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A dynamic structural change of double-layered nanosheets containing pH-degradable polymer networks between two layers to single-layered nanosheets was achieved.

Water dispersible K4Nb6O17·3H2O-based Janus nanosheets were successfully prepared and exhibited unique behaviour at the water–air interface and at the water–toluene interface.

Invited for the cover of this issue is the group of Biplab Manna at the University of Kumamoto. The image depicts various kinds of stacking between the metal-organic layers of MOFs. Read the full text of the article at 10.1002/chem.202201665.

Bicontinuous microemulsion (BME)-based hydrogel films were integrated with screen-printed electrodes (SPEs) comprising working, counter, and reference electrodes to form stand-alone, semi-solid-state electrochemical systems that do not require an outer electrolyte solution. The gel network of the BME hydrogel only exists in the microaqueous phase and retains the structure of the entire BME gel. Following gelation, a microaqueous phase with sufficient ionic strength ensured effective ionic conductivity, even in thin gel films. This enabled the electrochemical reaction to proceed using a thin gel film as an electrolyte solution. However, an intact micro-oil phase with no gel network enabled efficient extraction from an external oil solution and exhibited rapid electrochemistry that was comparable to that of a BME solution. Cyclic voltammograms of lipophilic redox species in oil using the gel-integrated SPE system demonstrated successfully in the oil itself and in the air with dropped oil onto the system.

Several fabrication technologies for molecular level ultra-thin films, from organic to organic–inorganic hybrids, are introduced using the surface imaging technology of scanning probe microscopy (S...

We evaluated the dispersion and diffusion of fluorescent-labeled lipophilic vitamin E (VE) in microemulsions (MEs) including water-in-oil (W/O) type ME, oil-in-water (O/W) type ME, and bicontinuous ME (BME), using fluorescence correlation spectroscopy (FCS). We prepared a fluorescent ATTO 488 or BODIPY group labeled VE (VE-ATTO or VE-BODIPY). VE-ATTO possesses lipophilic and hydrophilic parts, while VE-BODIPY consists solely of the lipophilic part. The VE-ATTO dissolved in heptane solution as an oil phase appeared hot pink in color due to the solvatochromism effect under room light and almost no fluorescent signal, which was unlike the VE-ATTO dissolved in ME solutions and all the VE-BODIPY solutions (typical fluorescent green color). The FCS measurement proved that VE-BODIPY diffuses faster than VE-ATTO. This is presumably because the "surfactant-like" VE-ATTO is localized and trapped at the micro-water/micro-oil interface of the MEs, while the VE-BODIPY exists in the ME phase and macro-oil phase with good dispersion. These results demonstrate that FCS is a powerful tool for the rapid evaluation of the lipophilic probe behavior in heterogeneous ME solutions.

We studied the diffusion properties of lipophilic vitamin E (VE) through bicontinuous microemulsions (BME) using both electrochemical and fluorescence correlation spectroscopy (FCS) measurements. We investigated the effect of different composition ratios of micro-water and micro-oil phases in BMEs (W/OBME). When we employed the BME with a lower W/OBME value of 40/60 (oil-rich BME) as an electrolyte solution, we obtained a larger current response from VE at a fluorinated nanocarbon film electrode. Further voltammetric studies revealed that a higher VE diffusion coefficient was observed in the oil-rich BME. The FCS results also exhibited faster diffusion through the oil-rich BME, which played a significant role in accelerating the VE diffusion probably due to the widening of the micro-oil phase pathway in the BME. Moreover, the effect of increasing the VE diffusion was pronounced at the interface between the electrode surface and the BME solution. These results indicate that controlling the conditions of the BME as the measurement electrolyte is very effective for achieving superior electrochemical measurements in a BME.

Fabrication of a two-dimensional covalent network of honeycomb nanosheets comprising small 1,3,5-triamino benzene and benzene-1,3,5-tricarboxaldehyde aromatic building blocks was conducted on Au(111) in a pH-controlled aqueous solution. In situ scanning tunneling microscopy revealed a large defect-free and homogeneous honeycomb π-conjugated nanosheet at the Au(111)/liquid interface. An electrochemical potential dependence indicated that the nanosheets were the result of thermodynamic self-assembly based not only on the reaction equilibrium but also on the adsorption (partition) equilibrium, which was controlled by the building block surface coverage as a function of electrode potential.

