Jingye Li

Salt‐Induced Fabrication of Superhydrophilic and Underwater Superoleophobic PAA‐g‐PVDF Membranes for Effective Separation of Oil‐in‐Water Emulsions

Conventional polymer membranes suffer from low flux and serious fouling when used for treating emulsified oil/water mixtures. Reported herein is the fabrication of a novel superhydrophilic and underwater superoleophobic poly(acrylic acid)-grafted PVDF filtration membrane using a salt-induced phase-inversion approach. A hierarchical micro/nanoscale structure is constructed on the membrane surface and endows it with a superhydrophilic/underwater superoleophobic property. The membrane separates both surfactant-free and surfactant-stabilized oil-in-water emulsions under either a small applied pressure (<0.3 bar) or gravity, with high separation efficiency and high flux, which is one to two orders of magnitude higher than those of commercial filtration membranes having a similar permeation property. The membrane exhibits an excellent antifouling property and is easily recycled for long-term use. The outstanding performance of the membrane and the efficient, energy and cost-effective preparation process highlight its potential for practical applications.

Ultra-light, compressible and fire-resistant graphene aerogel as a highly efficient and recyclable absorbent for organic liquids

Compressive graphene aerogels were obtained by the one-step reduction and self-assembly of graphene oxide with ethylenediamine and then freeze-drying. The aerogels hold good compressibility, variable electrical resistance and fire-resistance. The high porosity with a hydrophobic nature, allows the aerogels to absorb different organic liquids, and the absorption–squeezing process has been demonstrated for oil collection.

Laundering Durability of Superhydrophobic Cotton Fabric

www.MaterialsViews.com C O M Laundering Durability of Superhydrophobic Cotton Fabric M U N I By Bo Deng , Ren Cai , Yang Yu , Haiqing Jiang , Chunlei Wang , Jiang Li , Linfan Li , Ming Yu , Jingye Li ,* Leidong Xie , Qing Huang , and Chunhai Fan C A IO N A superhydrophobic surface, displaying a contact angle (CA) of water greater than 150 ° , [ 1 ] is a fascinating phenomenon in nature, which attracts not only academic but also industrial interest. It is well known that a superhydrophobic surface generally has a low surface energy chemical structure combined with a particular micro-structural roughness. [ 2 ] Using this principle, numerous superhydrophobic surfaces have been developed based on different materials using various methods and techniques, which have been reviewed recently. [ 3 ] There are many potential applications for artifi cial superhydrophobic surfaces in our daily life, among which waterproof textile is considered to be one of the most promising ones. [ 4 ] In this work, we report a convenient radiation-induced graft polymerization method to prepare an extremely stable, superhydrophobic cotton fabric, which is chemically stable over the entire pH range (0–14), and durable for more than 250 commercial or domestic launderings. Cotton fabric is widely used in daily life, it is a hydrophilic woven textile with numerous holes in its woven structure that make cotton fabric-based clothes comfortable. It is expected that a cotton fabric that is endowed with superhydrophobic properties, a so-called “superhydrophobic cotton fabric” (SCF), simultaneously possesses the properties of being waterproof as well as being air-breathing, which would lead to comfortable waterproof clothes. [ 5 ] In addition, because of the existence of air layers, its surface may not be wetted even upon full immersion in water, which makes it a good candidate for life vests. Because of the above-mentioned merits, many publications have been reported on the study of SCFs, which were mainly fabricated by doping of the cotton fabric with low surface energy nanoparticles. [ 6 ] However, the laundering durability, which is one of the most important characteristics for a fabric, has been largely ignored in these previous studies. Forming covalent bonds between cotton fi bers and low surface energy compounds is a critical point to enhance the stability of the SCF, and, as a consequence, should be the way to improve the laundering durability. [ 7 ] It is mainly the strength

Radiation induced reduction: an effective and clean route to synthesize functionalized graphene

Herein, we demonstrate that reduction of graphene oxide (GO) could be implemented by γ-ray irradiation in alcohol/water in the absence of oxygen. The resultant reduced GO (RGO) appears highly reduced and possesses high purity through UV-Vis, XPS, FT-IR spectra and elemental analysis. We speculate that production of reductive radicals from γ-radiolysis of solvents is the main mechanism for oxygen reducing and graphite restructuring of GO sheets. The control experiments show oxygen absence and alcoholic addition are the essential factors for reduction process, which correlated the production of reductive radicals with GOs reduction. Additionally, the investigation of resultant RGO papers solution-dispersibility and electrical conductivity indicates this method is favourable to build up graphene-based nanocomposites in solution.

A Robust Polyionized Hydrogel with an Unprecedented Underwater Anti-Crude-Oil-Adhesion Property

A polyionized hydrogel polymer (sodium polyacrylate-grafted poly(vinylidene fluoride) (PAAS-g-PVDF)) is fabricated via an alkaline-induced phase-inversion process. PAAS-g-PVDF coatings exhibit unprecedented anti-adhesion and self-cleaning properties to crude oils under an aqueous environment. A PAAS-g-PVDF-coated copper mesh can effectively separate a crude oil/water mixture with extremely high flux and high oil rejection driven by gravity, and is oil-fouling-free for long-term use.

