Further discussion on Christiansen color was provided in the paper entitled "Transmitting and scattering colors of porous particles of poly(vinyl chloride) based on Christiansen effect." (Samitsu et al., 2018) [11. The paper additionally provides refractive indices of PVC reported in literatures because Christiansen effect has close relationship with wavelength-dependent refractive index, i.e. optical dispersion. The values have considerable range probably depending on samples and determination methods for refractive index. The comprehensive data list is therefore potentially useful for studying refractive index of polymers. (C) 2018 The Authors. Published by Elsevier Inc.

Separation and purification of oilfield produced water (OPW) is a major environmental challenge due to the co-production of the OPW during petroleum exploration and production operations. Effective capture of oil contaminant and its in-situ photodegradation is one of the promising methods to purify the OPW. Based on the photocatalytic capability of graphitic carbon nitride (GCN) which was recently rediscovered, photodegradation capability of GCN for OPW was investigated in this study. GCN was synthesized by calcination of urea and further exfoliated into nanosheets. The GCNs were incorporated into polyacrylonitrile nanofibers using electrospinning, which gave a liquid-permeable self-supporting photocatalytic nanofiber mat that can be handled by hand. The photocatalytic nanofiber demonstrated 85.4% degradation of OPW under visible light irradiation, and improved the degradation to 96.6% under UV light. Effective photodegradation of the photocatalytic nanofiber for OPW originates from synergetic effects of oil adsorption by PAN nanofibers and oil photodegradation by GCNs. This study provides an insight for industrial application on purification of OPW through photocatalytic degradation under solar irradiation. (C) 2018 Elsevier Ltd. All rights reserved.

Porous poly (vinyl chloride) (PVC) particles immersed in organic liquids exhibited bright colors when the refractive indices (RIs) of the liquids were close to the RI of PVC. The particles can separate white light into complementary transmitting and scattering colors. Unlike conventional structural colors resulting from interference of light, the colors, which are independent of the periodic microstructures, were systematically tuned by varying the wavelength-dependent RIs of liquids and covered the entire visible range from 320 to 780 nm. Numerical calculation based on the Mie scattering theory successfully reproduced their transmission spectra, validating the Christiansen effect of these materials. The RI determined by this effect was higher than that of the film sample and representative values in literature. The study reveals new and undiscovered RI-related features of polymers and demonstrates that the Christiansen effect will provide a simple but valuable method to study the dispersion state of polymer particles in liquids. (C) 2018 Elsevier Ltd. All rights reserved.

高分子多孔質体は、空孔・空隙がもたらす高い比表面積や表面・界面構造に裏付けされた特異な化学的、物理的性質によって、物性機能の多様性の広がりが生みだす。本稿では、微細なメソ細孔を形成する新たな相分離技術として我々が開発してきた、「急速凍結ナノ結晶化法」を紹介する。

The facile fabrication of mesoporous materials using commodity polymers and improvements in the thermal and mechanical stabilities of the mesopores remain challenging. Herein, we report thermally stable, mechanically robust mesoporous monoliths made of commercially available poly(ether sulfone) (PES). A PES solution dissolved in N,N-dimethylformamide spontaneously formed a physical gel upon cooling to moderate temperature and/or mixing with benzene due to partial crystallization of PES. Mesoporous monoliths obtained from this gel had a reticular structure composed of nanofibers with an average diameter of 18 nm in conjunction with a high specific surface area of 206 m(2)/g. The dense reticular structure showed a large total pore volume of 2.95 cm(3)/g, including a significant mesopore volume of 0.52 cm(3)/g. The nanofiber structure together with the high glass transition temperature of PES significantly enhanced the thermal stability of the mesopores, 80% of which were maintained even after aging at 150 degrees C for 600 h.

Silica gels and glasses doped with SiAlON phosphors have been synthesized by the sol-gel method. Only after half a day of supercritical drying, the dried gels with many mesopores and high surface-specific area were obtained. The chromaticity of the gels can be controlled to vary widely from blue to yellow by changing the heating temperature, SiAlON concentration, and sample thickness. The thermal dependence of photoluminescence of the glass is similar to that of SiAlON powder.

“Research activity is like treasure hunting”, is a quote from my supervisor that was the starting point of my research career. Development of new materials for practical applications is really a tough challenge. This is a short story of how I gained scientific knowledge and learned new research techniques, and an account of what I want to become in the future.

