Controlling surface energy of glass substrates to prepare superhydrophobic and transparent films from silica nanoparticle suspensions.

We fabricated superhydrophobic and transparent silica nanoparticle (SNP) films on glass plates via spray-coating technique. When suspensions containing 1-propanol and hydrophobic SNPs were sprayed over glass plates that were modified with dodecyl groups, superhydrophobic and transparent SNP films were formed on the substrates. Surface energy of the glass plates had a significant role to obtain superhydrophobic and transparent SNP films. SNP films did not show superhydrophobicity when bare glass plates were used as substrates, because water droplets tend to adhere the exposed part of the hydrophilic glass plate. Glass plates having extreme low surface energy were not also suitable because suspension solution was repelled from the substrates, which resulted in forming non-uniform SNP films.

Microcontact printing for patterning carbon nanotube/polymer composite films with electrical conductivity.

Patterned carbon nanotube (CNT)/acrylic resin composite films were prepared using microcontact printing (µCP). To prepare ink for µCP, CNTs were dispersed into propylene glycol monomethyl ether acetate (PGMEA) solution in which acrylic resin and a commercially available dispersant (Disperbyk-2001) dissolved. The resulting ink were spin-coated onto poly(dimethylsiloxane) (PDMS) stamps. By drying solvent components from the ink, CNT/polymer composite films were prepared over PDMS stamps. Contact between the stamps and glass substrates provided CNT/polymer composite patternings on the substrates. The transfer behavior of the CNT/polymer composite films depended on the thermal-treatment temperature during µCP; thermal treatment at temperatures near the glass-transition temperature (T(g)) of the acrylic resin was effective to form uniform patternings on substrates. Moreover, contact area between polymer and substrates also affect the transfer behavior. The CNT/polymer composite films showed high electrical conductivity, despite the nonconductivity of polymer components, because CNTs in the films were interconnected. The electrical conductivity of the composite films increased as CNT content in the film became higher; as a result, the composite patternings showed almost as high electrical conductivity as previously reported CNT/polymer bulk composites.

Simple method for preparing superhydrophobic paper: spray-deposited hydrophobic silica nanoparticle coatings exhibit high water-repellency and transparency.

Superhydrophobic and transparent coatings are deposited onto paper by spraying alcohol suspensions of SiO(2) nanoparticles. Superhydrophobicity depends on the aggregation states of nanoparticles, which are determined by the type of alcohol used in the suspensions. The superhydrophobicity of the paper is maintained after touching the paper with a bare finger.

Hard and glossy-colored films composed of micropatterned organic dots and electrodeposited honeycomb-shaped nickel walls.

This paper proposes a novel approach for the preparation of colored films with a metallic luster and high hardness. The colored organic films were patterned as microdots by photolithography, and then honeycomb-shaped Ni walls were electrodeposited between the micropatterning. The organic/inorganic composite films showed the hardest grade in a pencil hardness test and high durability in wear resistance tests because the honeycomb-shaped Ni walls protected the colored organic dots.

Facile fabrication of colored superhydrophobic coatings by spraying a pigment nanoparticle suspension.

Superhydrophobic coatings were prepared by spraying a pigment nanoparticle suspension. By changing the type of pigment nanoparticles, the colors of the coating could be controlled. The particle size of the pigments, which determines the surface structure of the coatings, played an important role in exhibiting superhydrophobicity. The spray-coating process is applicable to a variety of materials (e.g., copper, glass, paper, coiled wire, and tied thread), and the superhydrophobicity was repairable.

One-step electrophoretic deposition for the preparation of superhydrophobic silica particle/trimethylsiloxysilicate composite coatings.

SiO(2) particle/silicone resin (trimethylsiloxysilicate (TMSS)) composite coatings were prepared by electrophoretic deposition (EPD), and their wettability was examined. SiO(2) coatings prepared by EPD baths without TMSS were hydrophilic, while superhydrophobicity was observed for SiO(2)/TMSS composite coatings. IR spectra and EDS analyses revealed that not only SiO(2) particles but also TMSS electrophoretically moved toward a cathode; as a result, hydrophilic SiO(2) particles turned into superhydrophobic composite coatings by one-step EPD. SEM and AFM images of the superhydrophobic SiO(2)/TMSS composite coatings showed the presence of both nanometer- and micrometer-sized roughness in their surfaces. Particle size of SiO(2) had a great influence on the wettability of the composite coatings. The superhydrophobic SiO(2)/TMSS composite coatings showed excellent water repellency; they repelled running water continuously. In addition, by controlling the amount of deposited SiO(2) particles and TMSS, transparent superhydrophobic SiO(2)/TMSS composite coatings were prepared.

