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PS-b-PAA/copper composite two-dimensional nanoflowers with highly heterogeneous catalytic activity and good stability was fabricated at the liquid/liquid interface. To design and prepare heterogeneous catalysts with both high catalytic activity and good stability is still a challenge. Herein, we fabricated a composite Cu/PS-b-PAA film consisting of unique nanoflowers for the heterogeneous catalytic reactions such as hydrogenation of nitroarenes in aqueous solutions at the planar liquid/liquid interface through the interfacial adsorption and self-assembly process. The nanoflowers are comprised of nanoplates with a thickness of about 10 nm. The nanoplates have layered structure composed of an inner layer of hydrophobic PS and two surface layers of hydrophilic PAA where the copper species are dispersed. The composite film exhibited high catalytic activity for the reduction of p -nitroaniline (p -NA) in aqueous solutions and the rate constant reached to 396.45 s−1 g−1. Inaddition, the composite film also showed good stability and high recyclability without any changes in the rate constant and conversion efficiency in 15 successive cycles. These should be attributed to the special structure of the composite nanoflowers. We developed an excellent heterogeneous catalyst system possessed of both high activity and good stability through delicate design and fabrication. [ABSTRACT FROM AUTHOR]

Hypothesis Our previous studies have shown that the metal nanoparticle/polymer composite structures fabricated at the liquid/liquid interface have good reusability but lower catalytic activity for heterogeneous reactions in aqueous solutions. This should be attributed to the poor water wettability and more compact structure of the polymer matrices. Therefore, it should be possible to improve the catalytic activity through designing and fabricating a porous composite structure with good water wettability. Experiments A modified liquid/liquid interface adsorption and fabrication method was used. An aqueous solution of copper acetate and a chloroform/DMF mixed solution of PS- b -PAA acted as the two phases. Through spontaneous emulsification, self-assembly of the polymer molecules with Cu 2+ ions in the droplets, and adsorption of the formed spherical micelles and nanofibers to the planar liquid/liquid interface, a porous composite microstructure was formed. Findings This structure consisted of nanofiber-connected nanospheres which have a PS core and a PAA corona. Tiny and well-dispersed Cu nanoparticles were embedded in the hydrophilic corona and were adsorbed on the nanofibers surface as well. After physical cross-linking with 1,6-diaminohexane, the composite material exhibited high catalytic activity and good reusability for the reactions in aqueous solutions. For example, the rate constant for the reduction of p -nitroaniline reached 1965 s −1  g −1 . [ABSTRACT FROM AUTHOR]

An emulsion-directed assembly and adsorption approach has been used to fabricate composite films of polystyrene-b-poly(acryl acid)-b-polystyrene (PS-b-PAA-b-PS) and Eu 3+ and La 3+ ions at the planar liquid/liquid interface of the polymer DMF/chloroform (1:1, v/v) mixed solution (lower phase) and aqueous solutions of the corresponding salts (upper phase). The lower phase gradually transformed to a water-in-oil (W/O) emulsion via spontaneous emulsification due to the “ouzo effect”. Polymer molecules and the metal ions assembled around emulsion droplets that adsorbed at the planar liquid/liquid interface at last, resulting in formation of composite films. The film morphologies and structures depend on Ln 3+ ions: polymer/Eu 3+ composite films were foam films composed of microcapsules ranging in size from several hundreds of nanometers to micrometers, while polymer/La 3+ composite films were composed of hollow spheres several tens of nanometers in size. Fourier transform infrared (FTIR) spectra revealed that the coordination modes of carboxyl groups to Eu 3+ and La 3+ were bridging bidentate and ionic, respectively, in the two types of composites. These results indicate that stable microcapsules can be fabricated around droplets for polymer/Eu 3+ systems, while microcapsules of polymer/La 3+ are unstable. This leads to different film morphologies and structures. Compositions of these films were characterized using energy-dispersive spectroscopy (EDS) and X-ray photoelectron spectroscopy (XPS). In addition, foam films of polymer/Eu 3+ /2,2′-bipyridine (bpy) were fabricated using this approach, and their photoluminescence properties were investigated. [ABSTRACT FROM AUTHOR]