Polymer nanoparticles are readily obtainable by rapidly mixing a dilute polymer solution and a poor solvent. The nanoparticles of poly(vinylphenol), poly(vinylidene fluoride), and emeraldine base polyaniline prepared by nanoprecipitation become sticky when their diameters decrease down to a few tens of nanometers, and such polymer nanoparticles spontaneously assemble into rigid fractal networks of the nanoparticles. By filtering these fibrous nanoparticle networks on a microfiltration membrane, ultrafiltration membranes with a thin free-standing filter cake layer made of nanoparticles are obtainable. The nanoparticle membranes are robust at least up to the applied pressure of 2 MPa and can separate 99% of 10 nm Au nanoparticles from the aqueous dispersion at the flux of more than 1835 L m(-2) h(-1) even at very low pressure difference of 0.08 MPa. (c) 2015 Wiley Periodicals, Inc. J. Polym. Sci., Part B: Polym. Phys. 2015, 53, 615-620

Hydrophobic mesoporous polymer nanofibre networks were converted to hydrophilic ones by a mild sulfonation reaction. The resultant mesoporous polystyrene with a large free surface area effectively captured water-soluble dye molecules and allowed aromatic compounds to rapidly permeate into the internal binding sites.

相分離による多孔体形成技術は、高分子材料の高付加価値化のためのキーテクノロジーである。本稿では、高分子溶液の急速冷却をコアとする新たな多孔体形成技術「ナノ結晶化相分離法」と分離機能材料としての高分子メソ多孔体の可能性を紹介する。

Various conventional reactions in polymer chemistry have been translated to the supramolecular domain, yet it has remained challenging to devise living supramolecular polymerization. To achieve this, self-organization occurring far from thermodynamic equilibrium-ubiquitously observed in nature-must take place. Prion infection is one example that can be observed in biological systems. Here, we present an 'artificial infection' process in which porphyrin-based monomers assemble into nanoparticles, and are then converted into nanofibres in the presence of an aliquot of the nanofibre, which acts as a 'pathogen'. We have investigated the assembly phenomenon using isodesmic and cooperative models and found that it occurs through a delicate interplay of these two aggregation pathways. Using this understanding of the mechanism taking place, we have designed a living supramolecular polymerization of the porphyrin-based monomers. Despite the fact that the polymerization is non-covalent, the reaction kinetics are analogous to that of conventional chain growth polymerization, and the supramolecular polymers were synthesized with controlled length and narrow polydispersity.

高分子溶液の急速冷却をコアとする多孔体形成技術（ナノ結晶化相分離法）を開発し、300 m2/gを超える大きな比表面積を持った高分子メソ多孔体を製造することに成功した。高分子メソ多孔体では、直径が約10 nmのナノファイバーが無数に分岐して連結した3次元の緻密なネットワーク構造が形成されている。この特徴的なナノ構造の結果、多孔体の内部に連通したナノ細孔が形成され、液体や気体の浸透や拡散性が大幅に向上することが分かった。

Various conventional reactions in polymer chemistry have been translated to the supramolecular domain, yet it has remained challenging to devise living supramolecular polymerization. To achieve this, self-organization occurring far from thermodynamic equilibrium-ubiquitously observed in nature-must take place. Prion infection is one example that can be observed in biological systems. Here, we present an 'artificial infection' process in which porphyrin-based monomers assemble into nanoparticles, and are then converted into nanofibres in the presence of an aliquot of the nanofibre, which acts as a 'pathogen'. We have investigated the assembly phenomenon using isodesmic and cooperative models and found that it occurs through a delicate interplay of these two aggregation pathways. Using this understanding of the mechanism taking place, we have designed a living supramolecular polymerization of the porphyrin-based monomers. Despite the fact that the polymerization is non-covalent, the reaction kinetics are analogous to that of conventional chain growth polymerization, and the supramolecular polymers were synthesized with controlled length and narrow polydispersity.

Composites between carbon fibers (CFs) and heterogeneous materials have been widely studied and their fabrication techniques have been developed. However, their hydrophobic surfaces make it difficult to disperse CFs into hydrophilic resins, which results in weak junctions with ceramics. To develop high-strength composite fibers, it is important to design interfacial chemical bonds. Thus, surface-modification techniques of CFs have recently become the main focus and their interfaces have been characterized by various analytical methods. In this Minireview, various techniques that modify the CF surface by coating with inorganic polymers (metal oxide compounds) are highlighted, and the applications of novel nanocomposite fibers are also described. Furthermore, interfacial bonds between CFs and polymer resins are reviewed and discussed in terms of CF-reinforced plastics and their future prospects.

