Search

Herein, we succeeded in reproducibly synthesizing palladium nanoparticles with narrow size distribution inside metal–organic frameworks (MOFs) by using pressured H2 gas as a reductant. In addition,...

Control of structural transitions in flexible metal–organic frameworks (MOFs) on a substrate is crucial for controlling their properties for the development of MOF-based applications. In this study, we investigate the structural transition of directly formed flexible MOF crystals on a metal ion-doped polymer substrate. Utilizing hydrolyzed polymer substrates results in the formation of MOF crystals with no structural transition by the adsorption/desorption of guest molecules in their pores. Results suggest that the polymer chains of the substrate are entangled in the obtained MOF crystals, resulting in MOF crystals showing no structural transition by the adsorption/desorption of guest molecules in the pores. By controlling the temperature for the hydrolysis reaction of the polymer substrate, the number of polymer chains entangled with MOF crystals decreases, resulting in a dynamic structural transition of the resulting MOF crystals on the substrate. These results provide insights into the effect of the polymer substrate on the properties of MOF crystals on a two-dimensional substrate.

We describe a simple bottom-up strategy to generate [Au(SPh)]n (SPh: thiophenolate) coordination polymer (CP) based thin films by employing an interfacial self-assembly on a nylon substrate. This m...

In this study, we succeeded in the crystal surface modification of metal–organic framework (MOF) with an organic polymer by site-specific radical polymerization. A MOF was selected with interpenetrated structure containing a naphthalenediimide moiety with electron accepting capability. N, N-dimethylaniline, as an electron donating guest, induced electron transfer to the napthalenediimide moiety, generating radical anions on the pore and crystal surfaces, initiating radical polymerization. The resulting composite was examined in detail with XRD, TG, TEM, ICP, IR, gas adsorption, and fluorescent measurements, demonstrating that an organic polymer was generated only on the crystal surface, preserving the original porous property. In addition, higher structural stability in response to H2O was observed after polymer wrapping.

Crystal conversion of metal-organic frameworks (MOFs) between different crystal topologies on a polymer substrate has been successfully achieved by localized dissolution of MOF crystals followed by a rapid self-assembly of framework components. Upon addition of the desired organic linkers to the reaction system containing MOF crystals on the substrate, reversible crystal conversion between the [Cu2(btc)3]n and [Cu2(ndc)2(dabco)]n frameworks (btc = 1,3,5-benzene tricarboxylate, ndc = 1,4-naphthalene dicarboxylate, dabco = 1,4-diazabicyclo[2.2.2]octane) could be routinely achieved in high yields. Most surprisingly, in the case of conversion from the [Cu2(ndc)2(dabco)]n to [Cu2(btc)3]n frameworks, the [Cu2(btc)3]n crystals with unique shapes (cuboctahedron and truncated cube) could be prepared using butanol as a reaction medium.

Hydrogenation reaction under low H2 pressure atmosphere is of great interest from a safety view point because H2 gas is highly flammable in air and shows explosion triggered by spark, heat or sunlight. In this work, Rh complex catalyst- MOF hybrid was newly synthesized and used as catalyst for hydrogenation of alkene substrates. Thanks to the activation of Rh complex catalyst during the immobilization process and intrinsic gas condensation property of MOF, the resulting composite showed much higher catalytic activity than the complex catalyst itself. Noteworthy, the composite can maintain its catalytic activity even under low H2 pressure that cannot support the reaction with the complex catalyst alone. Furthermore, in contrast to the complex catalyst, the composite maintained its catalytic activity even without solvent, providing environmentally friendly approach to catalysis.

A simple composition control route to mixed-lanthanide metal-organic frameworks (MOFs) was developed based on an interfacial reaction with mixed-lanthanide metal ion-doped polymer substrates. By controlling the composition of lanthanide ion (Eu3+ and Tb3+) dopants in polymer substrates to be used as metal ion precursors and scaffolding for the formation of MOFs, [EuxTb2−x(bdc)3(H2O)4]n crystals with a tunable metal composition could be routinely prepared on polymer substrates. Inductively coupled plasma (ICP) measurements revealed that the composition of the obtained frameworks was almost the same as that of the initial polymer substrates. In addition, the resulting [EuxTb2−x(bdc)3(H2O)4]n crystals showed strong phosphorescence because of Eu3+ transitions, indicating that the energy transfer from Tb3+ to Eu3+ ions in the frameworks could be achieved with high efficiency.

