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A hydrotalcite-like film has been successfully deposited on an Al-bearing glass substrate based on an interface reaction between an Al layer and a zinc aqueous solution. The film selectively grew on the Al surface but not on the glass surface. The film on Al was composed of layered nanosheets of a hydrotalcite-like compound containing Al and Zn. Comparably, deposits on the plastic surface and precipitates in solution were wurzite-type ZnO with various morphologies depending upon the preparation conditions. At low supersaturation degrees, single crystals and superstructures of Zn-Al hydrotalcite were also obtained. This porous hydrotalcite film has a potential application as catalyst supports, environmental materials, or matrixes for hydrotalcite-based nanocomposite films. Using Al as a reaction interface makes it easy to coat porous hydrotalcites on a series of matrix materials varying in shapes and properties, which is important for achieving practical applications. In addition, the method developed should be widely applicable to other systems for the preparation of porous or oriented hydrotalcite-like thin films by an appropriate combination of divalent/trivalent solution−substrate systems.

We developed a self-assembly process of silica particles to fabricate desired patterns of colloidal crystals having high feature edge acuity and high regularity. A micropattern of colloidal methanol prepared on a self-assembled monolayer in hexane was used as a mold for particle patterning, and slow dissolution of methanol into hexane caused shrinkage of molds to form micropatterns of close-packed SiO2 particle assemblies. This result is a step toward the realization of nano/micro periodic structures for next-generation photonic devices by a self-assembly process.

Siloxane-anchored, self-assembled monolayers (SAMs) on single crystal Si were prepared with a variety of surface functional groups using a single commercially available surfactant (1-bromo-11-(trichlorosilyl)undecane) followed by in situ transformations. Polar (thioacetate and thiol), nonpolar (methyl), acidic (sulfonic and carboxylic), basic (various amines), and ionic (alkylammonium) surface functionalities were prepared. For primary amine and sulfonate surfaces, the degree of surface charge as a function of pH was determined ex situ using X-ray photoelectron spectroscopy (XPS). Sulfonate SAMs exhibited much higher effective pKa (~2) than dilute sulfonic acid (−5 to −6), and amine SAMs exhibited much lower pKa (~3) than dilute organic amines (~10). This is attributed to the stabilization of nonionized groups by adjacent ionized groups in the SAM. Zeta potentials of these SAMs as a function of pH were consistent with the XPS results and indicated that ionizable SAM surfaces can generate surface potentials much higher than those of nonionic SAMs (thioacetate, methyl) and typical oxide surfaces.

We developed a novel self-assembly process to fabricate an orderly array of particle wires constructed from a close-packed colloidal crystal without preparation of patterned templates. A substrate was immersed vertically into a SiO2 colloidal solution, and the liquid surface moved downward upon evaporation of solution. Particles formed a mono-/multiparticle layer, which was cut by the periodic drop-off of solution. The orderly array of particle wires was successfully fabricated, showing the suitability of the self-assembly process for the fabrication of nano-/microstructures constructed from nano-/microparticles or blocks. The mechanism of the assembly process and control of thickness, width, and interval of particle wires were further discussed. Moreover, an array of particle wires constructed not from close-packed face-centered cubic (or hexagonal close packed) structure but from two kinds of particles was realized to fabricate an array of particle wires with NaCl structure by this self-assembly process.

By grafting (aminopropyl)triethoxysilane (APTES) as the buffer layer on poly(ethylene terephthalate) (PET) surface, the SAMs of octadecyltrichlorosilane (OTS), phenyltrichlorosilane (PTCS), vinyltrichlorosilane (VTCS), and p-tolyltrichlorosilane (TTCS) were fabricated on the flexible polymer substrate. The properties of SAMs were accurately controlled by adjusting the immersing time of substrates in the solutions and the concentration of the solutions. The SAMs acted as templates, and TiO2 micropattern was successfully deposited on OTS, TTCS, and PTCS SAMs.