Composites between carbon fibers (CFs) and heterogeneous materials have been widely studied and their fabrication techniques have been developed. However, their hydrophobic surfaces make it difficult to disperse CFs into hydrophilic resins, which results in weak junctions with ceramics. To develop high-strength composite fibers, it is important to design interfacial chemical bonds. Thus, surface-modification techniques of CFs have recently become the main focus and their interfaces have been characterized by various analytical methods. In this Minireview, various techniques that modify the CF surface by coating with inorganic polymers (metal oxide compounds) are highlighted, and the applications of novel nanocomposite fibers are also described. Furthermore, interfacial bonds between CFs and polymer resins are reviewed and discussed in terms of CF-reinforced plastics and their future prospects.

DLC膜は，硬度，平滑性，耐摩耗性などの機械特性だけでなく，ガスバリヤ性や抗血栓性などの優れた性質が見出されており，工作機器，飲料水ボトル，医療機器などに幅広く応用されている．本稿では，DLC膜の多孔化という視点に立ち，耐有機溶媒性のナノろ過膜としての応用について紹介した．

Under certain conditions, metal hydroxides may adopt a unique crystalline morphology known as nanostrands. These extremely fine nanofibers, no more than 2.5 nm in diameter and a few micrometers in length, form spontaneously in aqueous solutions of certain transition metal ions (Cd2+, Cu2+ and Zn2+). They typically possess a significant quantity of positive charges, a property which renders them highly dispersible in water, much like organic polyelectrolytes. Various composite fibers are obtainable from combinations of metal hydroxide nanostrands and negatively charged compounds, and these fibers may be converted into ultrathin free-standing membranes with a variety of useful applications. In addition, the nanostrands themselves can be formed into uniform nanofibrous sheet structures through a filtration process. These sheets are useful as sacrificial layers in the fabrication of free-standing polymer and nanoparticle membranes and are also stable substrates for the plasma deposition of metals and diamond-like carbon (DLC). DLC membranes exhibit surprisingly high permeation with organic solvents, and they are also expected to be useful in industry as filtration membranes for organic solvent and water contaminated with oil. This article reviews the initial work associated with the discovery of metal hydroxide nanostrands, fundamental properties and various applications to separation technology. (C) 2013 Elsevier B.V. All rights reserved.

Tin oxide (SnO2) hollow nanofibers doped with cerium oxide (CeOx) were synthesized to study the impact of CeO2 additives on their chemical sensing response. X-ray diffraction analysis and Raman scattering spectroscopic analysis showed that crystallization of CeO2 in the fiber composites was observed only when the Ce concentration was greater than 6 mol%. Also, maximum sensing response to ethanol was seen in the fiber composites with 6 mol% addition of Ce. Accordingly, we have discussed the possible explanations for this, including the role of crystalline CeO2 as a surface catalyst, and the role of hydrogen liberated during the dehydrogenation reaction of ethanol diffusing into the SnO2 lattice. The results obtained in this study indicate that SnO2-CeO2 nanofiber composites are potential candidates for use as high-sensitivity gas sensors. (C) 2013 Elsevier B.V. All rights reserved.

日本膜学会からの依頼があり、多孔性ダイヤモンド状カーボン膜の将来展望について、関連する分離膜の技術動向と資源・エネルギー関連の環境保全問題を議論しながら解説した。

There are increasing requirements worldwide for advanced separation materials with applications in environmental protection processes. Various mesoporous polymeric materials have been developed and they are considered as potential candidates. It is still challenging, however, to develop economically viable and durable separation materials from low-cost, mass-produced materials. Here we report the fabrication of a nanofibrous network structure from common polymers, based on a microphase separation technique from frozen polymer solutions. The resulting polymer nanofibre networks exhibit large free surface areas, exceeding 300 m(2) g(-1), as well as small pore radii as low as 1.9 nm. These mesoporous polymer materials are able to rapidly adsorb and desorb a large amount of carbon dioxide and are also capable of condensing organic vapours. Furthermore, the nanofibres made of engineering plastics with high glass transition temperatures over 200 degrees C exhibit surprisingly high, temperature-dependent adsorption of organic solvents from aqueous solution.

