pH-Responsive Ultrathin Nanoporous SiO Films for Selective Ion Permeation.

Ultrathin nanoporous (NP) films are an emerging field for selective and effective ion/molecular separation and electrochemical sensing applications. We describe selective ion permeation in surface-functionalized ultrathin NP SiO films (NP SiO-NH). The ultrathin NP SiO films with .

Synthesis of metallo-supramolecular materials based on terpyridine functionalized double-decker silsesquioxane with improved complexation efficiency.

Silsesquioxane-based transition-metal complexes have come to the forefront due to the ability of silsesquioxane to control nanostructures and properties. However, some difficulties in complete complexation and purification limit the widespread use of transition-metal-based supramolecular coordination complexes comprising silsesquioxane. Herein, 2 different approaches have been proposed for the synthesis of metallo-supramolecular materials on the basis of ruthenium(II)-terpyridine functional double-layer silsesquioxane (DDSQ) (Tpy/Ru-DDSQ) (Routes 1 and 2).

Titania Nanofilms from Titanium Complex-Containing Polymer Langmuir-Blodgett Films.

This paper proposes a method of fabricating low-dimensional TiO nanofilms at room temperature under ambient pressure conditions. The titanium-containing polymer complex Ti-p(DDA/acac) was synthesized by reacting an amphiphilic copolymer (p(DDA/acac)) with a titanium complex. Its ultrathin films were prepared using the Langmuir-Blodgett (LB) technique.

Cellulose Nanofiber Nanosheet Multilayers by the Langmuir-Blodgett Technique.

We describe a systematic approach for producing cellulose nanofiber (CNF) nanosheets using the Langmuir-Blodgett (LB) technique. The CNFs were obtained from sulfuric acid hydrolysis of commercially available microfibrillated cellulose. Needle-like CNFs, negatively charged by grafted sulfate groups, were maintained at the air-water interface, assisted by amphiphilic polymer, poly( N-dodecyl acrylamide) (pDDA).

Biomimetic Polyelectrolytes Based on Polymer Nanosheet Films and Their Proton Conduction Mechanism.

We report a biomimetic polyelectrolyte based on amphiphilic polymer nanosheet multilayer films. Copolymers of poly( N-dodecylacrylamide- co-vinylphosphonic acid) [p(DDA/VPA)] form a uniform monolayer at the air-water interface. By depositing such monolayers onto solid substrates using the Langmuir-Blodgett (LB) method, multilayer lamellae films with a structure similar to a bilayer membrane were fabricated.

High-Density and Monolayer-Level Integration of π-Conjugated Units: Amphiphilic Carbazole Homopolymer Langmuir-Blodgett Films.

Precise integration of π-conjugated units is a key issue to achieve molecular (nano) electronic devices based on organic semiconductor materials. We specifically examine the Langmuir-Blodgett technique, which allows high-density integration of π-conjugated units. In this study, we designed a carbazole containing acrylamide-based homopolymer [poly(9-ethyl-3-carbazolyl acrylamide) (pCzAA)], in which the π-conjugated unit is connected with a hydrophilic amide unit directly as a side chain.

Synthesis and Porous SiO Nanofilm Formation of the Silsesquioxane-Containing Amphiphilic Block Copolymer.

We describe the synthesis, Langmuir-Blodgett (LB) film formation, and photo-oxidation of an organic-inorganic hybrid block copolymer consisting of N-dodecyl acrylamide (DDA) and silsesquioxane (SQ) comonomers [p(DDA/SQ26)- b-pDDA]. The copolymer was synthesized by reversible addition fragmentation chain transfer polymerization of DDA and SQ. Higher monolayer stability at the air-water interface was confirmed for p(DDA/SQ26)- b-pDDA.

Resistive switching of organic-inorganic hybrid devices of conductive polymer and permeable ultra-thin SiO films.

We propose a resistive switching device composed of conductive polymer (PEDOT:PSS) and SiO ultra-thin films. The SiO film was fabricated from silsesquioxane polymer nanosheets as a resistive switching layer. Devices with metal (Ag or Au)∣SiO∣PEDOT:PSS architecture show good resistive switching performance with set-reset voltages as low as several hundred millivolts.

Resistive non-volatile memories fabricated with poly(vinylidene fluoride)/poly(thiophene) blend nanosheets.