We report on the photoinduced superhydrophilicity of the surface of amorphous TiO2. Amorphous TiO2 thin films were prepared on self-assembled monolayers by the peroxotitanate-complex deposition (PCD) and liquid-phase deposition (LPD) methods. The surface morphology and topography were characterized in detail. The contact angles were 34° and 66° for the as-deposited thin films through the PCD and LPD methods, respectively, which slowly increased to about 70° and 73° after being stored in air. After irradiation by UV light, the contact angle vanished and the surface exhibited superhydrophilicity. The superhydrophilicity and hydrophobicity could be switched by alternatively exposing the surface to UV light and drying in an atmosphere filled with organic gases. Although the oxidation of the contamination on the surface has effects on the increase in hydrophilicity, the X-ray photoelectron spectroscopy results suggested that the superhydrophilicity was also related to the transformation of the Ti−OH groups to groups that have dangling bonds. This paper indicates that an amorphous TiO2 thin film does not need to be heated to obtain superhydrophilicity; such a self-cleaning surface can be achieved at room temperature by our newly developed environmentally friendly method.

Small-angle X-ray scattering (SAXS) from an organogel system prepared from methyl 4,6-O-benzylidene-α-d-mannopyranoside and p-xylene was carried out with a synchrotron X-ray source at SPring-8, which revealed that hexagonally packed fibrils are formed in the gel state. The spacing between the fibrils can be evaluated to be about 60 Å, and this value was almost independent of both the gelator concentration and the temperature. Furthermore, the spacing is larger than the gelator molecular size. Upon heating, this supramolecular structure completely disappeared. Time-resolved SAXS revealed that phase separation takes place initially and subsequently the hexagonal structure is formed. Wide-angle X-ray diffraction (WAXD) showed that there is no crystalline peak at all and the diffraction pattern is consistent with being amorphous. ¹H NMR spectral data show that the gelator molecules still maintain thermal motion in the gel state. The present SAXS, WAXD, and NMR results contrast with those of “dry gels” in which the gel fibers consist of the crystal of the gelators. Our results suggest that the solvent molecules are incorporated into the gel fiber and the present gel can be classified as a “wet gel”.

This paper presents a novel process for the fabrication of site-selectively deposited tin oxide ultrathin films (<10 nm) by using molecular recognition between the precursors and the surface of the Si substrate. Using this simple technique, the film thickness of micropatterned tin oxide films was easily controlled. Patterned self-assembled monolayers, in which both hydrophilic and hydrophobic areas formed, were used as templates for the site-selective deposition of the films. Two precursors of SnCl4 and C4H9SnCl3 were selected. The films were selectively deposited on the hydrophilic regions through the liquid phase. The growth rate of the film deposited in SnCl4 solution was approximately 6 times faster than that in C4H9SnCl3 solution. A quartz crystal microbalance measurement implied that film growth could be suppressed by the formation of hydrophobic surfaces on the growing films with increasing immersion time in C4H9SnCl3 solution.

The deposition manner of ZnF(OH) on the OH- and phenyl-terminated self-assembled monolayers (SAMs) in Zn−NH4F aqueous solutions has been investigated. NH4F plays a role as a control agent of supersaturation by complex formation in the deposition process of ZnF(OH). ZnF(OH) was deposited as spherical particles on a substrate and decomposed into ZnO by annealing at 300 °C in air. A shorter induction time for heterogeneous nucleation and a larger number density of nuclei of ZnF(OH) were found on the OH−SAM surface, which indicates a lower interfacial energy between ZnF(OH) and the OH−SAM surface. Taking advantage of the effects of the surface functional groups on the deposition manner, ZnO was successfully micropatterned by using photopatterned SAMs as templates.

We propose a technique for fabricating a carbohydrate-terminated monolayer (CM) surface, which is extremely flat at the angstrom level. The CM was immobilized onto a Si surface by Si−C covalent bond. Specific adsorption of the protein molecule from a contacting solution was observed on the CM area of a patterned CM substrate surface, while its nonspecific adsorption was observed on the Si−O area.