The mechanochemical surface functionalization of iron oxides with disordered lattices on bare iron (Fe) particles was investigated using simple milling processes to clarify the formation mechanism of the oxide layer and investigate the near-surface models with different states. The homogeneous alpha-Fe particles at On bate Iron surface the milling equilibrium were first prepared under an argon atmosphere. After the subsequent milling reaction of the particles with oxygen molecules, the surface analyses by X-ray diffraction and Raman and X-ray photoelectron spectroscopies revealed that the near-surface layers consisted of two iron oxide phases (alpha-Fe2O3 and Fe3O4) through oxygen atom diffusion, and the alpha-Fe2O3. was dominantly grown on the near surface. During the initial reaction, the signals from an electron spin resonance suggested the dangling bond formation on alpha-Fe2O3. The oxygen atoms effectively induce disordered lattices in the local area to form oxidized Fe3+ clusters, and the geometric distortion formed the dangling bonds, which were theoretically supported by a molecular orbital calculation to elucidate the increase in the unpaired electron sites on the alpha-Fe2O3.,Therefore, the defective Fe3+ ions induced by the lattice mismatching between the clusters and bare alpha-Fe are found to form the disordered lattice that contains the oxygen atoms with unpaired electrons, which are successfully induced by the near-surface strain based on the simple mechanochemical reactions. The patterns of surface activation of the Fe particle surfaces by oxidization will be capable of novel chemical reactions by selective oxygen insertion as well as deep oxidation.

Orientational order parameter decreases by mixing the fluorescent molecules which is bigger than nematic molecules. Thus, we can manipulate the fluorescent molecules into certain space where orientational order was decreased by photoisomerization of azobenzene. We call this operation "Molecular Manipulation." When the gold nano particles substitute for the fluorescent molecules, they gather into the higher ordered region. We try to manipulate them and make a photonic regular arrangement using the interference fringe of UV laser.

Chemical, petrochemical, energy, and environment-related industries strongly require high-performance nanofiltration membranes applicable to organic solvents. To achieve high solvent permeability, filtration membranes must be as thin as possible, while retaining mechanical strength and solvent resistance. Here, we report on the preparation of ultrathin free-standing amorphous carbon membranes with Young's moduli of 90 to 170 gigapascals. The membranes can separate organic dyes at a rate three orders of magnitude greater than that of commercially available membranes. Permeation experiments revealed that the hard carbon layer has hydrophobic pores of similar to 1 nanometer, which allow the ultrafast viscous permeation of organic solvents through the membrane.

Conducting polymers can self-assemble into nanofibrous structure by pi-pi interaction between polymer backbones. A nematic liquid crystal solvent offers the large-scale alignment of the nanofibers. A well-organized nanofibrous structure of the conducting polymers gives high field-effect mobility irrespective of alkyl side chain length, addressing the importance of self-assembled nanostructures of polymers.

Ultrafiltration membranes with a thickness of several tens of nanometers are prepared from cross-linked poly(4-vinylpyridine) gel using a flat and smooth sacrificial layer of metal hydroxide nanostrands. The membranes have a network structure with pores sizes of approximately 2.0 +/- 1.0 nm and can separate small proteins and organic dyes at a surprisingly high filtration rate.

Freestanding cross-linked polystyrene nanoparticle membranes with a thickness of 80 nm and precisely controlled pores were prepared by filtering polystyrene nanoparticles on a microfiltration membrane by using a sacrificial layer of metal hydroxide nanostrands. The membranes could quickly separate small proteins and gold nanoparticles, showing surprisingly sharp cut-off properties.

Collective long-range interactions between micrometre-sized impurities in liquid crystals result from the elastic distortion of the liquid-crystalline order1-8. For substantially smaller polymeric impurities, what is relevant is not the elastic interaction between them but the coupling between the scalar nematic order parameter S and the polymer concentration phi. This coupling originates from local molecular interactions, but becomes long ranged because the total polymer concentration is conserved over the whole sample. Here, we propose a new mechanism by which the spatial variation of S generates a force, mediated by the coupling between S and phi, that transports nanoscale polymeric impurities. We have designed a prototype of a molecular manipulator that moves molecules along spatial variations of the scalar order parameter, modulated in a controlled manner by spot illumination of an azobenzene-doped nematic phase with ultraviolet light. We also demonstrate the use of the manipulator for the measurement of the anisotropic diffusion constant of a polymer in the nematic phase. The manipulator can control the spatial variation of the polymer concentration, thus showing promise for use in the design of hybrid soft materials.

We report field-effect carrier transport of poly(3-alkylthiophene) nanofiber devices, focusing on the effect of the alkyl side chain length. In contrast to thin film devices reported previously, nanofiber devices with both network and single nanofiber geometry give mobilities above 0.01 cm2/Vs, little influenced by alkyl chain length. These high mobilities result from the well-organized microstructure of the nanofiber, regardless of the alkyl chain length.