In this work, we succeeded for the first time in immobilizing an ionic liquid (IL) in a metal–organic framework (MOF) by using ion-exchange reactions. Interestingly, the resulting composites showed catalytic activities that were not observed with the original IL or the IL physically adsorbed on the MOF, implying that its ionic state was drastically changed upon immobilization.

The growth of metal-organic frameworks (MOFs) on a metal ion-doped polymer as a precursor and support substrate was investigated based on mechanistic and kinetic analyses. The studies were performed by varying the reaction temperature and the concentrations of the organic ligand and nucleation-promoted additive. Using the NH

Nickel-nanoparticle-containing polyimide composite films were prepared by liquid-phase reduction of Ni2+ ions with potassium borohydride (KBH4). The nanoparticles were amorphous with diameters of approximately 10–20 nm, depending on the KBH4 concentration and reduction temperature. At high KBH4 concentrations, the nanoparticles appeared to contain various nickel boride species. The number of nanoparticles and Ni content both increased upon repeated adsorption/reduction of Ni2+ ions, where the particle growth was inhibited by the rigid polymer chain and the formation of smaller particles was favored.

Alkane-selective colorimetric change from white to pink was observed with the simple system consisting of UiO-66 and 7-azaindole. The colorimetric change was strongly enhanced with increasing amounts of defects inside the UiO-66 framework, which indicates that interaction between the defects and 7-azaindole plays a pivotal role for this phenomenon.

We developed a novel humidity sensor using a heat pipe on the basis of a new measurement principle. The sensor measures humidity using the condensation heat of water on the surface of the heat pipe. Theoretical equations describing the measurement principle using a simple model were derived. Comparison experiments were performed for dew points in the range of 50 °C to 80 °C using a humidity standard generator based on the International System of Units (SI). The standard value and the value calculated using the theoretical equations were in reasonable agreement with each other (with a difference within 0.5 °C). The difference was further decreased to within 0.2 °C by employing a calibration curve using multiple regression analysis. The sensor was also experimentally compared to a psychrometer, confirming that the two devices have similar performance. The sensor does not require the replacement of wicks or a water supply, and the measurement region is made of metal, making the sensor superior to the psychrometer in terms of low maintenance, and long lifetime and high durability at high temperatures and high humidities.

We report a new paradigm for the synthesis of metal–organic framework (MOF) crystals with controlled thickness by utilizing interfacial self-assembly of frameworks on metal ion-doped polymer precursors. The approach involves preparation of metal ion-doped polymer precursors through ion-exchange reactions and synthesis of MOF crystals by immersion into solutions containing organic ligands. The thickness of the resulting MOF crystals can be readily controlled by the number of doped-metal ions in the polymer precursors. MOF crystals could be very important and potentially useful for applications, and the present approach based on interfacial self-assembly could significantly advance MOF crystal preparation techniques.

We report a unique method for the site-selective growth of metal–organic frameworks (MOFs). The site-selective growth of MOFs can be achieved by fabricating a pattern of polymer photoresist on the metal-ion-doped polymer substrate and then constructing frameworks by immersion in an organic ligand solution.

In situ formation of Cu–Ni alloy nanoparticles with controlled composition in thin polyimide layers was investigated. The ferromagnetic properties of the nanoparticles were found to depend on the composition and the interparticle distance between the nanoparticles.

