Facile fabrication of conducting polymer hydrogels via supramolecular self-assembly

We describe a simple and versatile method to fabricate conducting polymer hydrogels via supramolecular self-assembly between polymers and multivalent cations; the as-prepared hydrogels are potentially applicable in the fields of electrosensors, chemical release and artificial muscles.     

Facile fabrication of mechanochromic-responsive colloidal crystal films

This paper presents a simple approach to fabricate a reversible mechanochromic-responsive crystal film based on the room-temperature film-formation of monodisperse polymer latex by the aid of nanosilica particles. In this approach, when the "soft" colloidal polymer spheres were blended with colloidal silica particles and then cast on a substrate, followed by drying at room temperature for self-assembly, an elastic crystal film was directly obtained. This crystal film has not only reversible and repeatable mechanochromic-responsive property, but also tunable color and peak position covering almost entire visible spectral region, depending upon the sizes of polymer spheres and strains. This optical response is attributed to the variation of lattice spacing during deformation.     

Macroscopic, free-standing ag-reduced, graphene oxide janus films prepared by evaporation-induced self-assembly

A facile, efficient, and unique self-assembly process for the preparation of the macroscopic, free-standing, Ag-reduced, graphene oxide (Ag-RGO) Janus films, which exhibit a unique asymmetry of their two surfaces with macroscopic dimensions, is presented. A novel strategy using an evaporation-induced, self-assembly (EISA) process is shown to be a powerful and flexible method for synthesizing well-defined Janus thin films.     

Interface-directed self-assembly of gold nanoparticles and fabrication of hybrid hollow capsules by interfacial cross-linking polymerization

Amphiphilic gold nanoparticles (AuNPs) were produced at liquid-liquid interface via ligand exchange between hydrophilic AuNPs and disulfide-containing polymer chains. By using oil droplets as templates, hybrid hollow capsules with AuNPs on the surfaces were obtained after interfacial cross-linking polymerization. The volume ratio of toluene to water exerts an important effect on the size of capsules. The average size of the capsules increases with the volume ratio. Transmission electron microscopy (TEM), scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used to characterize the hollow structures. In this research, not only one-component but also multicomponent hollow capsules were prepared by copolymerization of acrylamide and hybrid AuNPs at liquid-liquid interface. Because of the improvement in hydrophilicity of the hollow capsules, the average size of multicomponent capsules is bigger than one-component ones in aqueous solution.     

Controllable fabrication of porous free-standing polypyrrole films via a gas phase polymerization

A facile gas phase polymerization method has been proposed in this work to fabricate porous free-standing polypyrrole (PPy) films. In the presence of pyrrole vapor, the films are obtained in the gas/water interface spontaneously through the interface polymerization with the oxidant of FeCl(3) in the water. Both the thickness of the film and the size of the pores could be controlled by adjusting the concentrations of the oxidant and the reaction time. The as-prepared PPy films exhibited a superhydrophilic behavior due to its composition and porous structures. We have demonstrated a possible formation mechanism for the porous free-standing PPy films. This gas phase polymerization is shown to be readily scalable to prepare large area of PPy films.     

Mechanical properties of interfacial films formed by lysozyme self-assembly at the air-water interface

We present the first characterization of the mechanical properties of lysozyme films formed by self-assembly at the air-water interface using the Cambridge interfacial tensiometer (CIT), an apparatus capable of subjecting protein films to a much higher level of extensional strain than traditional dilatational techniques. CIT analysis, which is insensitive to surface pressure, provides a direct measure of the extensional stress-strain behavior of an interfacial film without the need to assume a mechanical model (e.g., viscoelastic), and without requiring difficult-to-test assumptions regarding low-strain material linearity. This testing method has revealed that the bulk solution pH from which assembly of an interfacial lysozyme film occurs influences the mechanical properties of the film more significantly than is suggested by the observed differences in elastic moduli or surface pressure. We have also identified a previously undescribed pH dependency in the effect of solution ionic strength on the mechanical strength of the lysozyme films formed at the air-water interface. Increasing solution ionic strength was found to increase lysozyme film strength when assembly occurred at pH 7, but it caused a decrease in film strength at pH 11, close to the pI of lysozyme. This result is discussed in terms of the significant contribution made to protein film strength by both electrostatic interactions and the hydrophobic effect. Washout experiments to remove protein from the bulk phase have shown that a small percentage of the interfacially adsorbed lysozyme molecules are reversibly adsorbed. Finally, the washout tests have probed the role played by additional adsorption to the fresh interface formed by the application of a large strain to the lysozyme film and have suggested the movement of reversibly bound lysozyme molecules from a subinterfacial layer to the interface.     

