聚苯乙烯蜂窝状多孔膜的制备及应用

以线性聚苯乙烯(PS)为膜材料,采用Breath Figures法制备了高度规整的蜂窝状结构多孔膜.研究了溶液浓度、环境湿度、气体吹扫速度及不同溶剂对多孔膜结构的影响.结果表明,相比于苯和二氯甲烷,氯仿作为溶剂因其挥发度适宜,PS浓度在20～80mg/mL的铸膜溶液可形成规整的蜂窝状结构多孔膜,且膜孔分布均匀、大小均一;制膜的湿度需高于环境湿度,但随着湿度的增加孔径增大;气体吹扫速度可在400～1000mL/min范围,但吹扫速度较大时孔径略有降低.该膜可作为固定诸如辣根过氧化酶等活性酶的载体,用于酶催化反应.     

Assembly of foam and honeycomb films of a diblock copolymer doped with Au or Ag nanoparticles at the liquid/liquid interface and their catalytic properties

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.     

Mesoscopic and submicroscopic patterning in thin polymer films: Impact of the solvent

Formation of mesoscopic and submicrometric self-assembled patterns in polystyrene and polycarbonate films produced by a fast dip-coating process was studied. Mixtures of chloroform and dichloromethane were used as a solvent. The mixture's composition plays a decisive role in the patterning. Close-packed honeycomb structures comprised of 200–2000 nm pores dispersed in polymer matrix were obtained. The mechanism of self-assembling is discussed.     

Breath Figures as a Dynamic Templating Method for Polymers and Nanomaterials

This review describes the use of breath figures as a templating method for the fabrication of self‐assembled polymeric‐ and nanoparticle‐based micro‐ and nanostructures. If moist air is blown over a solution of a polymer or stabilized nanoparticles in an organic solvent, such as carbon disulfide, benzene, or chloroform, evaporative cooling leads to the formation of water droplets on the liquid surface. The monodisperse droplets arrange into a hexagonal array and sink into the polymer solution. Removal of the solvent and the water leaves an imprint of the water droplets as a hollow, air‐filled, hexagonally ordered, polymeric bubble array. Progress in the field of breath‐figure formation is reviewed. The application of breath figures for the generation of functional structures in chemistry and materials science is discussed.     

水滴模板法制备蜂窝状结构多孔膜的研究进展

水滴模板法制备蜂窝状结构多孔膜是图案化表面技术领域的一大进展，其在生物技术、组织工程等领域有可能获得重要应用。综述了水滴模板法制备蜂窝状结构多孔膜的国内外研究进展，着重阐述了蜂窝状多孔膜的制作方法、形成机理及影响因素，同时指出了目前研究中存在的主要问题，并进一步提出了未来的研究发展方向。     

An overview of highly porous oxide films with tunable thickness prepared by molecular layer deposition

This paper is a short review about the principle, preparation, and applications of ultra-thin oxide films prepared by molecular layer deposition (MLD). Porous oxide films, with well-defined porous structures and precisely controlled thicknesses down to several angstroms, can be prepared from dense organic/inorganic hybrid polymer films grown by MLD. The organic constituents in the film can be removed either by calcination at elevated temperatures or mild water etching at room temperature. Because of the layer-by-layer growth process for MLD, the deposited polymer films have regular structures and the removal of organic components from MLD polymer films produces uniform interconnected highly porous structures with a high surface area. For example, porous aluminum oxide films prepared by such a method have both micropores and mesopores with a BET surface area as high as 1250 m²/g. Examples of the versatility of the technique for fabrication of novel functional materials for various applications are discussed, including thermally stable, highly selective metal nanoparticle catalysts, defect-free inorganic membranes for gas separation, and photocatalytic layers prepared from titanium alkoxide MLD films.     

Electronic Structure Evolution in Tricomponent Metal Phosphides with Reduced Activation Energy for Efficient Electrocatalytic Oxygen Evolution

Non‐noble metal catalysts for high‐active electrocatalytic oxygen evolution reaction (OER) are essential in large‐scale application for water splitting. Herein, tricomponent metal phosphides with hollow structures are synthesized from cobalt‐contained metal organic frameworks (MOFs), i.e., ZIF‐67, by tailoring the feeding ratios of Ni and Fe, followed by a high‐temperature reduction and a subsequent phosphidation process. Excellent OER activity and long‐time stability are achieved in 1 m NaOH aqueous solution, with an overpotential of 329 mV at 10 mA cm^?2 and Tafel slope of 48.2 mV dec^?1, even superior to the noble metal‐based catalyst. It is evidenced that the formed (oxyhydr)oxide/phosphate species by in situ electrochemical surface oxidation are responsible for active OER. Accordingly, the simultaneous introduction of external Ni and Fe elements significantly influences the electronic structures of the parent metal phosphides, leading to the in situ electrochemical formation of surface active layer with decreased OER activation energy for greatly improved water oxidation performance. This electronic structure tuning strategy by introducing multicomponent metals demonstrates a versatile method to use MOFs as precursors for synthesizing high‐efficient water splitting electrocatalysts.     