The widespread demand of coating, corrosion protection, metallurgy, and microelectronics industries for electrodeposition has been met by developing current successful, commercially-available deposition baths containing metallic salts at higher concentration, highly concentrated supporting electrolytes, and various kinds of organic additives, enabling higher deposition rate, greater current efficiency, and long-term stability for the baths. However, developing effective deposition systems for high-performance electrodeposition is challenging, because, (1) in product point of view, the additives sometimes and rather often cause mechanical and/or electrical problems for deposited metal circuit elements due to inclusion of such additives during deposition process, and, (2) in processing point of view, commercial electrodeposition setups cause huge amount of detrimental effluents that can be a serious environmental and cost problems. These issues may be a product of compromise that is particularly relevant for structure and properties of the deposited metals (film resistivity, surface roughness, mechanical and adhesion strength), and processing (costs and manufacturing steps including rinsing and detrimental effluents treatment). The current solution-based electrodeposition systems are generally incapable of significantly increasing reaction rate (deposition rate constant) form dilute electrolyte solution, because diffusion-limiting current that needs to be higher for industrial manufacturing depends on the concentration (and its gradient) of electrolyte solution, which can be described by Fick’s first law in a steady-state electrodeposition. Additionally, current electrodeposition systems are optimized for large area substrate and mass production manufacturing, thereby cannot be suitable for small-lot, on-demand, and multi-product microfabrication. These have inspired the use of polyelectrolyte membranes to encapsulate metallic ions within inside their channels to concentrate from electrolyte solution while maintaining efficient ion transport properties owing to high density anionic counterparts inside channels and the swelling nature of the membrane.We now show that when the polyelectrolyte membrane does not anchor itself to the cathode substrate, stable electrodeposition of metals on cathode surface is achieved, not as much like a solution-phase electrodeposition, resulting in a new type of solid-state electrodeposition (SED) system (Fig. 1). The SED system consists of cathode electrode, polyelectrolyte membrane (PE), electrolyte solution, and anode electrode.PE works as an additional interfacial phase, in which metal ions are transferred through ion exchange reaction based on concentration gradient of metal ions bound with sulfonic acid functional groups in PE layer. Most important feature of the use of PE at the electrode surface is their ability for metal ions to be concentrated in inner ion transport channels with high density sulfonic anions inside the channels (Fig.1). In the current contribution, we describe transfer process of copper ions between electrodes where the additional PE-solution interfacial layer has been introduced to explain concentration behavior of PE layer for copper ions and electrodeposition characteristics in the present system. From detailed theoretical (both thermodynamic and kinetic) and experimental study regarding with the ion concentration process for PE membrane suggest that (1) the “ion penetration” process is slower than ion exchange (diffusion) process inside PE layer and is therefore rate-determining step for ion concentration, and (2) ion penetration rate increases exponentially as the concentration of copper ions in PE layer decreases.The effect of cation concentration, temperature, and electrochemical deposition conditions on the current efficiency, deposition rate, growth process and morphology of the films has been investigated to optimize the deposition conditions to achieve higher deposition rate. This strategy can be suitable for small-lot, on-demand, and multi-product microfabrication. Figure 1

Aberrant activation of RAS signalling pathways contributes to aggressive phenotypes of cancer cells. The RAS-targeted therapies for cancer, therefore, have been recognised to be effective; however, current developments on targeting RAS have not advanced due to structural features of the RAS protein. Here, we show that expression of NRAS, a major isoform of RAS, can be controlled by photo-irradiation with an anionic phthalocyanine, ZnAPC, targeting NRAS mRNA. In vitro experiments reveal that ZnAPC binds to a G-quadruplex–forming oligonucleotide derived from the 5′-untranslated region of NRAS mRNA even in the presence of excess double-stranded RNA, which is abundant in cells, resulting in selective cleavage of the target RNA’s G-quadruplex upon photo-irradiation. In line with these results, upon photo-irradiation, ZnAPC decreases NRAS mRNA and NRAS expression and thus viability of cancer cells. These results indicate that ZnAPC may be a prominent photosensitiser for a molecularly targeted photodynamic therapy for cancer., Hyperactivity of the gene NRAS contributes to the proliferation and metastatic nature of many types of cancer cells. Here, the authors show that NRAS can be controlled by an anionic phthalocyanine coordinating Zn2+ in combination with photo-irradiation.

We describe the use of ion-exchangeable, highly cross-linked polymer films as a matrix for the synthesis of nanocomposite thin films and patterns with embedded Cu and Ni nanoparticles. We have successfully controlled the size of metal nanoparticles and thus optical and magnetic properties of the films by varying the initial amount of doped metal ions.