Oil-water interfacial self-assembly: a novel strategy for nanofilm and nanodevice fabrication

How to integrate individual nanostructures into macroscopic thin films has become one of the most intriguing fields in nanoscience and nanotechnology due to the unique properties and important applications of these functional films. Since being discovered in 2004, oil-water interfacial self-assembly of nanostructures has become a novel strategy for fabrication of nanofilms. It is a powerful bottom-up approach for film fabrication due to the low cost and high efficiency, and is simple and universal for almost all low-dimensional nanostructures. In this article, we provide a critical review of the state-of-the-art research activities in this burgeoning self-assembly strategy. We first discuss the thermodynamic mechanism of the oil-water interfacial self-assembly, then the self-assembly of various low-dimensional nanostructures including nanoparticles, one-dimensional (1D) nanostructures, two-dimensional (2D) nanostructures at an oil-water interface developed so far to fabricate high-quality nanofilms. Finally, we present some progress on the construction of functional nanofilm-based nanodevices from this novel strategy based on our research. We conclude this review with critical comments on advantages and the experimental challenges, and further propose the future research and development of this self-assembly strategy for nanodevice construction (105 references).     

Facile regulation of glutaraldehyde-modified graphene oxide for preparing free-standing papers and nanocomposite films

Colloidal suspensions of glutaraldehyde (GA) crosslinked or grafted graphene oxide (GO) sheets were fabricated by simply tailoring the feed sequence. The different structures were confirmed by Fourier transform infrared spectra and X-ray diffraction. As demonstration of the utilities, the different colloidal suspensions were used to prepare free-standing papers by flow-directed filtration and poly(vinyl alcohol) (PVA)-based nanocomposite films by casting. Free-standing papers from GA crosslinked GO sheets exhibited better mechanical properties than unmodified GO paper, while nanocomposite films from GA grafted GO exhibit higher tensile strength and Young’s modulus.     

Facile electrosynthesis and thermoelectric performance of electroactive free-standing polythieno[3,2-b]thiophene films

Polythieno[3,2-b]thiophene (PTT) was electrosynthesized by facile anodic oxidation of thieno[3,2-b]thiophene (TT) in three systems: boron trifluoride diethyl etherate (BFEE), acetonitrile (ACN), and dichloromethane solutions. The onset oxidation potential of TT in BFEE was determined to be 0.62?V vs. Ag/AgCl, which was much lower than those in ACN and dichloromethane solutions. PTT films exhibited excellent electrochemical property, high thermal stability, good redox activity, and stability. Free-standing PTT films with good mechanical property can be obtained from BFEE solution, whose structure and morphology were characterized by FT-IR, UV?Cvisible spectra, and scanning electron microscopy. With an electrical conductivity of 1.5?S?cm^?1 and a Seebeck coefficient of 85???V?K^?1 at 306?K, the as-prepared free-standing PTT films showed a certain thermoelectric property. The dimensionless figure-of-merit of PTT films was estimated to be 2.3?×?10^?3 at 306?K, which was much higher than those of some organic thermoelectric materials reported previously. All these results indicated that PTT films may have potential applications in the thermoelectric field.     

Coordination-polymer films by reactive self-assembly

A novel self-assembly technique for the growth of insoluble and intractable thin organic films is presently reported. Bifunctional 8,8′-dihydroxy-5,5′-biquinoline (bisquinoline) is reactively self-assembled with diethyl zinc to form a linear coordination polymer. FTIR, UV/VIS spectroscopy, profilometry, and photoluminescence measurements were used to characterize these new multilayer films. The growth of these films on glass substrates was monitored by increasing absorbance at 396.6 nm using UV/VIS spectroscopy and by profilometry. FTIR spectroscopy indicated that the self-assembled films are polymeric in nature. The reduction of end-group hydroxyls and a significant red-shift of the photoluminescence emission spectrum with respect to zinc bisquinoline powder was attributed to an increase in conjugation length.     

Facile fabrication of polymer-dispersed liquid crystal films via nucleophile-initiated thiol-ene click reaction

Nucleophile-initiated thiol-ene click reaction was employed to prepare polymer-dispersed liquid crystal (PDLC) films initiated by 4-dimethylaminopyridine (DMAP). The PDLC films were prepared in different temperature. It is found that the reaction temperature has a big influence on the electro-optical properties of PDLC films and 60°C is the optimal temperature to fabricate PDLC film which has high ON state transmittance (T_on) and low OFF state transmittance (T_off). UV-Visible spectrophotometer, scanning electron microscopy and polarised optical microscope were employed to explore the obtained PDLC films. Nucleophile-initiated thiol-ene click reaction, without UV-light, probably provides a new pathway to prepare PDLC films.     

Facile method for fabrication of nanocomposite films with an ordered porous surface

This paper presents a novel and facile method for the fabrication of nanocomposite films with ordered porous surface structures. In this approach, a water-borne poly(styrene-co-butyl acrylate-co-acrylic acid)/silica nanocomposite dispersion was synthesized in situ by surfactant-free emulsion polymerization by using 3-allyloxy-2-hydroxy-1-propanesulfonate as a polymerizable surfactant. When this dispersion was dried to form a film at a certain temperature, an ordered porous structure could be directly obtained on the surface of the nanocomposite film. SEM, TEM, and AFM were employed to observe the morphology, and XPS and particle analyzer were used to analyze the surface composition of the ordered porous nanocomposite film and the particle size, respectively.     

