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Two-dimensional helical nanowire and nanosphere superstructures of PS- b -P2VP/S-mandelic acid with homochirality have been fabricated at the liquid/liquid and air/liquid interfaces via two kinds of approaches, respectively. [Display omitted] • PS-b-P2VP co-assembled with S-mandelic acid in the liquid/liquid interfacial phase. • Helical nanowires and nanospheres with homochirality formed. • These nanowires and nanospheres further assembled into 2D superstructures. • This is a one-step method to fabricate 2D superstructures of helical nanostructures. Chiral supramolecules have attracted great research interest due to their unique properties and functions. How to assemble them into the ordered superstructures, however, remains a challenge. In this paper, two methods have been developed to fabricate such superstructures. In method I, polystyrene- b -poly (2-vinylpyridine) (PS- b -P2VP) and S-mandelic acid (S-MA) diffused from the oil and aqueous phases respectively to the oil/water interface, combined and self-assembled into helical nanowires and nanospheres with monochirality, and formed parallel-aligned nanowire arrays and close-packed arrays at the liquid/liquid interface. In method II, PS- b -P2VP in DMF droplets was introduced into the aqueous solution of S-MA through a liquid/liquid interfacial phase transfer process. Then the polymer molecules self-assembled into helical nanowires and nanospheres with monochirality in the aqueous phase, which adsorbed at the air/liquid interface and organized into superstructures. The formation of chiral aggregates should be attributed to the induction of S-MA, while the superstructures at the interfaces were considered to result from the modulation by the interfacial pressures. This study has developed one-step techniques to assemble the chiral aggregates and superstructures, which is expected to become universal for fabrication of functional superstructures. [ABSTRACT FROM AUTHOR]

Large area layered ultrathin films have attracted much attention in recent years, as they have ordered structure, unique properties and potential applications in various areas, such as transportation, separation and catalysis. Herein, we reported the successful preparation of large area layered ultrathin films of a bola-type amphiphilic molecule, perfluorodecanedioic acid (PFDDA) at the liquid/liquid interface in the absence or presence of metal ions. It was found that the ultrathin thin film of PFDDA/Zn(II) has a hexagonal closed packed crystal structure with the crystal parameters of a = 0.302 and c = 1.9 nm. The formation of the film was attributed to the weaker intermolecular interactions, the restriction of the interfacial phase, and the epitaxial growth. However, dodecanedioic acid (DDDA) and docosanedioic acid (DCDA) formed ultrathin nanosheets instead of large area films through this approach, reflecting different self-assembly behavior of the perfluorocarbon chains and the hydrocarbon chains. Large area layered ultrathin films of a bola-amphiphilic perfluorodecanedioic acid were fabricated at the liquid/liquid interface. [Display omitted] • Large area layered ultrathin films of bola-amphiphilic molecules were fabricated. • The amphiphilic molecule is perfluorodecanedioic acid. • The films were fabricated at the planar liquid/liquid interface. • The fabrication process includes nucleation and 2D epitaxial growth. • Amphiphobic effects, coordination or H-bonds are responsible for the film formation. [ABSTRACT FROM AUTHOR]

The nanostructures based on polymers have attracted much research interest because of their rich morphologies, unique properties and potential applications in various fields. In particular, helical nanostructures have been research hotspots in recent years. In this work, composite non-helical and helical nanowire arrays of atactic poly(2-vinylpyridine) (P2VP), and block copolymers polystyrene- block -poly(2-vinylpyridine) (PS- b -P2VP) were fabricated successfully with inorganic species such as HAuCl 4 through a liquid/liquid interfacial adsorption and self-assembly approach without addition of any chiral inducers. The formation process of the helical nanowires of P2VP includes the following steps, i.e. adsorption of the polymer molecules and HAuCl 4 at the interface, the following protonation of pyridine groups, straightening of the P2VP chains by mutual repulsion between the protonated pyridine groups, aggregation of the P2VP chains due to the hydrophobic interactions between the backbones, and ordered organization of the pyridine groups through π-π interactions. The helical nanowires of PS- b -P2VP are worm-like micelles with a PS core and a P2VP shell, which are formed through the self-assembly of the block copolymer molecules with HAuCl 4 within the interfacial phase with the help of hydrophobic interaction between the PS blocks and orderly stacking of the P2VP blocks. The different formation mechanisms reflected the effects of molecular structure on the self-assembly of polymers. In addition, the formed nanowires further self-organize into ordered arrays due to the increasing interfacial pressure during the generation of the nanowires. The results of this study expand the scope of research on polymer self-assembly and the application of liquid/liquid interfacial self-assembly techniques to acquire highly ordered supramolecular nanostructures. [Display omitted] • PS and PS-b-P2VP self-assembled into helical nanowires with chloroauric acid. • The nanowires formed in the liquid/liquid interfacial phase. • These nanowires further organized into parallel arrays. • The PS nanowires result from chain straightening, aggregation and ordered packing. • The PS-b-P2VP nanowires are actually worm-like micelles. [ABSTRACT FROM AUTHOR]