Ferroelectric poly(vinylidene fluoride)/semiconductive polythiophene (P3CPenT) blend monolayers were developed at varying blend ratios using the Langmuir-Blodgett technique. The multilayered blend nanosheets show much improved surface roughness that is more applicable for electronics applications than spin-cast films. Because of the precisely controllable bottom-up construction, semiconductive P3CPenT were well dispersed into the ferroelectric PVDF matrix.

Synthesis and photochemical response of Ru(ii)-coordinated double-decker silsesquioxane.

A double-decker silsesquioxane based bis(terpyridine) ruthenium(ii) complex (2Tpy/Ru-DDSQ), a member of the polyhedral oligomeric silsesquioxane (POSS) class, has been synthesized. Its structure has been characterized using comprehensive techniques such as nuclear magnetic resonance (H NMR) spectroscopy, X-ray photoelectron spectroscopy (XPS), and UV-visible spectroscopy. This work not only deals with the synthesis of 2Tpy/Ru-DDSQ but also provides the first comprehensive investigation based on the photoluminescence and electrochemical features of a POSS member.

Acid-Group-Content-Dependent Proton Conductivity Mechanisms at the Interlayer of Poly(N-dodecylacrylamide-co-acrylic acid) Copolymer Multilayer Nanosheet Films.

The effect of the content of acid groups on the proton conductivity at the interlayer of polymer-nanosheet assemblies was investigated. For that purpose, amphiphilic poly(N-dodecylacrylamide-co-acrylic acid) copolymers [p(DDA/AA)] with varying contents of AA were synthesized by free radical polymerization. Surface pressure (π)-area (A) isotherms of these copolymers indicated that stable polymer monolayers are formed at the air/water interface for AA mole fraction (n) ≤ 0.

Regioselective Synthesis of Eight-Armed Cyclosiloxane Amphiphile for Functional 2D and 3D Assembly Motifs.

A crystalline tetramethylcyclotetrasiloxane (TMCS)-derived amphiphile was regioselectively synthesized with eight peripheral hydrophilic amide groups and hydrophobic dodecyl chains by Pt(0)-catalyzed hydrosilylation and amidation reactions. The as-synthesized materials showed ordered lamellar structure formation in the powder form. It also exhibits superior two-dimensional (2D) monolayer formation properties at the air-water interface with unexpectedly high collapse surface pressure and elastic modulus.

Multimodal underwater adsorption of oxide nanoparticles on catechol-based polymer nanosheets.

Multimodal underwater adsorption behaviour of catechol units was demonstrated by examining the adsorption of different oxide nanoparticles on nanoscale-integrated polymer nanosheets. Catechol-based polymer nanosheets were fabricated using the Langmuir-Blodgett (LB) technique with random copolymers (p(DDA/DMA)s) of N-dodecylacrylamide (DDA) and dopamine methacrylamide (DMA). The p(DDA/DMA) nanosheets were immersed into water dispersions of SiO2, Al2O3, and WO3 nanoparticles (NPs) respectively.

High proton conductivity in the molecular interlayer of a polymer nanosheet multilayer film.

High proton conductivity was achieved in a polymer multilayer film with a well-defined two-dimensional lamella structure. The multilayer film was prepared by deposition of poly(N-dodecylacryamide-co-acrylic acid) (p(DDA/AA)) monolayers onto a solid substrate using the Langmuir-Blodgett technique. Grazing-angle incidence X-ray diffraction measurement of a 30-layer film of p(DDA/AA) showed strong diffraction peaks in the out-of-plane direction at 2θ = 2.

Superhydrophobic porous surfaces: dissolved oxygen sensing.

Porous polymer films are necessary for dissolved gas sensor applications that combine high sensitivity with selectivity. This report describes a greatly enhanced dissolved oxygen sensor system consisting of amphiphilic acrylamide-based polymers: poly(N-(1H, 1H-pentadecafluorooctyl)-methacrylamide) (pC7F15MAA) and poly(N-dodecylacrylamide-co-5- [4-(2-methacryloyloxyethoxy-carbonyl)phenyl]-10,15,20-triphenylporphinato platinum(II)) (p(DDA/PtTPP)). The nanoparticle formation capability ensures both superhydrophobicity with a water contact angle greater than 160° and gas permeability so that molecular oxygen enters the film from water.

Solvent-dependent properties of poly(vinylidene fluoride) monolayers at the air-water interface.