Abstract: Gold nanoparticle-doped poly(2-vinylpyridine)-block-polystyrene-block-poly(2-vinylpyridine) (P2VP-b-PS-b-P2VP) thin films were prepared at the planar liquid/liquid interface between the chloroform solution of the polymer and aqueous solution of HAuCl4. Transmission electron microscopic (TEM) investigations revealed that foam films composed of microcapsules as well as one-dimensional belts were formed, and numerous Au nanoparticles were incorporated in the walls of the microcapsules and the nanobelts. The walls and the belts have layered structure. The formation mechanism of the foams and the belts was attributed to adsorption of the polymer molecules, combination of the polymer molecules with AuCl4 − ions, microphase separation and self-assembly of the composite molecules at the interface. This microstructure is different apparently from those formed in solutions, in casting or spin-coating thin films and at the air/water interface of this triblock copolymer, reflecting unique self-assembly behavior at the liquid/liquid interface. This microstructure is also different from those formed by homo-P2VP and P4VP-b-PS-b-P4VP at the liquid/liquid interface, indicating the effects of molecular structures on the self-assembly behaviors of the polymers. After further treatment by UV-light irradiation and KBH4 aqueous solution, the gold species were reduced completely, as indicated by UV–vis spectra and X-ray photoelectron spectra (XPS). Thermogravimetric analysis indicated that the composite films have high thermal stability, and the content of gold was estimated to be about 9.1%. These composite films exhibited high catalytic activity for the reduction of 4-nitrophenol by KBH4 in aqueous solutions. [Copyright &y& Elsevier]

Thefoam films of polystyrene-b-poly(acrylic acid)-b-polystyrene (PS-b-PAA-b-PS) doped with Cd(II) or Pb(II) species were fabricated at the planarliquid/liquid interfaces between a DMF/chloroform (v/v: 1/1) solutionof the polymer and aqueous solutions containing cadmium acetate orlead acetate at ambient temperature. Optical microscopic observationshows the thin film is uniform on a larger length scale. Transmissionelectron microscopic (TEM) investigations reveal that the foam filmsare made up of microcapsules with the size of several hundreds ofnanometers to micrometers. The walls of the microcapsules have a layeredstructure decorating with nanofibers and hollow nanospheres, wherenumerous inorganic fine nanoparticles are dispersed homogeneously.The film formation is a result of emulsion droplet-templated assemblyand adsorption of the formed microcapsules at the planar liquid/liquidinterface. Because of the miscibility of DMF with chloroform and water,DMF migrates to the aqueous phase while water migrates to the organicphase across the interface, resulting in the formation of a W/O emulsion,as revealed by optical microscopic observation, freeze fracture transmissionelectron microscopic (FF-TEM) observation, and dynamic laser scattering(DLS) investigation. The triblock copolymer molecules and the inorganicspecies adsorb and self-assemble around the emulsion drops, leadingto the formation of the composite microcapsules. X-ray photoelectronspectroscopic (XPS) and FTIR spectroscopic results indicate that twokinds of Cd(II) or Pb(II) species, metal oxide or hydroxide, resultingfrom the hydrolysis of the metal ions and the coordinated metal ionsto the carboxyl groups coexist in the formed thin films, which transformto metal sulfide completely after treating with hydrogen sulfide toget metal sulfide nanoparticle-doped polymer thin films. [ABSTRACT FROM AUTHOR]

