Nü Wang

Electrospun porous structure fibrous film with high oil adsorption capacity.

A low-cost, high-oil-adsorption film consisting of polystyrene (PS) fibers is fabricated by a facile electrospinning method. Different fiber diameter and porous fibers surface morphology play roles in oil adsorption capacity and oil/water selectivity. The results showed that oil adsorption capacity of PS oil sorbent film with small diameter and porous surface structure for diesel oil, silicon oil, peanut oil and motor oil were approximate to 7.13, 81.40, 112.30, and 131.63 g/g, respectively. It was higher than normal fibrous sorbent without any porous structure. The thinner porous PS oil sorbent also had excellent oil/water selectivity in the cleanup of oil from water.

Electrospinning of multilevel structured functional micro-/nanofibers and their applications

Electrospinning is a straightforward and versatile way to fabricate multilevel structured ultrafine fibers down to the micro-/nanometer scale. In this review, recent achievements in electrospun fibers with multilevel surfaces and inner structures are presented. The multilevel surface structures include branched structures, porous structures, necklace structures and non-cylinder deformed structures. The multilevel inner structures are classified as peapod structures, multiwalled tube structures, wire-in-tube structures and multichannel structures. Furthermore, the outstanding properties of multilevel structured fibrous materials are discussed and highlighted. These electrospun multilevel structured materials have wide applications in sensing, filtration and adsorption, catalysis, energy storage, bio-field, and many other fields.

Unidirectional water-penetration composite fibrous film via electrospinning

An interesting “water diode” film is fabricated by a facile electrospinning technique. The fibrous film is a composite of hydrophobic polyurethane (PU) and hydrophilic crosslinked poly (vinyl alcohol) (c-PVA) fibrous layers. By taking advantages of the hydrophobic–hydrophilic wettability difference, water can penetrate from the hydrophobic side, but be blocked on the hydrophilic side.

Fabrication of Hierarchically Porous Inorganic Nanofibers by a General Microemulsion Electrospinning Approach

One-dimensional nanostructured inorganic oxides have drawn considerable attention in recent years due to their excellent performance, which is superior to that of bulk materials. [ 1 ] Since the interior structure plays an important role in determining the material properties, various 1D nanomaterials with complex inner structures have been fabricated, such as hollow structures, [ 2 ] multilevel structures, [ 3 ] and many other special morphologies and shapes. In particular, much interest has been devoted to porous 1D nanomaterials [ 4 ]

Bioinspired Electrospun Knotted Microfibers for Fog Harvesting

Water is one of the most important substances in life. For most living creatures, water can be obtained from a readily available water source. However, for some others living far away from a water source, water collection becomes an important part of their lives. For example, in the dry Namib Desert, desert beetles live through collecting water from foggy air based on the micrometer-sized patterns of hydrophobic and hydrophilic regions on their backs. With special structures consisting of periodic spindle-knots, spider silks are also endowed with water collecting properties due to the directional moving of water drops from joints to spindle-knots. To adapt to living environment, natural creatures have evolved various elaborate biomaterials with superior performances. Learning from nature is thereby a shortcut for designing new functional materials. Realization of artificial fog-harvesting materials, which could collect water from humid air, will provide a potential outlet to relieve drought in dry areas. Inspired by desert beetles, a number of hydrophobic surfaces with alternative hydrophilic patterns that show fog-collection properties, have been developed up to now. However, the preparation of these materials is relatively cumbersome and costly, which obstructs their spread and application. In previous work, using a dip-coating method, we have fabricated a kind of knotted microfiber which is similar to spider silk in shape. Tiny water drops could be directionally moved and collected on the fiber. Comparing to plate materials, fabric fog-collection materials are undoubtedly more economical in terms of materials and more widely applicable. However, using the earlier method, only a limited length of fiber could be treated at a time. The fabrication of artificial water-collection fibers on a large scale is still challenging. Using electrohydrodynamics to stretch a viscous liquid into fibers (called electrospining) or break a dilute liquid into tiny droplets (called electrospray) has become an effective avenue to generate microscopic materials. Among diverse electrohydrodynamics products, beaded fibers, which are an intermediate state between electrospinning and electrospray products, are normally regarded as unwanted by-product to be avoided as far as possible. However, it has been noticed that the beaded fibers have a structure of periodic knots, which resembles the shape of natural spider silk to some extent. Although some researchers have investigated the fabrication of beaded fibers by electrospinning, few of them have paid attention to the functionality of the unique beaded structures. Recently, we have fabricated a kind of humidity-sensitive heterostructured beaded fiber by coaxial electrospinning. On such a beaded fiber, the main fiber is composed of polystyrene (PS), on which beads composed of polyethylene glycol (PEG) are dispersed. Since PEG is sensitive to water, those beads could reversibly swell and shrink in different humidity. However, this fiber is inapplicable for water collection because PEG is water-soluble. Herein, we fabricated a kind of knotted microfiber able to collect water. On this fiber, PS acts as supporting fiber on which balsam-pear-like poly(methyl methacrylate) (PMMA) knots are distributed. The spindle-knotted structure of this fiber endowed it a surface energy gradient between spindle-knots and joints. When tiny water drops condense on the fiber, they move directionally from the joints to spindle-knots in the same fashion as the water-collecting process on natural spider silk. The electrospinning fabrication of the knotted fibers provides an efficient and low-cost alternative for largearea preparation of water-collection fibers. Coaxial electrospinning (co-ESP) is a powerful approach to fabricate various microscopic core–shell or tubular fibers from various materials. In traditional co-ESP process, a highly viscous solution is used as outer solution in order to form a uniform liquid shell restricting the inner solution. It thus forms core–shell structured thin fibers after the composite liquid thread solidifies. This is a dynamic process in which the viscoelasticity must overwhelm the Rayleigh instability of the shell solution. If the Rayleigh instability cannot be overwhelmed, the thin liquid thread will fluctuate into knotted fiber or even break up into core–shell particles. Most of the earlier studies concentrated on the inhibition of Rayleigh instability in the coESP process to fabricate uniform fabric materials. Herein, however, we intend to employ the Rayleigh instability effect to generate spindle-knots on fibers. We used a viscous PS solution as inner solution, and a dilute PMMA solution as outer solution (Figure 1a). With co-ESP, the inner PS solution was stretched and formed fibers, and the outer PMMA solution flowed out with the inner solution and adhered to the surface of PS fiber. Because of the low concentration and low viscosity of PMMA solution, the liquid film formed a series of liquid drops induced by Rayleigh–Taylor instability before the solvent [a] Dr. H. Dong, Dr. L. Wang, Dr. H. Bai, Prof. L. Jiang Beijing National Laboratory for Molecular Sciences (BNLMS) Key Laboratory of Organic Solids Institute of Chemistry Chinese Academy of Sciences Beijing 100190 (P.R. China) E-mail : jianglei@iccas.ac.cn [b] Dr. N. Wang, Dr. J. Wu, Prof. Y. Zheng, Prof. Y. Zhao Key Laboratory of Bio-Inspired Smart Interfacial Science and Technology of Ministry of Education School of Chemistry and Environment Beihang University Beijing 100191 (P.R. China) E-mail : zhaoyong@iccas.ac.cn [c] Dr. H. Dong, Dr. L. Wang, Dr. H. Bai Graduate University of Chinese Academy of Sciences Beijing 100039 (P.R. China) Supporting information for this article is available on the WWW under http://dx.doi.org/10.1002/cphc.201100957.