Preparation of Inorganic Materials Using Ionic Liquids

Conventional synthesis of inorganic materials relies heavily on water and organic solvents. Alternatively, the synthesis of inorganic materials using, or in the presence of, ionic liquids represents a burgeoning direction in materials chemistry. Use of ionic liquids in solvent extraction and organic catalysis has been extensively studied, but their use in inorganic synthesis has just begun. Ionic liquids are a family of non‐conventional molten salts that can act as templates and precursors to inorganic materials, as well as solvents. They offer many advantages, such as negligible vapor pressures, wide liquidus ranges, good thermal stability, tunable solubility for both organic and inorganic molecules, and much synthetic flexibility. In this Review, the use of ionic liquids in the preparation of several categories of inorganic and hybrid materials (i.e., metal structures, non‐metal elements, silicas, organosilicas, metal oxides, metal chalcogenides, metal salts, open‐framework structures, ionic liquid‐functionalized materials, and supported ionic liquids) is summarized. The status quo of the research field is assessed, and some future perspectives are furnished.     

Initial stages of deposition and film formation during spray pyrolysis — Nickel oxide, cerium gadolinium oxide and mixtures thereof

The formation of nickel oxide (NiO), cerium gadolinium oxide (CGO) and NiO-CGO thin films by air blast spray pyrolysis was studied at two scales. First, single droplets of precursor were deposited on sapphire substrates and the morphology of the formed residue was studied as a function of the substrate surface temperature, type of metal salt, salt saturation, and organic solvent in the precursor. Second, the synthesis of continuous films from repetitively deposited droplets and crack formation in the films were studied as a function of substrate temperature and salt decomposition kinetics. Nitrates, acetates, perchlorates and chlorides of nickel, cerium and gadolinium were the metal salts used, and mixtures of ethanol or water with di-, tri- and tetraethylene glycol were used as solvents.Regular ring- or disc-shaped deposits were formed from single droplets that evaporated without boiling and were mainly observed with metal acetate- and chloride-based spray solutions or at low substrate temperatures. Disc-shaped residues were obtained for saturated salt solutions and changed to rings with diminishing rim thickness with decreasing salt saturation. The formation of bubbles in the droplet from boiling or salt decomposition during evaporation resulted in the distortion of the circular shape and was predominantly observed for metal nitrate-based precursors and at high substrate surface temperatures.Continuous, dense and crack-free films of CGO and NiO-CGO with thicknesses up to 500 and 800 nm, respectively, were prepared from metal nitrate/chloride mixtures in a tetraethylene glycol-based solvent. The maximum crack-free thickness decreased with decreasing deposition temperature and was correlated to the metal salt decomposition kinetics.     

Bioinspired engineering of honeycomb structure – Using nature to inspire human innovation

Honeycomb structures, inspired from bee honeycombs, had found widespread applications in various fields, including architecture, transportation, mechanical engineering, chemical engineering, nanofabrication and, recently, biomedicine. A major challenge in this field is to understand the unique properties of honeycomb structures, which depended on their structures, scales and the materials used. In this article, we presented a state-of-the-art review of the interdisciplinary efforts to better understand the design principles for products with honeycomb structures, including their fabrication, performance (e.g., mechanical, thermal and acoustic properties) as well as optimization design. We described how these structural perspectives have led to new insights into the design of honeycomb structures ranging from macro-, micro- to nano-scales. We presented current scientific advances in micro- and nano-technologies that hold great promise for bioinspired honeycomb structures. We also discussed the emerging applications of honeycomb structures in biomedicine such as tissue engineering and regenerative medicine. Understanding the design principles underlying the creation of honeycomb structures as well as the related scientific discovery and technology development is critical for engineering bioinspired materials and devices designed based on honeycomb structures for a wide range of practical applications.     

