A vapor phase hydrothermal modification method converting a honeycomb structured hybrid film into photoactive TiO2 film

Modified Breath Figure Methods for the Pore-Selective Functionalization of Honeycomb-Patterned Porous Polymer Films

Recent developments in the field of the breath figure (BF) method have led to renewed interest from researchers in the pore-selective functionalization of honeycomb-patterned (HCP) films. The pore-selective functionalization of the HCP film gives unique properties to the film which can be used for specific applications such as protein recognition, catalysis, selective cell culturing, and drug delivery. There are several comprehensive reviews available for the pore-selective functionalization by the self-assembly process. However, considerable progress in preparation technologies and incorporation of new materials inside the pore surface for exact applications have emerged, thus warranting a review. In this review, we have focused on the pore-selective functionalization of the HCP films by the modified BF method, in which the self-assembly process is accompanied by an interfacial reaction. We review the importance of pore-selective functionalization, its applications, present limitations, and future perspectives.

Preparation of Hierarchical Highly Ordered Porous Films of Brominated Poly(phenylene oxide) and Hydrophilic SiO₂/C Membrane via the Breath Figure Method

Porous permeable films materials have very broad prospects in the treatment of sludge-containing waste water due to their large surface area and good microfiltration. In this work, highly ordered porous membranes have been prepared successfully on ice substrates using a poly(phenylene oxide) (BPPO)-SiO₂ nanoparticle (NP) mixture by the brePorous permeable films materials have very broad prospects in the treatment of sludge-containing waste water due to their large surface area and good microfiltration. In this work, highly ordered porous membranes have been prepared successfully on ice substrates using aath figure method. Based on the theory of Pickering emulsion system and capillary flow, particle assisted membrane formation was analyzed. Another two sorts of new membranes SiO₂/C membrane and hierarchical porous polymer (HPP) membrane, which were obtained by modification of the BPPO-SiO₂ membrane by calcination and etching, were set up in a further study. Their properties were investigated through the methods of scanning electron microscopy (SEM), fourier transform infrared spectrometry (FTIR), ultraviolet spectrum (UV), capillary electrophoresis (CE), contact angle, and water flux tests. All these results demonstrate that both surface hydrophilicity and fouling resistance of the membrane would be improved by using SiO₂ as a filler. The membranes with high permeability and antifouling properties were used for microfiltration applications.

An in situ vapour phase hydrothermal surface doping approach for fabrication of high performance Co3O4 electrocatalysts with an exceptionally high S-doped active surface

A vapour phase hydrothermal doping approach is developed to fabricate highly S-doped Co₃O₄ nanosheets as electrocatalysts for triiodide reduction in DSSCs.

Photoelectrochemical manifestation of intrinsic photoelectron transport properties of vertically aligned {001} faceted single crystal TiO2 nanosheet films

{001} faceted anatase TiO₂ nanosheet array films after calcination exhibited high photoelectrocatalytic activity toward water oxidation owing to superiorly intrinsic photoelectron transport properties of {001} faceted single crystal nanosheets.

Breath Figures of Nanoscale Bricks: A Universal Method for Creating Hierarchic Porous Materials from Inorganic Nanoparticles Stabilized with Mussel-Inspired Copolymers

High-performance catalysts and photovoltaics are required for building an environmentally sustainable society. Because catalytic and photovoltaic reactions occur at the interfaces between reactants and surfaces, the chemical, physical, and structural properties of interfaces have been the focus of much research. To improve the performance of these materials further, inorganic porous materials with hierarchic porous architectures have been fabricated. The breath figure technique allows preparing porous films by using water droplets as templates. In this study, a valuable preparation method for hierarchic porous inorganic materials is shown. Hierarchic porous materials are prepared from surface-coated inorganic nanoparticles with amphiphilic copolymers having catechol moieties followed by sintering. Micron-scale pores are prepared by using water droplets as templates, and nanoscale pores are formed between the nanoparticles. The fabrication method allows the preparation of hierarchic porous films from inorganic nanoparticles of various shapes and materials.

Porphyrin-based honeycomb films and their antibacterial activity

Micrometer-sized porous honeycomb-patterned thin films based on hybrid complexes formed via electrostatic interaction between Mn(III) meso-tetra(4-sulfonatophenyl) porphine chloride (an acid form, {MnTPPS}) and dimethyldioctadecylammonium bromide (DODMABr). The morphology of the microporous thin films can be well regulated by controlling the concentration of MnTPPS-DODMA complexes, DODMABr, and polystyrene (PS), respectively. The formation of the microporous thin films was largely influenced by different solvents. The well-ordered microporous films of MnTPPS-DODMA complexes exhibit a more efficient antibacterial activity under visible light than those of hybrid complexes of nanoparticles modified with DODMABr, implying that well-ordered microporous films containing porphyrin composition can improve photochemical activity and more dominance in applications in biological medicine fields.

Multiple interfaces in self-assembled breath figures

Progress in the breath figure method is reviewed by emphasizing the role of the multiple interfaces and the applications of honeycomb films in separation, biocatalysis, biosensing, templating, stimuli-responsive surfaces and adhesive surfaces.