Multicomponent phase change microfibers prepared by temperature control multifluidic electrospinning.

Multicomponent phase change microfibers, which can storage and release thermal energy in a stepwise manner, are firstly prepared through a facile one-step multifluidic compound-jet electrospinning with temperature control. The multiresponsive effect benefits from a special multichannel tubular microstructure that could controllably encapsulate different phase change materials into the channels independently. Aside from the fabrication of multicomponent phase change microfibers, the melt multifluidic compound-jet electrospinning is promising for applications related to microencapsulation and multifunctional material fields.

A Robust Cu(OH)2 Nanoneedles Mesh with Tunable Wettability for Nonaqueous Multiphase Liquid Separation.

The separation of organic liquid mixtures is achieved by Cu(OH)2 nanoneedle-covered copper mesh based on the difference of the liquid surface tension. The as-prepared membrane allows the penetration of organic liquid with smaller surface tension and blocks the higher. Thus, the effective separation of these two organic liquids can be achieved.

Polyaniline microtubes with a hexagonal cross-section and pH-sensitive fluorescence properties.

Polyaniline (PANI) microtubes with a hexagonal cross-section are successfully synthesized by a self-assembly process in the presence of 8-hydroxyquinoline-5-sulfonic acid (HQS) as a dopant and FeCl(3) as an oxidant. The wall thickness of the PANI/HQS microtubes can be adjusted by the content of the oxidant. It is proposed that the aniline/HQS salts serve as a hard template for the formation of the hexagonal-cross-section microtubes. Moreover, PANI/HQS microtubes combined with ZnSO(4) show pH-dependent fluorescence. PANI hexagonal-cross-section microtubes combined with a pH-sensitive fluorescence may promise potential applications in fields such as chemical sensors and confined reaction vessels.

Acrylic acid grafted porous polycarbonate membrane with smart hydrostatic pressure response to pH

A smart “pH-hydrostatic pressure responsor” is fabricated by plasma-induced graft polymerization. Acrylic acid was grafted onto a polycarbonate porous membrane. By taking advantage of the conformational changes of polyacrylic acid chains in acidic and alkaline solutions, the grafted membrane exhibits hydrostatic pressure variation and reversible conversion to pH.

High-flux, continuous oil spill collection by using a hydrophobic/oleophilic nanofibrous container

A hydrophobic/superoleophilic nanofibrous container was designed for the purpose of collecting oil spills. The device could continuously collect various kinds of oils from the surface of water and retain excellent stability when exposed to corrosive media. This work might provide a new strategy for designing fibrous membranes and applying them to the collection of oil spills.