We report a novel method to prepare silicon quantum dots (Si-QDs) having excellent stability in water without organic-ligands by simultaneously doping phosphorus and boron. The codoped Si-QDs in water exhibit bright size-tunable luminescence in a biological window. The luminescence of codoped Si-QDs is very stable under continuous photoexcitation in water.

The surface structure of P and B codoped colloidal Si-NCs are studied by photoluminescence (PL) in hydrofluoric acid (HF) solution and X-ray photoelectron spectroscopy (XPS). We find that codoped Si-NCs are much more stable in HF solution than undoped, P-doped, and B-doped Si-NCs. The PL study combined with XPS results reveal that a high B concentration layer is formed on the surface of codoped Si-NCs and the layer acts as a kind of inorganic atomic ligands for Si-NCs. The high B concentration layer makes Si-NCs hydrophilic and dispersible in polar liquids. Furthermore, the layer effectively protects Si-NCs from oxidation in solution and in air.

A three-dimensional metal–organic framework (MOF) consisting of pillared square-grid nets based on paddle-wheel units was synthesized by interfacial self-assembly of the frameworks on a metal-ion-doped polymer substrate. Although this type of Cu-based MOF is typically synthesized by a two-step solvothermal method, the utilization of a metal-ion-doped polymer substrate as a metal source for the framework allowed for the one-pot growth of MOF crystals on the substrate. The morphology of the obtained MOF crystals could be controlled from tetragonal to elongated tetragonal with different aspect ratios by changing the concentrations of the dicarboxylate layer ligands and diamine pillar ligands. The present approach provides a new route for the design and synthesis of MOF crystals and thin films for future applications such as gas membranes, catalysts, and electronic devices.

Gold nanoparticles modified with thiol-terminated polystyrene (AuPS) were synthesized and applied to the colorimetric detection of perfluorooctanoic acid (PFOA). The color change of the AuPS solution from red to blue-purple upon addition of PFOA was easily confirmed by the naked eye. Using several acids and fluorinated compounds, the detection system was shown to be selective for PFOA and tridecafluoroheptanoic acid, which suggests that both a highly acidic carboxyl group and a fluorocarbon group are required for the color change. Transmission electron microscopy (TEM) suggested that the addition of PFOA caused detachment of the polystyrene layer from the surface of the gold nanoparticles, which resulted in interparticle aggregation.

Magnetic composite nanostructures composed of a dielectric matrix containing magnetic nanoparticles offer opportunities for the fabrication of next-generation magnetic devices, in addition to providing a fundamental understanding of nanomagnetism. However, a synthetic strategy for the fine-tuning of such composite nanostructures is required. Herein, we report an analytical study on the structural tuning of composite thin layers of a polyimide matrix containing nickel nanoparticles. Control of the composite layer microstructure was achieved by decomposition of the polyimide matrix using the nickel nanoparticles as a catalyst, which resulted in weight loss and thus shrinkage of the composite layer volume. Several analytical experiments were conducted for films annealed at a constant temperature for different time intervals and hydrogen partial pressures to identify the chemical structures of decomposition products and to elucidate the reaction mechanism of the metal-catalyzed decomposition process. The deco...

We demonstrate the formation of a new type of surfactant-free colloidal silicon nanocrystal (Si-NC). The characteristic structural feature of the Si-NCs is simultaneous doping of phosphorus (P) and...

Molecular imprinting technique was applied for the preparation of polymer beads selected for a triazine herbicide, atrazine. Polystyrene, poly(methyl methacrylate) and poly(ethylene glycol) were examined as polymeric diluents, and the morphology of the resultant molecularly imprinted polymers was investigated by scanning electron microscopy. Among the examined polymeric diluents, styrene was shown to be favorable for obtaining monodispersed spherical polymer with high retention ability for atrazine.