Method for patterning various nanomaterials: electrochemical deposition of patterned Ni thin films and their utilization as a strippable mask.

We report an interesting approach for preparing micropatternings of nanomaterials, such as carbon nanotubes and TiO(2) nanoparticles. In the method, exfoliation of electrodeposited Ni thin films was the key process. After patterning indium thin oxide (ITO) plates with an insulating photoresist by conventional photolithography, Ni was electrodeposited on only the exposed ITO areas. The resulting substrates were evenly covered with nanomaterials by a drop cast method. By exfoliating the electrodeposited Ni thin films from the substrates, patterned nanomaterial films were formed.

Electrophoretic deposition of phthalocyanine in organic solutions containing trifluoroacetic acid.

The absorption spectra of copper phthalocyanine (CuPc) 1,2-dichloroethane (DCE) solutions containing trifluoroacetic acid (TFAA) shows that the number of protons coordinating to the CuPc molecule was 1 and 2 for the first and second proton adducts, respectively, which indicates the formations of CuPcH(+) and CuPcH(2)(2+). This CuPc molecule may act as a catalyst to dissociate TFAA into trifluoroacetate anion (A(-)) and H(+) and form the proton adducts. The electrical conductivity dependence of the solution on CuPc concentration also supports this mechanism. A dense film of CuPc was deposited on an indium tin oxide cathode plate by electrophoresis of the solution. Similar dense films of a wide variety of phthalocyanines (MPc; M = Cu, H(2), Fe, Ni, Zn, Pb, VO) were also deposited using this method. Similar films of CuPc were also formed using dichloromethane (DCM) and 1,1,1-trichloroethane (TCE) in place of DCE. Depositions are ascribed to the migration of positively charged monomers (i.e., protonated MPc). Scanning electron microscopy revealed that these films are composed of fibrous crystallites, size of which was found to increase with the electrophoresis time, the strength of the applied electrical field and the concentration of CuPc in the bath. The influence of the dielectric constant of the organic solvent on the film growth is discussed.

Synthesis of super hard Ni-B/diamond composite coatings by wet processes.

Ni-B/diamond composite coatings were prepared using electrophoretic deposition and electroless deposition methods, leading to extremely high hardness which is comparable to hard coatings prepared by dry processes.

Organic thin film formation using asymmetric surface-active viologens.

In the present study, asymmetric surface-active viologens were applied successfully for the thin film formation of organic pigments using the immersion plating technique. The influences of the hydrophobicity of the surfactants and the pH of the plating solution on the film formation were investigated. In addition, the interfacial chemistry and electrochemistry of the surfactants were studied, and the mechanism of the film formation has been proposed and discussed.

Bulk heterojunction photoelectrochemical cells consisting of oxotitanyl phthalocyanine nanoporous films and I(3)(-)/I(-) redox couple.

Photoelectrochemical cells based on oxotitanylphthalocyanine (TiOPc) films and an I(3)(-)/I(-) redox couple have been constructed. The TiOPc films were prepared on an indium-tin oxide coated glass plate (ITO) by the micellar disruption method and characterized by their unique nanoporous structure. A photocurrent action spectrum for input radiation directed through the ITO/TiOPc film, film-thickness dependence, and morphological investigation revealed that the cells consisted of a bulk heterojunction formed between the nanoporous TiOPc films and the liquid I3-/I- electrolyte, resulting in a larger short-circuit current (J(sc)= 2.1 mA/cm(2)), open-circuit voltage (V(oc)= 0.11 V), fill factor (ff= 0.31), and hence a larger energy conversion efficiency (eta= 0.13% for an incident white-light intensity of 53 mW/cm2) than the bilayer structure composed of the vaccum-evaporated TiOPc compact film and the I(3)(-)/I(-) electrolyte (J(sc)= 0.16 mA/cm(2), V(oc)= 0.018 V, ff = 0.27, and eta = (1.5 x 10(-3)%).