Electroless Plating of Organic Thin Films by Reduction of Nonionic Surfactants Containing an Azobenzene Group

Organic-Inorganic Hybrid Nanoparticles via Photoinduced Micellation and Siloxane Core Cross-Linking of Stimuli-Responsive Copolymers

Photoacid-induced siloxane cross-linking of stimuli-responsive copolymer micelles allows the synthesis of well-defined organic-inorganic hybrid nanoparticles. Two conceptually different synthetic approaches are presented, both via photoinduced cross-linking of poly(4-hydroxystyrene-block-styrene) micelles and via one-pot photoacid-catalyzed micelle formation and siloxane cross-linking of poly(4-tert-butoxystyrene-block-styrene). The multistep synthetic route showed intermicellar cross-linking leading to agglomerates. In contrast to this, the formation of the nanoparticles via the one-pot synthesis yielded well-defined structures. The use of different siloxane cross-linking agents and their effects on the properties of the cross-linked micellar structures have been evaluated. Scanning electron microscopy and differential scanning calorimetry indicate rigid core cross-linked nanoparticles. Their size, molar mass, and swelling behavior were analyzed by dynamic and static light scattering. Cyclic siloxane cross-linking agents lead to residual C═C double bonds within the nanoparticle core that allow postsynthetic modification by, e.g., thiol-ene click reactions.

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.

Redox-responsive delivery systems

Stimuli-responsive systems for the transport and delivery of materials to a given location at a specific time are highly valuable in numerous applications. The characteristics of the delivery system are dictated by the requirements of a particular application, which include the nature of the stimulus for actuation of the delivery process. Electron transfer has moved to the forefront as a stimulus for responsive delivery systems, particularly for those used in drug and reagent delivery, and for analyte transport/separation avenues. Interest in redox-activated delivery of materials arises from the abundance of redox-active stimuli that can be used to make delivery occur, the often simple chemical nature of the activation process, and the ease of constructing delivery vehicles with an integrated redox-responsive trigger group. This review is focused on vesicle- and micelle-based vehicles whose contents can be delivered by a redox stimulus due to their potential to meet the needs of key applications.

Photochemical control of molecular assembly formation in a catanionic surfactant system

Photochemical control of vesicle disintegration and reformation in aqueous solution was examined using a mixture of 4-butylazobenzene-4'-(oxyethyl)trimethylammonium bromide (AZTMA) as the photoresponsive cationic surfactant and sodium dodecylbenzenesulfonate (SDBS) as the anionic surfactant. Spontaneous vesicle formation was found in a wide-ranging composition of the trans-AZTMA/SDBS system. AZTMA molecules constituting vesicles underwent reversible trans-cis photoisomerization when irradiated with ultraviolet and visible light. Transmission electron microscopy observations using the freeze-fracture technique (FF-TEM) showed that UV light irradiation caused the vesicles to disintegrate into coarse aggregates and visible light irradiation stimulated the reformation of vesicles (normal control). A detailed investigation of the phase state and the effects of UV and visible light irradiation on the AZTMA/SDBS system with the use of electroconductivity, dynamic/static light scattering, and surface tension measurements and FF-TEM observations revealed that in the AZTMA-rich composition (AZTMA/SDBS 9:1) a micellar solution before light irradiation became a vesicular solution after UV light irradiation and visible light irradiation allowed the return to a micellar solution (reverse control). Thus, we could photochemically control the disintegration (normal control) and reformation (reverse control) of vesicles in the same system.

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.

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.

Self-assembly of light-sensitive surfactants

This review covers recent advances with an intriguing class of functionalised light-sensitive surfactants. The main chemical classes are described, and the photo-responses in interfacial and aggregation systems are discussed.