高湿度条件下蜂窝孔结构的形成与控制

高湿度条件下规整蜂窝孔结构的形成是高分子分子自组装领域的一大进展,其在生物技术、组织工程、微图象技术、高端分离技术及医药等领域有可能获得重要应用．本文就高湿度条件下,规整蜂窝状孔结构的形成机理,制作方法,膜材质以及对蜂窝孔的形成与形态结构控制的影响因素等方面在近年来的研究进展进行了综述,对其正在进行的应用试验做了介绍,并对应用前景作了展望．     

Supersonic Cold Spraying for Energy and Environmental Applications: One-Step Scalable Coating Technology for Advanced Micro- and Nanotextured Materials

Supersonic cold spraying is an emerging technique for rapid deposition of films of materials including micrometer-size and sub-micrometer metal particles, nanoscale ceramic particles, clays, polymers, hybrid materials composed of polymers and particulates, reduced graphene oxide (rGO), and metal–organic frameworks. In this method, particles are accelerated to a high velocity and then impact a substrate at near ambient temperature, where dissipation of their kinetic energy produces strong adhesion. Here, recent progress in fundamentals and applications of cold spraying is reviewed. High-velocity impact with the substrate results in significant deformation, which not only produces adhesion, but can change the particles' internal structure. Cold-sprayed coatings can also exhibit micro- and nanotextured morphologies not achievable by other means. Suspending micro- or nanoparticles in a liquid and cold-spraying the suspension produces fine atomization and even deposition of materials that could not otherwise be processed. The scalability and low cost of this method and its compatibility with roll-to-roll processing make it promising for many applications, including ultrathin flexible materials, solar cells, touch-screen panels, nanotextured surfaces for enhanced heat transfer, thermal and electrical insulation films, transparent conductive films, materials for energy storage (e.g., Li-ion battery electrodes), heaters, sensors, photoelectrodes for water splitting, water purification membranes, and self-cleaning films.     

Fabrication of polymeric honeycomb microporous films: breath figures strategy and stabilization of water droplets by fluorinated diblock copolymer micelles

Polymeric honeycomb microporous films were prepared from fluorinated diblock copolymers, poly(tert-butyl acrylate)-b-poly(2-[(perfluorononenyl)oxy]ethyl methacrylate) (PtBA-b-PFNEMAs), and four other commercial polymers, including polystyrene (PS), polycarbonate (PC), polylactic acid (PLA), and polymethylmethacrylate (PMMA) via breath figures method. The as-formed fluorinated diblock copolymer micelles in chloroform were not only utilized to stabilize the templated water droplets in bulk, but also introduced as the water droplets stabilizer in other polymeric materials. Our strategy was successfully achieved, as the micropores were decorated with the fluorinated diblock copolymer as directly shown in the SEM images and FT-IR/ATR-FTIR. Polymer concentration and the solution casting volume effects were checked to tune the sizes of the micropores in diblock copolymer films. The ratio of the added fluorinated diblock copolymer as a novel factor to tune the sizes of the micropores was also investigated.     

水电站大坝金属结构物的防腐蚀措施及效果

水电站金属结构物受到大气、水、泥沙的腐蚀破坏,必须对其进行周期性检修和防腐蚀保护.以三峡 -葛洲坝水利枢纽实践为基础,介绍了水电站金属结构物防腐蚀保护方法以及金属层、有机涂料、无机涂料等防腐蚀材料的选用.在高速水流区金属结构物采用环氧金刚砂涂层、热喷碳化钨涂层及钛纳米聚合物涂层,水下金属结构物采用热喷锌层加有机涂料层封闭,大气环境下金属结构物采用环氧类涂料作底涂和丙烯酸聚氨酯涂料作面涂,都取得了比较好的防腐蚀效果.     

Rapid sonochemical preparation of shape-selective lead iodide

Lead iodide (PbI₂) films/crystals with various nano/micro morphologies (e.g., Nanoflake, block and microrod) were rapidly synthesized by taking advantage of a simple sonochemical method. The PbI₂ crystals with uniform nanoflake structures could be fabricated directly on lead foils with the irradiation time as short as 36 s via interfacial reaction between lead foils and elemental iodine in ethanol at ambient temperature. It was found experimentally that the morphologies of the resulting thin films/crystals could be well controlled by the adjustment of several parameters including irradiation time, reaction solvents, iodine concentration, ultrasonic power, and reaction temperature. Most importantly, the resultant PbI₂ films are stable enough to resist rolling under the drastic ultrasound irradiation in a liquid media. This method is believed to be the fastest way for in situ fabrication of morphology-controlled semiconductor films on various metal substrates for subsequent applications related to the other metal iodide or metal sulfide semiconductor films.     