Dispersion of Al2O3 nanoparticles stabilized with mussel-inspired amphiphilic copolymers in organic solvents and formation of hierarchical porous films by the breath figure technique

Hierarchical porous inorganic materials have attracted much attention, due to their large surface area and fast substance diffusion. We have prepared hierarchical porous films composed of Al2O3 nanoparticles (NPs) using the breath figure technique. The Al2O3 NPs were stabilized using an amphiphilic copolymer that contained catechol moieties. Porous films of polymer-stabilized Al2O3 NPs were prepared using water droplets as templates. The films were sintered to produce hierarchical porous Al2O3 films that were thermally and chemically stable.

Advances in Fabrication Materials of Honeycomb Structure Films by the Breath-Figure Method

Creatures in nature possess almost perfect structures and properties, and exhibit harmonization and unification between structure and function. Biomimetics, mimicking nature for engineering solutions, provides a model for the development of functional surfaces with special properties. Recently, honeycomb structure materials have attracted wide attention for both fundamental research and practical applications and have become an increasingly hot research topic. Though progress in the field of breath-figure formation has been reviewed, the advance in the fabrication materials of bio-inspired honeycomb structure films has not been discussed. Here we review the recent progress of honeycomb structure fabrication materials which were prepared by the breath-figure method. The application of breath figures for the generation of all kinds of honeycomb is discussed.

Morphology controlled fabrication and ferroelectric properties of vertically aligned one-dimensional lead titanate nanoarrays

Vertically aligned nanowires and highly uniform nanoporous array thin films of PbTiO(3) are synthesized by varying anodic oxidation conditions of Ti foil followed by hydrothermal reaction in an aqueous Pb(II) acetate trihydrate solution. As-synthesized samples have single crystalline nanowire structure and polycrystalline nanoporous structure, although both are pure PbTiO(3) with a tetragonal phase. The structure of intermediate TiO(2) films obtained from different anodic oxidation conditions determines the structure of the product PbTiO(3). The relationships between these morphological structures and ferroelectric properties are investigated. Piezoresponse force microscopy reveals that both these films show ferroelectricity with clear phase contrast and well-defined hysteresis loops. The saturated longitudinal piezoelectric coefficient field (E(c)) of the nanowire sample is smaller than that of nanoporous thin film. Thus, polarization of nanowire thin film is larger in magnitude and easier to flip than that of nanoporous film.

Self-assembly and morphology control of new L-glutamic acid-based amphiphilic random copolymers: giant vesicles, vesicles, spheres, and honeycomb film

New amphiphilic random copolymers containing hydrophobic dodecyl (C12) chain and hydrophilic L-glutamic acid were synthesized, and their self-assembly in solution as well as on the solid surfaces was investigated. The self-assembly behavior of these polymers are largely dependent on their hydrophilic and hydrophobic balances. The copolymer with a more hydrophobic alkyl chain (∼90%) self-assembled into giant vesicles with a diameter of several micrometers in a mixed solvent of ethanol and water. When the hydrophobic ratio decreased to ca. 76%, the polymer self-assembled into conventional vesicles with several hundred nanometers. The giant vesicles could be fused in certain conditions, while the conventional vesicles were stable. When the content of the hydrophilic part was further increased, no organized structures were formed. On the other hand, when the copolymer solutions were directly cast on solid substrates such as silicon plates, films with organized nanostructures could also be obtained, the morphology of which depended on solvent selection. When ethanol or methanol was used, spheres were obtained. When dichloromethane was used as the solvent, honeycomb-like morphologies were obtained. These results showed that through appropriate molecular design, random copolymer could self-assemble into various organized structures, which could be regulated through the hydrophobic/hydrophilic balance and the solvents.

Tunable assembly of nanoparticles on patterned porous film

This paper describes an approach to fully selective assembly of nanoparticles on patterned porous surface. Copolymers of polystyrene-block-poly(N,N-dimethylaminoethyl methacrylate) synthesized by atom transfer radical polymerization were used to prepare honeycomb-patterned porous films by the breath figure method. The regularity and pore size of the films can be modulated by changing the polymer composition and casting conditions such as concentration and airflow speed. Positively charged films were fabricated directly from the quaternized copolymers or by surface quaternization. X-ray photoelectron spectroscopy and adsorption of negatively charged fluorescein sodium salt confirmed the quaternization. Then assembly of negatively charged silica nanoparticles from its aqueous dispersion was performed. Results indicate that they assemble on the external surface of patterned porous films that without prewetting. For prewetted films, the nanoparticles assemble both on the external surface and in the pores. Poly(acrylic acid) deposited from its aqueous solution can serve as an effective blocking layer, which directs the selective assembly of nanoparticles into the pores, instead of the external surface of the film. It is concluded that the Cassie-Wenzel transition is the key to the selective assembly on the highly porous films. The well-defined selective assembly forms unique hierarchical structures of nanoparticles and greatly enlarges the diversity of structures of nanoparticle aggregates. This general approach also opens a straightforward route to the selective modification of patterned porous films.