We report a novel approach for synthesizing inorganic nanoparticle/metal-organic frameworks (MOFs) heterostructured nanocomposites by self-assembly of MOFs on nanoparticles. This approach involves the synthesis of Au nanoparticles and preferential growth of [Cu(3)(btc)(2)](n) frameworks consisting of Cu(2+) ions and benzene-1,3,5-tricarboxylate (btc) on nanoparticles. Aggregates consisting of 11-mercaptoundecanoic acid (MUA)-stabilized Au nanoparticles linked by Cu(2+) ions were necessary for preferential self-assembly of [Cu(3)(btc)(2)](n) frameworks on the aggregates, resulting in the formation of Au nanoparticles/[Cu(3)(btc)(2)](n) nanocomposites. The present approach was confirmed to be applicable for other hybrids consisting of Au nanoparticles and tetragonal [Cu(2)(ndc)(2)(dabco)](n) frameworks.

Polyaniline–silver nanocomposites were synthesized in the form of colloidal particles by the facile one-step aqueous chemical oxidative dispersion polymerization of aniline using silver nitrate as an oxidant and poly(vinyl alcohol) as a colloidal stabilizer. Aniline monomer was oxidized by silver ions, yielding polyaniline and elemental Ag simultaneously. The synthesized nanocomposite particles were colloidally stable over 2 years and transmission electron microscopy studies indicated the production of spherical, plate and rod-shaped polyaniline–silver nanocomposite particles with a silver core–polyaniline shell morphology. The conductivity of a pressed pellet of the nanocomposite particles using the conventional four-point probe technique was 1.4 × 10 −2 S/cm at 25 °C. The nanocomposite particles behaved as a ‘colored’ particulate emulsifier for the stabilization of transparent oil-in-water emulsions.

ガラス基板上に銅微細回路パターンを形成することを目的として，カルボン酸を電子ドナーとする光化学還元法について検討した。銅イオンの光化学還元反応は，UV照射部全面で起こるが，それを水で洗浄するとあらかじめガラス基板上に形成した疎水性のn-octadecyl trimethoxysilaneパターン上にのみ銅析出物が残存した。親水性のガラス表面に析出した銅薄膜は，水のような極性溶媒による洗浄により，選択的にリフトオフされる。析出する銅薄膜の厚さは，UV照射の時間により容易に制御することができる。局部分極曲線の測定の結果，本研究の光化学還元法において混成電位理論が成立することが明らかとなった。

This report describes a new process for ULSI minute copper-wiring formation. It relies on microcontact printing [μCP] of polyethylene glycol bis(1,2,3-benzotriazolylether) [PBTA]—synthesized from polyethylene glycol and benzotriazole—to the surface of copper seed layer, with preferential copper electrodeposition in PBTA-free regions (contact hole and trench) using an acid copper sulfate bath. The copper electrodeposition was done using an insoluble anode in the basic bath without additives. The microcontact printed PBTA on the copper seed-layer surface strongly inhibits copper electrodeposition. Using this process, because of the effect of site-selective printing of PBTA, a minute contact hole can be filled completely with copper without causing voids and seams.

A synthesis method for nanocomposite microspheres containing Ni nanoparticles via chemical surface modification has been developed, by which particle size and interparticle distance for embedded Ni nanoparticles can be systematically controlled. The process relies on introduction of carboxyl acid groups via hydrolysis of matrix polymer, incorporation of Ni ions via ion exchange reaction, hydrogen-induced reduction of doped Ni ions in the sphere followed by Ni nanoparticle-catalyzed decomposition of the surrounding polymer matrix. We demonstrate the formation of Ni nanoparticles in polymer microspheres and structural change of polymer matrix upon reaction by FT-IR, SEM, and cross-sectional TEM studies, and show that initial Ni ion loading determines final nanoparticle size ranging from 3 to 8 nm, which are homogeneously distributed in the whole of the microspheres. The heat-treatment in a hydrogen atmosphere at fixed temperature causes decomposition of the polymer matrix via catalytic reaction of Ni nanopa...

Hydrophilic porous Si is prepared by surface modification with polyethylene oxide (PEO) molecules. The surface modification is confirmed by infrared absorption spectroscopy and photoluminescence spectroscopy. The effect of surface modification on the efficiency of photosensitization of oxygen molecules, i.e., the efficiency of singlet oxygen generation, is studied. The PEO-terminated hydrophilic porous Si is shown to hold the photosensitization ability although the efficiency is reduced by the modification.