We propose a single crystallization and transfer technique of organic semiconductors using a hydrogel capillary (gel capillary crystallization method). Single crystals of the C8-BTBT thienoacene-ba...

Janus nanosheets were prepared from K4Nb6O17·3H2O by modifying surfaces of their two distinct interlayers in a regioselective and sequential manner and subsequent exfoliation. The surface properties of nanosheets were investigated by phase atomic force microscopy imaging and two types of surfaces were discriminated, indicating that Janus nanosheets were successfully prepared.

Necklace-shaped dimethylsiloxane (DMS) polymers bearing polyhedral oligomeric silsesquioxane (POSS) cages with “alternating modulated chain” arrangements were synthesized, by the polycondensation of a dimeric POSS precursor and dimethyl oligo-siloxane dichloride. Films of POSS-DMS polymers with “alternating modulated chain” arrangements were highly transparent. This observation is consistent with amorphous structures. Along with “constant chain” and “random chain” type polymers, three different chain arrangements of necklace-shaped polymers can now be produced. The physical properties of the three polymer types with constant POSS cage contents were compared. “Alternating modulated chain” type polymers had lower glass transition temperatures than the other two polymer types. This was attributed to the cooperative relaxation of long chain moieties that comprised half of the connecting chains. “Alternating modulated chain” type POSS-DMS polymers with average chain lengths of three to four exhibited heat resistances of over 470 °C in air.

The transport of small gases (H2, CO2, N2, O2) through a series of novel membranes based on necklace-shaped inorganic polymers (DMS@POSS), in which a polyhedral oligomeric silsesquioxane (POSS) cage unit and soft chains of oligo-dimethyl siloxane (DMS) were alternately connected, was investigated. The influence of the DMS chain length and crosslinking density of the DMS@POSS on membrane properties were studied. The membranes revealed characteristic structure-property relation towards both glass transition and gases transport. Specifically, clear dependence of properties from the length of DMS units (or overall siloxane content) was revealed. Gas transport properties, when compared to state-of-art polydimethylsiloxane and commercial silicone rubber, demonstrated significantly higher selectivity of DMS@POSS for carbon dioxide (in CO2/N2), hydrogen (in H2/N2) and oxygen (in O2/N2) but lowered permeability, proportional to the amount of POSS in the material. With a precise control over mechanical and thermal properties compared to conventional silicone rubbers, described materials could be considered as materials of choice in niche gas separation or other applications.

Natural polysaccharides represent a renewable resource whose effective utilization is of increasing importance. Chemical modification is a powerful tool to transform them into processable materials but usually sacrifices the original structures and properties of value. Here we introduce a chemical modification of Curdlan, a β-1,3-glucan, via 4,6-acetalization. This modification has successfully combined a helix-forming ability of Curdlan with new solubility in organic media. Furthermore, it has operationalized efficient cohelical crossovers (CCs) among the helices to demonstrate the formation of an extensive supramolecular network that goes well beyond the nanoscopic regime, allowing for preparation of flexible self-supporting films with macroscopic dimensions. This protocol, which is now viewed as supramolecular polymerization of a helical polysaccharide macromer, can add a new dimension to "polysaccharide nanotechnology", opening a door for the creation of unconventional polymer materials based on the cohelical crossover network (CCN).

Bicontinuous microemulsions (BMEs, Winsor III), also called middle-phase microemulsions, are low-viscosity, isotropic, thermodynamically stable, and spontaneously formed mixtures of water, oil, and surfactants. They are unique solution media for electrochemistry. Here, we introduce the recent progress in the electrochemistry of BMEs from their fundamental aspects to their practical applications. Electrochemistry using BMEs has two irreplaceable properties: the coexistence of hydrophilic and lipophilic species with high self-diffusion coefficients; and the dynamic deformation of structures at an oil/water/electrode ternary interface, which is easily changed according to the property of the electrode surface. Electrochemical contact with the micro-saline and oil phases in a BME is alternately or simultaneously achieved by controlling the hydrophilicity and lipophilicity of the electrode surfaces. The selective electrochemical analysis of hydrophilic and lipophilic antioxidants in liquid foods without extraction demonstrated as the use of the unique ternary solution structures of BME on solid surfaces.