Abstract: Composite thin films of poly(t-butyl methacrylate)-block-poly(2-vinyl pyridine) (PtBMA-b-P2VP) doped with silver or gold nanoclusters or nanoparticles were fabricated at the liquid/liquid interface between the polymer chloroform solution and AgNO3 or HAuCl4 aqueous solution. The formation of the thin films results from the adsorption of the polymer molecules at the interface, combination with the inorganic species in the water phases, and self-assembly of the composite molecules. Different from homo-P2VP and polystyrene-block-poly(2-vinyl pyridine) (PS-b-P2VP) that self-assemble into foam film and honeycomb structure, respectively, two kinds of morphologies (foam and honeycomb structures) are formed simultaneously for PtBMA-b-P2VP, reflecting different assembling behaviors of these polymers at the interface. Silver or gold nanoclusters or nanoparticles were generated in the polymer films during the assembly process and further reduction of the combined precursors, which show high catalytic activity and durability for the reduction of 4-nitrophenol and other nitro-compounds. [Copyright &y& Elsevier]

Highlights: [•] Composite films with different structures were formed at the liquid/liquid interface. [•] These films are composed of diblock or triblock copolymers and inorganic species. [•] PS-b-P4VP/Au and PS-b-P4VP/Ag have honeycomb and foam structure, respectively. [•] P4VP-b-PS-b-P4VP/Au forms a free-standing film with a nanosphere array structure. [•] Co-adsorption and self-assembly of polymer and the ions lead to the film formation. [ABSTRACT FROM AUTHOR]

Highlights: [•] Composite network and microporous P2VP/Cu(II) structures were fabricated. [•] Composite nano-shuttle and microbelt of P2VP/Cu(OH)2 were obtained. [•] These nanostructures were fabricated at the liquid/liquid interface. [•] Adsorption, hydrolysis and self-assembly processes were involved in the fabrication. [•] The two kinds of nanostructures exhibited different catalytic properties. [Copyright &y& Elsevier]

Highlights: [•] Composite films with honeycomb structure were formed at the liquid/liquid interface. [•] These films are composed of block copolymer PS-b-P2VP and Ag+ or ions. [•] Co-adsorption and self-assembly of polymer and the ions lead to the film formation. [•] Transformed metal nanoparticles exhibit high and durable catalytic activity. [ABSTRACT FROM AUTHOR]

Abstract: Free-standing films of poly(2-vinylpyridine) doped with Ag+ ions were fabricated at the planar liquid/liquid interface of an aqueous solution of AgNO3 and a chloroform solution of the polymer through adsorption of the polymer molecules, combination with Ag+ ions, and self-assembly of the composite species. Transmission electron microscopic (TEM) investigations indicated that the films were composed of planar thin layers decorated with separated microcapsules and foam structures of conglutinated microcapsules, and no Ag nanoparticles formed in the pristine films. After UV-light irradiation and KBH4 aqueous solution treatment, Ag nanoparticles with the average size of 3.2nm appeared and incorporated in the polymer matrices. X-ray photoelectron spectra (XPS) and UV–vis spectra are consistent with the TEM observations. Thermogravimetric analysis (TGA) showed good thermal stability of the composite films. The silver content was estimated to be 24.0% from the TG curve, closing to the calculated value. The catalytic performance of the composite films was evaluated by using the reduction of nitro-compounds, including nitrobenzene, 4-nitrophenol, and 4-nitrobenzoic acid by KBH4 in aqueous solutions. The results indicated that the composite films have high and durable catalytic activity. The apparent reaction constants are related to the size of the nitro-compounds, suggesting that the Ag nanoparticles were incorporated in the matrices, and the diffusion of the reactant molecules has a great influence on the catalytic reaction. [Copyright &y& Elsevier]

Abstract: Gold nanoparticle-doped microcapsules and foamlike films of poly(N-vinylcarbazole) (PVK) were prepared through a self-assembly process at a liquid/liquid interface. The liquid/liquid interface was formed by an aqueous solution of HAuCl4 and a chloroform solution of PVK. The composite structures were characterized using transmission electron microscopy (TEM), high-resolution TEM (HRTEM), and UV-vis spectroscopy. The results revealed that microcapsules with the size of several hundreds of nanometers and foamlike thin films were formed, and small gold nanoclusters and nanoparticles embedded in the walls. The formation of these composite nanostructures was the result of the adsorption and combination of PVK molecules with AuCl4 − ions, self-assembly of the composite molecules, and reduction of the complex ions at the liquid/liquid interface. The composite structures exhibited effective catalytic activity for the reduction of 4-nitrophenol (4-NP) by KBH4 in aqueous solutions. [Copyright &y& Elsevier]