Heterojunctions comprising copper thin films and polyimide underlayers are exploited as an important system for generating flexible microelectronic circuit elements. A fully additive-based chemical method that allows metallization of polyimide films with copper by the in situ reduction of copper ions doped in surface-modified polyimide precursors is reported. It is shown that dimethylamine borane is a good reducing agent for copper ions initially complexed with carboxylate anions in the hydrolyzed polyimide layers. This reduction allows diffusion of copper ions towards the film surface to form copper thin films, and simultaneously controls the fabrication of interfacial microstructures between the copper and underlying polyimide. The formation of copper thin films and composite layers is elucidated by glow-discharge optical emission spectrometry depth profiling, scanning electron microscopy, and cross-sectional transmission electron microscopy studies, and it is shown that the final microstructure at the copper/polyimide interface is dependent upon experimental variables: a larger amount of copper ions incorporated into the modified layers and a higher reduction rate result in the formation of a granular layer containing smaller copper nanoparticles near the film surface, The granular layers thus formed are found to play a critical role in achieving strong adhesion between metal thin films and the substrate, owing to the increased contact area and hence the increased work of adhesion between them. These results have important implications for realizing a novel adhesion scheme between deposited metals and underlying dielectrics based on nanoscale interlocking through metal nanoparticles.

In the basic concept of conventional electroplating, the additives, which determine the properties of the deposited film, are included in the plating bath. In this report, ULSI copper minute wiring formation by a new process is described. The process relies on the pre-adsorption of the polyethylene glycol bis (1, 2, 3-benzotriazolylether) [PBTA] synthesized from polyethylene glycol and benzotriazole, and copper electrodeposition from an acid copper sulfate bath without additives. The copper electrodeposition was done using an insoluble anode in the basic bath without additives after PBTA was pre-adsorbed on the silicon wafer with copper seed. The adsorbed PBTA on the surface of the copper seed strongly inhibited copper electrodeposition. In this process, a minute hole can be filled with copper without causing voids and seams due to the effect of site-selective adsorption of PBTA.

Deposition of copper thin films was achieved by a photocatalytic reaction of site-selectively adsorbed TiO(2) nanocrystals for direct fabrication of copper circuit patterns on glass substrates. The nanocrystal monolayers absorbed on hydrophobic surface templates serve as an effective photocatalyst, producing metallic copper and formic acid via oxidation of methanol in solution. The formic acid generated has also been suggested to serve as an electron donor that accelerates copper deposition through a UV-mediated autocatalytic reaction, even after nanocrystals are embedded into the grown copper films. The thickness of the deposited copper films was easily controlled by varying the UV irradiation time, irradiation power, and initial concentration of methanol as a hole scavenger. The process presented herein provides an effective methodology for resist-free, direct metallization of insulating substrates.

Molecularly imprinted polymer gel with embedded gold nanoparticle was prepared on a gold substrate of a chip for a surface plasmon resonance (SPR) sensor for fabricating an SPR sensor sensitive to a low molecular weight analyte. The sensing is based on swelling of the imprinted polymer gel that is triggered by an analyte binding event within the polymer gel. The swelling causes greater distance between the gold nanoparticles and substrate, shifting a dip of an SPR curve to a higher SPR angle. The polymer synthesis was conducted by radical polymerization of a mixture of acrylic acid, N-isopropylacrylamide, N,N'-methylenebisacrylamide, and gold nanoparticles in the presence of dopamine as model template species on a sensor chip coated with allyl mercaptan. The modified sensor chip showed an increasing SPR angle in response to dopamine concentration, which agrees with the expected sensing mechanism. Furthermore, the gold nanoparticles were shown to be effective for enhancing the signal intensity (the change of SPR angle) by comparison with a sensor chip immobilizing no gold nanoparticles. The analyte binding process and the consequent swelling appeared to be reversible, allowing one the repeated use of the presented sensor chip.