Two-dimensional self-assembly of melem at pH-controlled aqueous solution-Au(111) interfaces has been investigated by electrochemical scanning tunneling microscopy. In the solutions with pH>pK b1 of melem, two ordered self-assembled structures (honeycomb and close-packed structures) and one disordered fibrillar structure were observed as a function of the surface coverage of melem controlled by the electrode potential. In contrast, in the acidic solution with pH

In the present study, we demonstrated a new concept for the direct electrochemical hydrogenation of toluene using an acidic microemulsion electrolyte with active Pt electrodes to pave the way for efficient methylcyclohexane mass production. We have achieved a Faradaic efficiency of 80% for the toluene/methylcyclohexane conversion at a Pt black electrode, under galvanostatic conditions and in a one-compartment cell. The reaction rate and selectivity of the toluene reduction were found to depend strongly on the surface structure of the Pt electrodes. Keywords: Organic hydride, Hydrogenation, Microemulsion, Pt electrode, Surface-sensitive reaction, Hydrogenolysis

Electrochemical deposition has been the preferred method to use for the soft templating of nanoporous metal thin film because of its low-temperature metallization processes, which prevent damage to the structures not only of soft templates, including self-assembled surfactants or copolymers, but also of the formed nanoporous metals. Recently developed soft-templating methods are based on the replication of highly ordered micelle assemblies composed of surfactants or copolymers. However, it is still difficult to achieve wide size control over 100 nanometers by soft templating, though such control is necessary for electrocatalytic or biosensing applications. We report on the fabrication of monolithic nanoporous gold (Au) thin films by electrodeposition in bicontinuous microemulsion (BME) as a dynamic soft template (Figure (a)). Au electrodeposition occurs only at the aqueous phase of BME, which has intertwined nanometer-ordered three-dimensional networks composed of aqueous and oil solution channels compartmentalized by surfactants and cosurfactants. The thermodynamically stable BME can be formed simply by “mixing” together of the components, and the solution/solution structure of BME could be controlled simply by changing the BME composition. We prepared three kinds of BME solutions, including water-rich BME (water/oil ratio: 66/34), oil-rich BME (33/67), and equally mixed BME (69/31), by mixing 5.00 mL of 1 M hydrochloric acid solution containing 50 mM tetrachloroaurate(III), 5.00 mL cyclohexane, 0.40 g sodium dodecyl sulfate (SDS), and different volumes of 2-methyl-2-butanol (470, 590, and 510 μL, respectively) as cosurfactants. Figure (b-d’) shows the top surface and cross-sectional FE-SEM images of the resultant gold thin film electrodeposited onto sputtered Au film at -0.30 V vs. Ag/AgCl for 300 sec in (a) oil-rich BME, (b) equally mixed BME, and (c) water-rich BME, respectively. The resultant Au films each had a unique monolithic nanostructure grown vertically to the electrode surface. The characteristic ligament diameters of these films increased from 40 to 200 nm as the aqueous solution content increased. These results clearly indicate that BME no doubt behaved as a soft template and successfully demonstrate that structural control can be easily achieved by changing the BME solution/solution structure. In the case of equally mixed BME, we also confirmed that the ligament axial length was controllable between 180 and 650 nm by changing the electrodeposition time from 200 to 400 s. The cross-sectional observation of all the films revealed that there were no side pores even though BME had a reticulated solution structure on the order of 100 nm or less. This indicates that monolithic BME structures changed continuously during electrodeposition depending on the film surface morphology and acted as dynamic soft templates. We conducted voltammetric experiments to assess surface characteristics such as electrochemically active surface area (ECSA), exposed facets, and electrocatalytic activity. The apparent electrode area of each Au film was defined by putting insulating tape with a 2-mm-diameter hole on the electrode surface. The linear sweep voltammetry after forming a fully oxidized surface in 0.5 M H2SO4 solution revealed that the ECSA of the monolithic nanoporous Au film electrodeposited in equally mixed BME for 300 s was 4.2 times greater than that with the sputtered Au film (before electrodeposition). The cyclic voltammetry in the same solution revealed that the oxidation potential of the main peak current of the monolithic nanoporous Au thin film was lower (+1.08 V vs. Ag/AgCl) than that of sputtered Au thin film (1.29 V). These results indicate that the existence of well-exposed {100} facets and/or dominant step/kink sites at the monolithic nanoporous Au thin film probably derived from vertically grown, highly curved nanostructures. As a test reaction, the methanol oxidation reaction (MOR) was used to investigate the electrocatalytic performance of electrodeposited nanoporous Au films. The cyclic voltammetry obtained in the 0.5 M KOH aqueous solution in the absence and presence of 1 M methanol resulted in a 1.9 times larger peak top current (446 μA cm-2 app) at the monolithic nanoporous Au film than that of sputtered Au film due to high ECSA. Interestingly, the onset potential of MOR at the monolithic nanoporous Au film was -0.58 V, which is 0.20 V more negative than that at the sputtered Au film; this might derive from the {100} facets and/or the step/kink structure of the nanoporous Au film. Figure 1