Amphiphilic block copolymers can self-assemble into various aggregates in which functional inorganic nanoparticles and organic chromophores can be incorporated. A variety of fabrication methods have been developed. In this work, the liquid/liquid interface mass transfer-assisted self-assembly method was extended to fabricate composite organized structure of polystyrene-b-polyacrylic acid (PS-b-PAA) with small organic molecules, such as diamines, dopamine and dyes. It was found that long uniform nanowires, hollow spheres and foams were generated when using these organic molecules under different conditions, which correspond to worm-like micelles, vesicles and aggregates of microcapsules, respectively. The length of the nanowires reaches to several tens of micrometers. The influence of the molecular structure of the organic molecules, especially the diamines was investigated and discussed, and the formation mechanism of these aggregates was analyzed. This method may be developed to a facile and useful approach to fabricate functional composite structure of block copolymers and small molecules. [ABSTRACT FROM AUTHOR]

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]

It is of great importance to explore the self-assembly behavior of amphiphilic block copolymers at the liquid/liquid interface for the construction of hierarchical nanostructures and evaluation of emulsifiers. In this work, the adsorption and self-assembly of PS- b -PEO, a typical amphiphilic and temperature-sensitive block copolymer with abundant coordination sites were investigated by using a liquid/liquid interfacial assembly method in which pure water covered a chloroform solution of PS- b -PEO to form a planar liquid/liquid interface first, and then the aqueous solution of copper acetate was added dropwise into the water. It was found that spontaneous interfacial emulsification occurred when Cu2+ aqueous solution was added into the water at 28 °C. The PS- b -PEOs with shorter PEO chains self-assembled into hollow spheres, hierarchical hollow spheres, and hollow spheres with layered walls, depending on the relative length of the PEO blocks; while the PS- b -PEO with a longer PEO chain formed Janus sheets. While, PS- b -PEOs self-assembled into Janus sheets with monolayer or stepped multilayer structures at 18 and 8 °C through interfacial adsorption and assembly, regulated by the molecular structures. In addition, the concentrations of PS- b -PEO and Cu2+ ions also affect the self-assembly behavior and the aggregate morphologies. [Display omitted] • The liquid/liquid interfacial self-assembly of PS- b -PEOs was investigated. • They self-assembled into various hollow spheres at higher temperature. • The formation of hollow spheres was attributed to spontaneous emulsification. • They self-assembled into monolayer or multilayer Janus sheets at lower temperature. • The self-assembly behavior also depends on molecular structure and metal ions. [ABSTRACT FROM AUTHOR]

Large area of nanodot arrays of polystyrene- block -poly(2-vinylpyridine) (PS- b -P2VP) with inorganic species, including phosphotungstic acid, phosphomolybdic acid or transition metal ions have been fabricated at the planar liquid/liquid interface between pure water and chloroform solution of the block copolymers by adding the aqueous solution of the inorganic species dropwise into the water phase. The nanodots arrange into a quasi-hexagonal pattern, the area reaches to several hundreds of square microns, and the size of the nanodots and the distance between the nanodots can be tuned. The formation of the nanodot arrays is attributed to the interaction between the pyridine groups in the P2VP blocks and the inorganic species through electrostatic interaction or coordination that enhances the hydrophilicity of the block copolymers and leads to aggregation of the P2VP blocks during the adsorption and self-assembly process. This is a novel way to fabricate large area of ordered nanostructures. [Display omitted] [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]

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: Free-standing thin films of poly(2-vinylpyridine) (P2VP) doped with platinum complex ions were fabricated at the planar aqueous solution of H2PtCl6/chloroform solution of P2VP interface. The formation of the free-standing thin films was attributed to the adsorption and combination of the polymer molecules and the complex ions at the interface, and self-assembly of the composites. The films were composed of thin layers decorated with separated and conglutinated microcapsules. After treatment with KBH4 aqueous solution, the platinum complex ions incorporated in the polymer matrices transformed to platinum nanoparticles with the mean size of 2.2nm, which was confirmed by transmission electron microscopic investigations and X-ray photoelectron spectroscopic (XPS) analysis of the samples. Both the contents of the platinum element in the untreated and treated composite films estimated based on the thermagravimetric analysis (TGA) were close to each other, indicating no loss of platinum during the treatment process. The catalytic activity of the composite films was evaluated by using the reduction of 4-nitrophenol by KBH4 in aqueous solutions. The results indicated that the composite films have high and durable catalytic activity. [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]

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]