Geometrically pure, all-cis poly(phenylene vinylenes) (PPVs) are synthesized by Suzuki-Miyaura-type polycondensation of 2,5-dioctyloxy-1,4-benzenediboronic acid with (Z,Z)-bis(2-bromoethenyl)benzenes, which are prepared by ruthenium-catalyzed (Z)-selective double hydrosilylation of diethynylbenzenes, followed by bromodesilylation of the resulting (Z,Z)-bis(2-silylethenyl)benzenes with N-bromosuccinimide. The all-cis PPVs thus obtained undergo one-way photoisomerization to the corresponding trans-PPVs both in solution and in the solid. This phenomenon is applied to direct microscale patterning of PPVs onto a quartz substrate.

A study aimed at investigating the process of formation of hybrid nanocomposites consisting of a thin polyimide layer containing copper nanoparticles of varying sizes (3−10 nm in diameter) is described. In this system, precursor layers in which copper ions are fully or modestly doped in a chemically modified polyimide matrix are annealed in a hydrogen atmosphere at a constant heating rate. Reduction behavior of doped copper ions and changes in the chemical structure of the matrix film were characterized by inductively coupled plasma atomic emission spectroscopy and Fourier transform infrared spectroscopy, respectively. The results revealed that there is a strong correlation between both the process of reduction to form copper nanoparticles and the dehydration reaction of the matrix that forms heterocyclic imide rings (re-imidization), depending on the initial loading of copper ions. Transmission electron microscopy coupled with nanobeam energy-dispersive X-ray analysis was utilized to observe that upon an...

Rare earth-doped TiO2 thin films have been successfully formed on glass and Si wafer substrates from aqueous solution through equilibrium reaction between metal–fluoro complex and metal oxide, in which Ln3+–ethylenediaminetetraacetic acid (EDTA) complex (Ln: rare earth metal) was added into the reaction solution. Ln/Ti ratio and crystalline structure of the film could be controlled by varying the initial concentration of Ln3+–EDTA complex solution. The obtained Ln-doped films were densely-packed and had no cracks.

Transparent alumina film and fiber were prepared from the inorganic/organic polymer composites as a precursor by heating at 600–1000 °C in air. The composites were composed of basic aluminum chloride (BAC) and methyl cellulose (MC). The composite films were prepared by a casting method of aqueous solution of BAC and MC. An alumina film (40 μm thick) was obtained by heating at 1000 °C for 2 h, which exhibited high transmittance of above 85% in the range of 300–1000 nm. The phase of alumina changed from amorphous to γ-form between 800 and 900 °C. Upon heating at 1150 °C, the alumina transformed to α-form, and the appearance of the alumina film changed to opaque. Colored transparent alumina films were found to be prepared easily from the composite by the introduction of transition metal ions such as Au 3+ and Co 2+ . Transparent and continuous alumina fiber was also obtained by heating of the composite fibers made by wet solution spinning of aqueous solution of BAC and MC.

Three geometrical isomers of poly(9,9-dioctyl-2,7-fluorene ethynylene vinylene) [poly(1)] having (E)-, (Z)-, and gem-vinylene units have been prepared in high regio- and stereoselectivities by polyaddition of 2,7-diethynyl-9,9-dioctylfluorene (1) catalyzed by three kinds of transition metal catalysts. Thus, a palladium catalyst (2), in situ generated from Pd(OAc) 2 , 1,3-dimesitylimidazolinium chloride (SIMes.HCl), and Cs 2 CO 3 , efficiently catalyzes the (E)-selective reaction, giving (E)-rich poly(1) in over 99% selectivity, whereas the reaction using a catalytic amount of RuCl 2 (=C=CHPh)(PPr i 3)2 (3) in the presence of N-methylpyrrolidine forms (Z)-rich poly(1) in over 92% selectivity. On the other hand, a rhodium catalyst [RhCl(PMe 3 ) 2 ] 2 (4) forms poly(1) bearing gem-vinylene linkages in 94% selectivity. The regio- and stereochemical courses well preserve the catalyst nature of 2-4 observed in dimerization reactions of arylacetylenes as prototypes of the present polyaddition processes. All polymers exhibit emission property and high thermal stability.