A series of necklace-shaped alternating siloxane copolymers that consisted of a bifunctional polyhedral oligomeric silsesquioxane (POSS) cage and flexible linear dimethyloligosiloxane (DMS) chain segment have been synthesized from bifunctional POSS molecules by two different synthetic methodologies, polycon-densation and ring-opening polymerization. Necklace-shaped POSS-DMS polymers with three different chain arrangements, “constant chain,” “random chain,” and “alternating modulated chain,” have been synthesized. The necklace-shaped POSS-DMS polymers gave transparent thermoplastic and thermosetting plastics with high heat resistance upon cross-linking at the end of the polymers. The controllable structural diversity of these polymers allows control of their physical properties such as flexibility and glass transition temperature. These necklace-shaped polymers consisting of bulky functional inorganic units and alternately connected short soft chains will pave the way to inorganic soft materials, which are novel inorganic materials that can be handled like an organic polymer possessing solubility, plasticity, or entropic elasticity.

Two-wavelength infrared responsive soft actuators composed of rare-earth-oxide particles composited in a thermoresponsive hydrogel have been constructed. Because Nd2O3 and Yb2O3 particles possess independent narrow infrared adsorption at 808 and 980 nm, respectively, the vicinity of the particles in the gel can be individually heated by irradiation at each adsorption wavelength, inducing a local volume phase transition. The wavelength-selective volume phase transition can be controlled based on the combination of the particles incorporated in the gels and the wavelength of the irradiation laser at the optimized water temperature. Only the alternatively correct combinations successfully induced selective local clouding at the irradiation spots in the gel sheets. The original transparency of the gel was immediately recovered by turning off the light. Furthermore, rod-shaped block gels with Nd2O3 and Yb2O3 particles separately arranged on the left and right sides at the bottom of the rods were prepared to demonstrate wavelength-selective bending motion. The correct light combination caused reversible bending motion of only the side of the rod gel with the corresponding adsorbed particles.

Janus nanosheets were prepared from K4Nb6O17·3H2O by modifying surfaces of their two distinct interlayers in a regioselective and sequential manner and subsequent exfoliation. The surface properties of nanosheets were investigated by phase atomic force microscopy imaging and two types of surfaces were discriminated, indicating that Janus nanosheets were successfully prepared.

Large two-dimensional (2D) nanosheets of crystalline coordination frameworks were prepared on highly oriented pyrolytic graphite (HOPG) by re-crystallization induced by thermal equilibrium treatment in acetic acid vapor. The nanosheets comprised 5,10,15,20-tetrakis(4-carboxyphenyl)-porphyrin (H2TCPP) cross-linked by copper ions. We found that an acetic acid vapor environment dramatically decreased the activation energy and accelerated the recombination of coordination bonds between metal ions and carboxylate ligands in the H2TCPP-Cu frameworks. Ultimately, two-dimensional horizontal crystal growth was induced to form monomolecular sheets as the most thermodynamically stable crystal structure on a well-defined surface.

The temperature and concentration dependencies of the crystallization of two small-molecular semiconductors were clarified by constructing quasi-phase diagrams at air/oil interfaces and in bulk oil phases. A quinoidal quaterthiophene derivative with four alkyl chains (QQT(CN)4) in 1,1,2,2-tetrachroloethane (TCE) and a thienoacene derivative with two alkyl chains (C8-BTBT) in o-dichlorobenzene were used. The apparent crystal nucleation temperature (Tn) and dissolution temperature (Td) of the molecules were determined based on optical microscopy examination in closed glass capillaries and open dishes during slow cooling and heating processes, respectively. Tn and Td were considered estimates of the critical temperatures for nuclear formation and crystal growth, respectively. The Tn values of QQT(CN)4 and C8-BTBT at the air/oil interfaces were higher than those in the bulk oil phases, whereas the Td values at the air/oil interfaces were almost the same as those in the bulk oil phases. These Gibbs adsorption ...