Inhibiting the dissolution of zinc and magnesium alloys in acid emulsions

The mechanism of the corrosion-inhibiting action at the edges of printing elements during emulsion etching was studied. It was shown that surface-active substances (SAS) used as inhibitors in emulsion etching become adsorbed on zinc and magnesium alloys by a physical mechanism, i. e., due to electrostatic attraction of organic anions by positively charged metal surfaces. When alloys of this kind are in contact with an emulsion of a hydrocarbon in nitric acid containing SAS, polymolecular micellar adsorbed films of the SAS-hydrocarbon type are formed on their surface. In the case of low surface charges these films are mobile and, being shifted onto the edges of printing elements under the pressure exerted by the flow of an emulsion, inhibit their corrosion. High surface charges lead to the formation of dense immobile adsorbed films which inhibit the corrosion of the entire alloy surface.     

Organic Small Molecule Activates Transition Metal Foam for Efficient Oxygen Evolution Reaction

Developing low-cost, highly efficient, and durable electrocatalysts for oxygen evolution reaction (OER) is essential for the practical application of electrochemical water splitting. Herein, it is discovered that organic small molecule (hexabromobenzene, HBB) can activate commercial transition metal (Ni, Fe, and NiFe) foam by directly evolving metal nanomeshes embedded in graphene-like films (M-NM@G) through a facile Br-induced solid-phase migration process. Systematic investigations indicate that HBB can conformally generate graphene-like network on bulk metal foam substrate via the cleavage of C Br bonds and the formation of CC linkage. Simultaneously, the cleaved C Br fragments can efficiently extract metal atoms from bulk substrate, in situ producing transition metal nanomeshes embedded in the graphene-like films. As a result, such functional nanostructure can serve as an efficient OER electrocatalyst with a low overpotential and excellent long-term stability. Specifically, the overpotential at 100 mA cm⁻² is only 208 mV for NiFe-NM@G, ranking the top-tier OER electrocatalysts. This work demonstrates an intriguing general strategy for directly transforming bulk transition metals into nanostructured functional electrocatalysts via the interaction with organic small molecules, opening up opportunities for bridging the application of organic small molecules in energy technologies.     

Instantaneous formation of metal and metal oxide nanoparticles on carbon nanotubes and graphene via solvent-free microwave heating

Microwave irradiation was shown to be an effective energy source for the rapid decomposition of organic metal salts (such as silver acetate) in a solid mixture with various carbon and noncarbon substrates under completely solvent-free conditions. The rapid and local Joule heating of microwave absorbing substrates (i.e., carbon-based) resulted in the instantaneous formation of metal and metal oxide nanoparticles on the substrate surfaces within seconds of microwave exposure. Other less absorbing substrates (such as hexagonal boron nitride) required longer exposure times for the salt decomposition to occur. Details of the effects of microwave reaction time, temperature, power, and other experimental parameters were investigated and discussed. The solvent-free microwave method was shown to be widely applicable to various organic metal salts with different substrates including single- and multiwalled carbon nanotubes, graphene, expanded graphite, hexagonal boron nitride and silica-alumina particles, forming substrate-supported metal (e.g., Ag, Au, Co, Ni, Pd, Pt) or metal oxide (e.g., Fe?O?, MnO, TiO?) nanoparticles in high yields within short duration of microwave irradiation. The method was also successfully applied to large structural substrates such as nanotube yarns, further suggesting its application potential and versatility. To demonstrate one potential application, we successfully used both carbon nanotube powder and yarn samples decorated with Ag nanoparticles prepared via the above method to improve data acquisition in surface enhanced Raman spectroscopy.     

Assessment of semi-impregnated fabrics in honeycomb sandwich structures

Semi-impregnated fabrics, or semipregs, are fabrics alternating dry and resin impregnated areas along the fibre bed surface. Due to their increased initial through thickness permeability to gas flow, these could constitute an alternative to prepreg in the skins of vacuum-bagged honeycomb sandwich structures, reducing the pressure in the honeycomb. The semipreg through thickness air permeability before cure is measured and is approximately three orders of magnitude higher than that of a unidirectional prepreg impregnated with the same resin. A model is proposed for the air permeability change during cure, as dry areas get infiltrated. Due to resin pouring inside the honeycomb cells, this type of semipreg is viable as a skin only if combined with a material that has low permeability to resin, e.g., a prepreg.