Highly concentrated nanosized NiO particles have been prepared by means of vacuum evaporation of Ni on NH2-terminated poly(ethylene oxide) matrix film and subsequent purification by removal of a part of the matrix which was soluble in ethanol. TEM observation revealed that the purified composites contain uniformly dispersed NiO particles with an average diameter of less than 5 nm and fairly narrow size distribution. From the analyses including high-resolution TEM, electron diffraction pattern, and X-ray diffraction (XRD), the resultant particles were found to be fcc NiO, and significant lattice expansion was observed. The chemical bonding of amine end groups of the matrix molecules to NiO particle surfaces was suggested by XPS measurements. XRD and differential scanning calorimetry measurements indicate that the matrix structure in the composite is amorphous. This amorphous nature of the matrix could be caused by the restriction of molecular chain mobility through the chemical interaction between NiO part...

Nylon 6 doped with Ag nanoparticles (nylon 6/Ag) was prepared by immersion of nylon 6 in aqueous AgNO3 solution followed by reductive treatment by heating under H2 gas or immersing in an aqueous NaBH4 solution. As a result of either reductions, Ag nanoparticles below 10nm in diameter were successfully dispersed within the nylon 6 matrix. The Ag content and the dispersion state of the Ag nanoparticles can be varied by the concentration of the AgNO3 solutions and the reduction methods, respectively. From the results of the absorbed Ag+ content in nylon 6 via immersion in AgNO3 solution, nylon 6 was found to have some affinity for silver ion. Nylon 6 doped with Ag2S nanoparticles (nylon 6/Ag2S) was also prepared by immersion in AgNO3 aqueous solution and the following immersion of Na2S aqueous solution. Ag2S particles having several nanometers in diameter were dispersed in nylon 6. The nylon 6/Ag2S film showed strong photoluminescence in the near infrared region.

In this work we attempted to prepare binary alloy nanoparticles consisting of Au and Co, which is a typical phase-separation system in a bulk phase diagram, via a vacuum co-evaporation method. The crystal structure and lattice constant of the Au/Co nano-alloys obtained were investigated by means of a high-resolution transmission electron microscope and selected area electron diffraction. We obtained thermodynamically stable Au/Co nano-alloys with A1 structure upon heat-treatment at a certain temperature, and a partial transition from A1 to an ordered L1 0 structure also took place. The results in the present study demonstrated the thermodynamical differences on alloying behavior between bulk and nanoscopic materials.

Herein, we report on direct fabrication of silver circuit patterns on polyimide resin, the method of which relies on potassium hydroxide-induced chemical modification of the polyimide surface to introduce carboxylic acid groups and incorporation of silver ions through subsequent ion exchange followed by UV-irradiation-induced photochemical reaction. In this new, fully additive based strategy, silver thin films consisting of silver nanoparticles are successfully formed on the selected surface sites simply using a photomask. The thickness of modified layers and amount of incorporated silver ions can be systematically controlled through initial potassium hydroxide treatment, thus providing a better method for controlling the degree of metallization. Diffusion of silver ions in the modified polyimide layer during the reduction process is suggested to be responsible for the film formation and the resulting interfacial structures between silver thin films and underlying polyimide layers.

Convenient routes to hydroxy-terminated poly(norbornene)s (PNBEs) have been developed. Hydroboration of PNBEs bearing a terminal vinyl group with 9-BBN followed by oxidation with H2O2/NaOH forms hydroxy-terminated PNBEs in high yields. The parent PNBEs are prepared by ring-opening metathesis polymerization (ROMP) of norbornene using vinylic sulfides as chain-transfer agents (CTAs). On the other hand, ROMP of norbornene using (Z)-1-phenylthio-1-propen-3-ol as a CTA causes one-step synthesis of ω-hydroxy-terminated PNBE, where the molecular weight of polymer depends linearly on the initial feed ratio of CTA to monomer. Similarly, ROMP reactions using (Z)-1-phenylthio-1-propen-3-ols having bromo, amino, and 4-(chloromethyl)benzamido substituents at the para position of the phenyl group as CTAs afford the corresponding α,ω-heterodifunctionalized (heterotelechelic) PNBEs. The resulting PNBEs serve as macroinitiators for anionic ring-opening polymerization (AROP) of e-caprolactone and atom-transfer radical poly...