Two-dimensional supramolecular covalent macromolecular architectures were visualized directly by in-situ scanning tunneling microcopy and colorful π-conjugated nanofilms with unique mesostructures formed spontaneously on hydrophobic substrates from aqueous solutions in the presence of simple aromatic building block molecules under ambient conditions. We thus report the results of surface-mediated polycondensation and chemical liquid deposition. The Schiff base coupling reaction applied for this soft solution process is a dynamic reversible covalent coupling reaction that can be managed by careful changes in solution conditions based on ‘adsorption’ and ‘polymerization’ equilibria. This low-cost and eco-friendly ‘bottom-up’ method allows great diversity in terms of the design of primary polymeric chemical structures by the selection of building blocks without the need to consider the solubility of the polymer. This paves the way to a true ‘bottom-up’ assembly of a vast array of solid-supported, designer supramolecular nanoarchitectures with potential use as functional materials for next-generation organic electronics.

We used in situ scanning tunneling microscopy to investigate the formation of two-dimensional supramolecules by means of reversible azomethine condensation reactions between aqueous 5,10,15,20-tetrakis(4-aminophenyl)porphyrin (TAPP) and terephthaldicarboxaldehyde (TPA) or benzaldehyde (BA) at the solid/liquid interface of an iodine-modified Au(1 1 1) surface. A nanomesh and a close-packed array were formed by the reaction of TAPP with the dicarboxaldehyde. Formation of these structures was driven by Schiff base (azomethine) bonding and simultaneous self-assembly controlled by adsorption and condensation equilibria. Surface cross coupling between TAPP and the monocarboxaldehyde (BA) formed highly ordered adlayers consisting solely of TAPP symmetrically disubstituted with two BA molecules attached at diagonally opposite corners. The position selectivity was achieved through simultaneous coupling reaction equilibria and the thermodynamic self-assembly.

Different bicomponent self-assembled structures comprising melamine and melem were formed at aqueous solution–Au(111) interfaces by varying the concentrations of melamine and melem and the electrochemical potential. The structures were observed by in situ scanning tunneling microscopy. The structures of the bicomponent networks were controlled thermodynamically through the surface concentration and the molecular ratio. Interestingly, the solution concentration did not directly reflect the surface density of the self-assembled structures because of the flocculation-like behavior around the interface. Furthermore, structural phase transitions between the melem monocomponent honeycomb network, the bicomponent honeycomb network, and the melamine monocomponent honeycomb network with aggregates were directly and reversibly observed by controlling the electrochemical potential.

The fluorescence intensities for various vibronic fine structures in the 1-pyrenecarboxaldehyde (PyCHO) fluorescence show strong environment dependence. In aqueous solvent, the distribution of dye is highly depended on its concentration labels and varies from excimer to monomeric state. UV-Vis Spectroscopic analysis could not able to detect dye below 10-7M concentration, whereas a new monomeric peak at 342 nm was observed after heating and cooling treatment at above the concentration. At 10-8M concentration, only monomeric distribution of 1-PyCHO reveals a strong temperature (20-50 °C) induced reversible perturbation of the vibronic band intensities. This suggests the operation of some specific solute-solvent dipole-dipole interaction mechanism strongly influenced by heating.

The continuous epitaxial growth of vertically standing nanowalls of aromatic poly(azomethine), which consisted of hydroxyl-substituted aromatic dialdehydes and several aromatic diamines as building blocks, was achieved on a graphite substrate, using chemical liquid deposition in aqueous media. The vertical growth of poly(azomethine) nanowalls (ANWs) occurred on a graphite sheet, and they were arranged with a rotational angle of 60° relative to each other. Spontaneous “on-site” polycondensation selectively progressed on the top edges of the walls, rather than the flat surfaces or bottoms of walls. The formation of the standing ANWs was likely due to limited supply of monomers in the solution, and the strong intermolecular π–π stacking. In addition, fluorescent/nonfluorescent ANWs were arbitrarily designed by selecting nonconjugated or conjugated aromatic diamines, respectively.