Facile and controllable one-step fabrication of molecularly imprinted polymer membrane by magnetic field directed self-assembly for electrochemical sensing of glutathione

Based on magnetic field directed self-assembly (MDSA) of the ternary Fe₃O₄@PANI/rGO nanocomposites, a facile and controllable molecularly imprinted electrochemical sensor (MIES) was fabricated through a one-step approach for detection of glutathione (GSH). The ternary Fe₃O₄@PANI/rGO nanocomposites were obtained by chemical oxidative polymerization and intercalation of Fe₃O₄@PANI into the graphene oxide layers via π–π stacking interaction, followed by reduction of graphene oxide in the presence of hydrazine hydrate. In molecular imprinting process, the pre-polymers, including GSH as template molecule, Fe₃O₄@PANI/rGO nanocomposites as functional monomers and pyrrole as both cross-linker and co-monomer, was assembled through N–H hydrogen bonds and the electrostatic interaction, and then was rapidly oriented onto the surface of MGCE under the magnetic field induction. Subsequently, the electrochemical GSH sensor was formed by electropolymerization. In this work, the ternary Fe₃O₄@PANI/rGO nanocomposites could not only provide available functionalized sites in the matrix to form hydrogen bond and electrostatic interaction with GSH, but also afford a promoting network for electron transfer. Moreover, the biomimetic sensing membrane could be controlled more conveniently and effectively by adjusting the magnetic field strength. The as-prepared controllable sensor showed good stability and reproducibility for the determination of GSH with the detection limit reaching 3 nmol L⁻¹ (S/N = 3). In addition, the highly sensitive and selective biomimetic sensor has been successfully used for the clinical determination of GSH in biological samples.     

Facile fabrication of superhydrophobic surface from micro/nanostructure metal alkanethiolate based films

A series of superhydrophobic surfaces with micro/nanostructure have been successfully achieved by a simple process via the reaction between metal (such as Cd and Zn) salts and alkanethiolates.     

Facile fabrication of composites of platinum nanoparticles and amorphous carbon films by catalyzed carbonization of cellulose fibers

Composites of platinum nanoparticles and amorphous carbon films have been facilely fabricated by catalyzed carbonization of cellulose fibers.     

Facile fabrication of rutile monolayer films consisting of well crystalline nanorods by following an IL-assisted hydrothermal route

In this study, rutile films consisting of rectangular nanorods were facilely deposited on glass substrates from strongly acid solution of TiCl₄. The highly ordered array of nanorods was realized in presence of ionic liquid (IL) of [Bmim]Br by following a hydrothermal process. In this process, Degussa P25 nanoparticles served as seeds that were pre-deposited on the substrates to facilitate the array of rutile nanorods. X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Raman spectrum were used to characterize the obtained nanorod films. The measurements showed that the nanorods were rectangular with width of 100-200 nm and length of more than 1 μm, and grew up typically along c-axis to form the arrays against the substrate. The presence of IL was found vital for the formation of rutile nanorods, and the suitable molar ratio of [Bmim]Br to TiCl₄ ranged from 500:1 to 1500:1. The excessive [Bmim]Br may hinder the precipitation of rutile particles.     

Facile self-assembly of the first diphosphametacyclophane

The reaction of isophthaloyl chloride and methyl-bis(trimethylsilyl)phosphane under mild conditions affords high yields of m-{-C(O)-C(6)H(4)(C(O)PMe)}(2) (1,10-dimethyl-1,10-diphospha-[3.3]-metacyclophane-2,9,11,18-tetraone): the first example of a diphosphametacyclophane.     

Facile fabrication of hollow polystyrene nanocapsules by microemulsion polymerization

The fabrication of polymer nanocapsules with tailored dimensions has been accomplished by microemulsion polymerization using different surfactants.     

Facile fabrication of photonic MOF films through stepwise deposition on a colloid crystal substrate

Based on stepwise deposition of MOF films on a colloid crystal substrate, a strategy for fabricating photonic MOF films was developed. We found that the integration of a photonic structure endows MOF materials with unique optical properties, which can be used as a general and effective transduction scheme for a convenient study of the host-guest chemistry of MOFs.     

Postsynthesis stabilization of free-standing mesoporous silica films

Mixed ammonia-water vapor postsynthesis treatment provides a simple and convenient method for stabilizing mesostructured silica films. X-ray diffraction, transmission electron microscopy, nitrogen adsorption/desorption, and solid-state NMR (13C, 29Si) were applied to study the effects of mixed ammonia-water vapor at 90 degrees C on the mesostructure of the films. An increased cross-linking of the silica network was observed. Subsequent calcination of the silica films was seen to cause a bimodal pore-size distribution, with an accompanying increase in the volume and surface area ratios of the primary (d = 3 nm) to secondary (d = 5-30 nm) pores. Additionally, mixed ammonia-water treatment was observed to cause a narrowing of the primary pore-size distribution. These findings have implications for thin film based applications and devices, such as sensors, membranes, or surfaces for heterogeneous catalysis.