The present work addresses the solvent-dependent properties of Langmuir films of poly(vinylidene fluoride) (PVDF) and amphiphilic poly(N-dodecylacrylamide) (pDDA) at different mixing ratios. After introducing pDDA nanosheets, PVDF Langmuir films obtain a tremendously enhanced modulus as well as high transfer ratios using the vertical dipping method caused by the support of the pDDA two-dimensional hydrogen bonding network. Brewster angle microscopy (BAM) was used to investigate PVDF monolayers at the air-water interface in situ.

Flexible design of free-standing hybrid polymer nanosheets through bottom-up approach.

We describe the bottom-up design of highly ordered free-standing nanofilms consisting of polymer Langmuir-Blodgett films (polymer nanosheets). Polymer nanosheets enable the incorporation of a wide variety of functional groups such as reactive components and chromophores, which serve as building blocks of free-standing nanofilms. We demonstrated a free-standing fluorescent hybrid nanofilm in which the separation between gold nanoparticles and fluorophores was tuned at the nanometer scale.

A trilayer film approach to multicolor electrochromism.

Development of multicolored electrochromic materials is important to realize their applications in electronic devices such as full color electronic paper. One method to increase the number of colors in an electrochromic device is by color mixing. A simple method for color mixing involves two electrochromes deposited at different working electrodes.

Enhancement of proton transport in an oriented polypeptide thin film.

Proton transport properties of a partially protonated poly(aspartic acid)/sodium polyaspartate (P-Asp) were investigated. A remarkable enhancement of proton conductivity has been achieved in the thin film. Proton conductivity of 60-nm-thick thin film prepared on MgO(100) substrate was 3.

Helicity-selective photoreaction of single-walled carbon nanotubes with organosulfur compounds in the presence of oxygen.

This report describes a helicity-selective photoreaction of single-walled carbon nanotubes (SWNTs) with disulfide in the presence of oxygen. The SWNTs were characterized using absorption, photoluminescence (PL), Raman, and X-ray photoelectron spectroscopy, scanning electron microscopy, and current-voltage (I-V) measurements. Results showed remarkable helicity-selective (metallic SWNTs/semiconducting SWNTs and diameter) functionalization of SWNTs.

Synthesis and monolayer behavior of organogermanium clusters.

Several organogermanium clusters (Or-GeCs) with different organic capping reagents have been synthesized, and their monolayer behaviors on a water surface studied. GeCl(4) and organic bromides were reacted in a one-pot process using magnesium to synthesize the corresponding Or-GeCs. The structures of the Or-GeCs were characterized by UV-vis, NMR, and FT-IR spectroscopy.

Direct deposition of two nanomaterials with the same surface charge using a liquid-liquid interface.

Two negatively charged nanoparticles (SDS-coated SWCNT and polydiacetylene nanocrystals) were sequentially adsorbed onto the same water-hexane interface. The absorbed film can be transferred onto a solid substrate. Repeating the adsorption and transfer process enables assembly of the two nanoparticles in a layer-by-layer growth fashion up to three bi-layers.

Spontaneous emission control of CdSe/ZnS nanoparticle monolayer in polymer nanosheet waveguide assembled on a one-dimensional silver grating surface.

We present spontaneous emission control of a core-shell CdSe/ZnS nanoparticle array assembled with polymer ultrathin films consisting of polymer nanosheets on a silver grating substrate, which served as a unique and simple photonic cavity. The grating-coupled waveguide modes enabled 10(3) order luminescence enhancement and one-fourth spectral narrowing. The light emission from a CdSe/ZnS nanoparticle array can be controlled by tuning the film thickness of hybrid polymer nanoassemblies, which provides multiple emission performance with good tuning ability from red to green at low-power continuous wave laser excitation (∼μW).

Effects of hydrogen bonding on the monolayer properties of amphiphilic double-decker-shaped polyhedral silsesquioxanes.

"Core-corona" type amphiphiles, which comprise double-decker-shaped POSSs (DDSQs) as the core and two or four di(ethylene glycol) (DEG) units as the coronae, have recently been reported to form a stable monolayer at the air-water interface. In this paper, another core-corona amphiphile, 2DEGNH-DDSQ, which has a urethane group at the end of the coronae, was synthesized to elucidate the effects of hydrogen bonding on monolayer properties. The surface pressure-area isotherm and Brewster angle microscopy revealed that 2DEGNH-DDSQ initially formed rodlike assemblies.