We have developed a whisker method using a nematic liquid crystal solvent and achieved large-scale onedimensional alignment of conducting polymer nanofibers. The polymer chains crystallized nearly one-dimensionally and self-assembled into nanofibers consisting of stacked polymers that preserved their alignment. Anisotropic crystallization in a nematic liquid crystal enabled us to obtain macroscopic alignment of conducting polymer nanofibers normal to the director. AFM images revealed several nanofibers 10 nm in height aligned normal to the director and bundled into a one-dimensional fibrillar structure 100 nm in height. The unidirectional alignment of the nanofibers enabled the emission of polarized fluorescence under illumination by unpolarized light.

The whisker method using anisole solvent was developed for effective production of high-aspect-ratio poly (3-alkylthiophene) (P3AT) nanofibers, and alkyl chain length dependence on nanofiber formation and their properties were fully investigated. The nanofibers have an anisotropic cross section of 3-4 nm height and 24-27 nm width, which slightly increase with the alkyl chain length, and the aspect ratio reaches 100-1000. The nanofibers consist of more than 104 parallel stacks of the extended polymer backbones along the nanofiber long axis and of 2-3 laminated layers of the polymer backbones separated by alkyl side chains. The nanofiber formation originates from quasi-one-dimensional crystallization of P3ATs induced by both an attractive pi-pi* interaction between polymer backbones and the crystallization of alkyl side chains. Carrier transport properties of a AuCl3-doped nanotiber network and single nanofibers, both of which are explained by a quasi-one-dimensional variable-range hopping (VRH) model irrespective of alkyl chain length, indicate that the origin of the random potential that localizes the carriers should be attributed not to the bridges between nanotibers but to some factor involved in a single nanofiber.

A molecular tube was synthesized by cross-linking alpha-cyclodextrins (alpha-CDs) of a polyrotaxane with epichlorohydrin in dimethyl sulfoxide (DMSO). The obtained molecular tube was characterized with H-1 and C-13 NMR, size-exclusion chromatography, and UV-vis absorption titration with iodine. The use of DMSO afforded greater cross-linking efficiency than that with the conventional aqueous NaOH. The inclusion-dissociation behavior of the molecular tube and alpha-CD with poly[(ethylene oxide)-ran-(propylene oxide)] (PEOrPO) having a central azobenzene moiety was investigated using induced circular dichroism measurements. The PEOrPO with azobenzene was included in the tube cavity, resulting in the exhibition of induced circular dichroism. This result suggests the stable inclusion of propyrene oxide units with a molecular tube for the first time. Higher temperature and higher molecular weight of PEOrPO yielded lesser amounts of the inclusion complexes with the molecular tube. The enthalpy change of inclusion complexation of the molecular tube with the PEOrPO-Az was calculated to be -3.6 kJ mol(-1) per PO unit, which is similar to that with a linear alkyl chain.

We prepared conducting polymer nanofibers by means of whisker formation in a solution by using solvent-soluble conducting polymers with alkyl or alkoxy side chains. A morphological characterization using an atomic force microscope indicated that they have one-dimensional nanofibrillar structures with typical heights of 3-10 nm. The conductivity of a single poly(3-hexylthiophene) (P3HT) nanofiber was measured using 300-nm-spacing Pt electrodes and the conductivity of 0.25 S/cm at 290 K was achieved by chemical doping using nitrosoniurn tetrafluoroborate. Considering the temperature dependence of the conductivity, the carrier transport in the single nanofiber was explained by a quasi-one-dimensional variable range-hopping model. (c) 2007 Elsevier B.V All rights reserved.

The dissolution behavior of polyrotaxanes, consisting of a-cyclodextrin and poly(ethylene glycol), with different molecular weights (2000 and 35,000) was investigated. Halogen-containing ionic liquids, such as chlorides or bromides, were found to be good solvents for polyrotaxanes, regardless of their cations. Dissolution required a high temperature (above 90 degrees C), while intensive heating over 105 degrees C seemed to cause decomposition of the polyrotaxane. The discovery of new solvents for polyrotaxane was applied in the preparation of ionic liquid-containing slide-ring gels (SR gels), that is supramolecular networks of polyrotaxane swollen with ionic liquids, using a devised "non-drying" technique accompanied by solvent exchange. Significant swelling of the SR gels with the ionic liquids was confirmed by dynamic mechanical measurements. (c) 2006 Wiley Periodicals, Inc.