Atom transfer radical polymerization (ATRP) was employed to synthesize novel polymer particles. The surface of porous polymeric cellulose beads was modified by sodium hydroxide, 2-chloromethyloxirane, ethylenediamine and 2-bromo-2-methylpropionyl bromide successively in order to activate the beads surface so that it can play an important role as an initiator for ATRP reaction. ATRP on the modified cellulose beads surface was carried out with styrene and sodium p-styrenesulphonate monomers in the presence of non aqueous and aqueous phases respectively. The polymer products on the substrate surface were characterized by elemental analysis (EA), attenuated total reflectance-infrared (ATR-IR) spectroscopy and carbon13 – nuclear magnetic resonance (13C-NMR).

Diblock copolymers consisting of methylmethacrylate (MMA) and N-hydroxyethylacrylamide (HEAAm) polymer were successfully synthesized via direct two steps atom transfer radical polymerization (ATRP). At first, poly(methylmethacrylate) (PMMA) macroinitiators were prepared using methyl 4-(bromo-methyl) benzoate initiator and were used for synthesizing PMMA-b-PHEAAm block copolymers. PMMA homopolymers were synthesized in N,N′-dimethylformamide (DMF) using CuBr/2, 2′bipyridine catalyst system at 110 °C temperature in nitrogen atmosphere. Block copolymers were synthesized in mixture of DMF/water (8/2 v/v%) and in pure DMF in the presence of CuBr/1,1,4,7,10,10-hexamethyltriethylenetetramine (HMTETA) catalyst system at 85 and 100 °C, respectively, while argon was used for deoxygenation and inert environment. Purification of block copolymers was conducted through dialysis against deionized water using a dialysis tubing (MWCO 3,500, cellulose membrane). Molecular weights of PMMA polymers (M n = 4,400, 6,200 and 8,400 Da) were determined by size exclusion chromatography using tetrahydrofuran (THF) as eluent. The chemical structure and actual copolymer compositions were determined using elemental analysis (EA), attenuated total reflectance infrared (ATR-IR) and proton nuclear magnetic resonance (1H NMR) spectroscopic analysis. Phase separation of diblock copolymers resulting in two glass transition temperatures as detected by differential scanning calorimeter (DSC) proves their amphiphilic behavior. Thermogravimetric analysis (TGA) also showed that diblock copolymer, with two-step decomposition has higher thermal stability than PMMA.

Cu(I)-catalyzed Huisgen click reactions between lipophilic polymer (tri-arm azidofunctionalized polystyrene) and hydrophilic polymer (copolymer of styrene sulfonate sodium and propargyl methacrylate) were investigated and hollow capsules, consisting of composite polymer nanofilms were obtained in chloroform-water biphasic solution. Since the lipophilic polymer, or hydrophilic polymer and copper catalyst were present in the oil or aqueous phase, respectively, the cross-linking reaction proceeded only at the phase interface. The combination of lipophilic and hydrophilic polymers produced hollow capsules consisting of nanofilms with lipophilic core and hydrophilic shell.

To selective adsorption of glucoamylase (GA) from the raw materials of the unpasteurized sake, various polymer beads were prepared by immobilization of cationic or anionic functional groups onto cellulose beads (Cellufine). Under conditions which mimic sake (GA 500 µg mL−1, ethanol 20 vol%, pH 4), Aspergillus species GA (As-GA) (pI 3.5) was strongly adsorbed by cationic Cellufines with anion-exchange capacity (AEC) of 0.5–1.3 meq g−1, but Rhizopus sp. GA (pI 6.5) was strongly adsorbed by anionic adsorbents with cation-exchange capacity of 0.3–1.1 meq g−1. The As-GA selectivity of the cationic Cellufines depended on their apparent pKa (pKa,app) but not necessarily on their AEC. The Cellufine-poly(ethyleneimine) (pKa,app 7.9, AEC 0.4 meq g−1) was effective at adsorbing As-GA (>99%) in a sake model solution (GA 250 µg ml−1, ethanol 20 vol%, 0.016 M acetate buffer, pH 4), but it also adsorbed organic acid, such as acetic acid. By contrast, Cellufine-poly(ϵ-lysine) (pKa,app 7.3–7.4, AEC 0.6–1.0 meq g−1) select...