Abstract: Gold nanoparticle-doped poly(2-vinylpyridine) (P2VP) microcapsules and foam films were synthesized and assembled at the P2VP chloroform solution/HAuCl4 aqueous solution interface at 25°C. It was found that Au nanoparticles with the average diameter of 2.1nm were homogeneously embedded in and adsorbed on the walls of the capsules and foams, the nanoparticles were composed of Au(0) and Au(III) with the molar ratio of about 75/25, and the mass percent of Au elements was measured to be 19.65%. The formation of the nanostructures was attributed to the self-assembly of P2VP at the liquid/liquid interface, the simultaneous reduction of ions by a small amount of ethanol in the chloroform and adsorption of ions. After irradiated by UV-light for 1h, the average diameter of the nanoparticles was found to be 2.2nm, and the ions were transformed to Au(0) completely. The catalytic performance of these composite nanostructures were evaluated by using the reduction of 4-nitrophenol (4-NP) by potassium borohydride in aqueous solutions. The catalytic activity was very high in the first cycle, decreased rapidly and slightly in the second and third cycles, respectively, due to the aggregation of some nanoparticles, and stabilized after the third cycle. [Copyright &y& Elsevier]

The composite poly(2-vinylpyridine) (P2VP)-Ag纆like thin films were prepared at the interface between AgNO3aqueous solution and polymer chloroform solution at 25 °C. An X-ray photoelectron spectroscopy (XPS) investigation indicated that Ag誉 in the composite films were partially transformed to Ag atoms after irradiated by UV-light and completely transformed to Ag atoms after being treated with KBH4aqueous solution. Ag nanoparticles with the average sizes of 2.71 ± 0.82 and 3.28 ± 1.20 nm were generated in these two transferred films with different treatments, respectively. Transmission electron microscopy (TEM) and high-resolution TEM (HRTEM) images showed clearly that the composite films were composed of microcapsules whose walls had multilayer structures, and the nanoparticles were incorporated in the walls. The formation of the composite films at the liquid–liquid interface was attributed to the adsorption of the polymer molecules at the interface, coordination between the pyridine groups and Ag誉, and self-assembly of the composite molecules. Furthermore, the catalytic activity of the composite films was evaluated using the reduction of 4-nitrophenol (4-NP) by KBH4. The results demonstrated that the composite thin films have high and durable catalytic activity. [ABSTRACT FROM AUTHOR]

Abstract: Platinum nanoparticle-doped polymer foam-like thin films were prepared via a synthesis and assembly process at the liquid/liquid interface of a chloroform solution of poly(2-vinylpyridine) and an aqueous solution of chloroplatinic acid hydrate and a subsequent UV-light irradiation process. Transmission electron microscopy, high-resolution transmission electron microscopy and X-ray photoelectron spectroscopy investigations indicated that the foam-like thin films formed at the interface were composed of polymer molecules, and Pt(II) and Pt(IV) ions. Platinum nanoparticles with average diameter of 2.70±0.35nm appeared after UV-light irradiation, which were embedded in and adsorbed on the walls of the foams. The formation of the composite nanostructures at the interface was attributed to self-assembly of the polymer molecules at the liquid/liquid interface, reduction of PtCl6 2−, and interaction between PtCl6 2−/intermediate PtCl4 2− ions and the protonated pyridine groups. The catalytic activity of the composite film for the reduction of methylene blue by potassium borohydride in aqueous solutions was evaluated. The apparent rate constant decreased gradually with increasing the number of runs due to the partially leaching of Pt nanoparticles and became stable after the fifth cycle, indicating that the composite film can be used as an effective, stable and reusable catalyst. [Copyright &y& Elsevier]