The widespread use of scanning probe microscopy (SPM) techniques has revolutionized many scientific and industrial fields, especially material science, by allowing the surface morphology to be visualized and the composition or properties of materials to be probed at the atomic or submolecular scale. Here, we review the recent innovations in SPM techniques applied to modern material science, from two-dimensional covalent supramolecular systems based on bottom-up nanotechnology to advanced material development for polymer electrolyte fuel cells and thin film solar. Among the variety of SPM methods, electrochemical scanning tunneling microscopy, atomic force microscopy, conductive atomic force microscopy, and Kelvin probe force microscopy are discussed.

The 2D molecular assemblies of chloride-coordinated mixed-valence diruthenium complexes, each possessing phenyl, naphtyl, or anthracenyl moieties, were examined on an Au(111) at electrochemical interface. In situ scanning tunneling microscopy images revealed a clear dependence of the molecular assembly on both the nature of the aryl functional groups and on the redox state of the dinuclear ruthenium complex, either chloride-coordinated RuII/RuIII or noncoordinated RuII/RuII. At potentials where the RuII/RuIII and RuII/RuII redox states were in equilibrium, two distinct redox states were clearly identified at the single-molecular level. We found that manipulating both the electrochemical potential and the aryl functional group substitution was important for controlling the 2D molecular assembly of a chloride-coordinated diruthenium complex on an Au(111) surface.

The pursuit of methods for design and preparation of robust nanoarchitectonic systems with integrated functionality through bottom-up methodologies remains a driving force in molecular nanotechnology. Through the use of π-conjugated covalent bonds, we demonstrate a general substrate-mediated, soft solution methodology for the preparation of extended π-conjugated polymeric nanoarchitectures in low-dimensions. Based on thermodynamic control over equilibrium polymerization at the solid-liquid interface whereby aromatic building blocks spontaneously and selectively link, close-packed arrays composed of one-dimensional (1-D) aromatic polymers and two-dimensional (2-D) macromolecular frameworks have been prepared and characterized by in situ scanning tunneling microscopy. This methodology eliminates the necessity for severe conditions and sophisticated equipment common to most current fabrication techniques and imparts almost infinite possibilities for the preparation of robust materials with designer molecular architectures.

Static dispersion polymerization of styrene, methyl methacrylate, ethyl methacrylate, butyl methacrylate and benzyl methacrylate, initiated by a lipophilic initiator in an aqueous dispersion with unmodified silica particles was investigated. Polymerization of styrene gave a mixed dispersion of silica and monodisperse polystyrene (PS) particles, which was extremely stable compared with the aqueous dispersion of silica particles. The enhanced dispersion stability is due to a thixotropic effect based on weak attractive interparticle interactions between silica and PS particles in aqueous dispersion. An aggregate in which silica particles are surrounded by the smaller PS particles is formed and inhibits flocculation of silica particles, thus giving enhanced dispersion stability. The results of similar static polymerization reactions with methacrylate analogs indicate that hydrogen bonds between benzene ring and hydroxy groups on the silica surface, and not electrostatic interaction derived from initiator residues, are the origin of weak interaction for thixotropic aggregation.

A simple and useful technique for preparing an oxidation-resistant film on a Pb electrode is reported herein. A Pb electrode was dipped into a mixed solution containing 1% ascorbic acid and 5% boric acid at 40°C and then air-dried. The Pb electrode was coated with a film on its surface to protect it from oxidation. After three months, the oxide layers on the Pb plate were analyzed by treatment with pure ascorbic acid or boric acid. An oxidized layer was not observed on the plate treated with the mixed solution of ascorbic acid and boric acid; this was confirmed using an electron probe micro analyzer (EPMA). To further analyze the effect of co-absorption, the interaction between ascorbic acid and boric acid in solution was evaluated using a UV-visible spectrometer, and mixed solid samples were analyzed using FT-IR spectrometry.

Continuous porous poly(N-isopropylacrylamide) (pNIPAM) gels were prepared by radical polymerization in a bicontinuous microemulsion (BME) consisting of saline and toluene microphases. The BME gels ...