Preparation of polymer decorated graphene oxide by γ-ray induced graft polymerization

Herein, we report a facile approach to decorate graphene oxide (GO) sheets with poly(vinyl acetate) (PVAc) by γ-ray irradiation-induced graft polymerization. The content of PVAc in the obtained sample, i.e., PVAc grafted GO (GO-g-PVAc) is calculated by the loss weight in thermogravimetric analysis (TGA) curves. A GO-g-PVAc sample with a degree of grafting (DG) of 28.5% was well dispersed in common organic solvents and the dispersions obtained were extremely stable at room temperature without any aggregation, even after standing for 2 months. The excellent dispersibility and stability of GO-g-PVAc in common organic solvents are readily rationalized in terms of the full coverage of PVAc chains and solvated layer formation on graphene oxide sheets surface, which weakens the interlaminar attraction of GO sheets. This approach presents a facile route for the preparation of dispersible GO and shows great potential in the preparation of graphene-based composites by solution-processes.

Laundering Durability of Photocatalyzed Self-Cleaning Cotton Fabric with TiO2 Nanoparticles Covalently Immobilized

Photocatalyzed self-cleaning cotton fabrics with TiO2 nanoparticles covalently immobilized are obtained by cograft polymerization of 2-hydroxyethyl acrylate (HEA) together with the surface functionalized TiO2 nanoparticles under γ-ray irradiation. The covalent bonds between the TiO2 nanoparticles and cotton fabrics bridged by poly(2-hydroxyethyl acrylate) (PHEA) graft chains is strong enough to survive 30 accelerated laundering circles, equivalent to 150 commercial or domestic launderings.

Preparation of the antifouling microfiltration membranes from poly(N,N-dimethylacrylamide) grafted poly(vinylidene fluoride) (PVDF) powder

Poly(vinylidene fluoride) (PVDF) powder is graft polymerized with N,N-dimethylacrylamide (DMAA) by a pre-irradiation induced graft polymerization technique. The existence of the graft chains in grafted PVDF (PVDF-g-PDMAA) powder has been proven by FT-IR spectroscopy and X-ray Photoelectron Spectroscopy (XPS) analysis. Then, the microfiltration (MF) membranes are prepared by isothermal immersion precipitation from PVDF-g-PDMAA powder in 1-methyl-2-pyrrolidone (NMP) solution from a water bath. The hydrophilicity of the MF membranes is determined by measuring the contact angles. The asymmetric morphology of the grafted membranes is studied by scanning electron microscopy (SEM), and water filtration properties are tested. The interaction between the membranes and proteins is studied by comparing the fluorescence microscopy images of these MF membranes cast from pristine PVDF and PVDF-g-PDMAA with a degree of grafting (DG) of 17.1% after surface fouling by Fluorescein Isothiocyanate (FITC)-conjugated Human Albumin solution. The antifouling property is determined by measuring the recovery percentage of pure water flux after the MF membranes have been fouled by bovine serum albumin (BSA) and lysozyme aqueous solution, separately. The results confirm that the existence of PDMAA graft chains improves the hydrophilicity and reduces protein adsorption of these MF membranes cast from PVDF-g-PDMAA powder.

Self-healing of the superhydrophobicity by ironing for the abrasion durable superhydrophobic cotton fabrics

Self-healing of the superhydrophobic cotton fabric (SCF) obtained by the radiation-induced graft polymerization of lauryl methacrylate (LMA) and n-hexyl methacrylate (HMA), can be achieved by ironing. Through the steam ironing process, the superhydrophobicity of the SCFs will be regenerated even after the yarns are ruptured during the abrasion test under a load pressure of 44.8u2005kPa. SCFs made from LMA grafted cotton fabric can ultimately withstand at least 24,000 cycles of abrasion with periodic steam ironing. The FT-IR microscope results show that the migration of the polymethacrylates graft chains from the interior to the surface is responsible for the self-healing effect.

Effect of a Room-Temperature Ionic Liquid on the Structure and Properties of Electrospun Poly(vinylidene fluoride) Nanofibers

Novel anti-static nanofibers based on blends of poly(vinylidene fluoride) (PVDF) and a room-temperature ionic liquid (RTIL), 1-butyl-3-methylimidazolium hexafluorophosphate [BMIM][PF6], were fabricated using an electrospinning approach. The effects of the RTIL on the morphology, crystal structure, and physical properties of the PVDF nanofibers were investigated. Incorporation of RTIL leads to an increase in the mean fiber diameter and the rough fiber surface of the PVDF/RTIL composite nanofibers compared with the neat PVDF nanofibers. The PVDF in the PVDF/RTIL nanofibers exhibits an extremely high content (almost 100%) of β crystals, in contrast to the dominance of PVDF γ crystals in bulk melt-blended PVDF/RTIL blends. Nonwoven fabrics produced from the electrospun PVDF/RTIL composite nanofibers show better stretchability and higher electrical conductivity than those made from neat PVDF without RTIL, and are thus excellent antielectrostatic fibrous materials. In addition, RTIL greatly improved the hydrophobicity of the PVDF fibers, enabling them to effectively separate a mixture of tetrachloromethane (CCl4) and water. The extremely high β content, excellent antielectrostatic properties, better stretchability, and hydrophobicity of the present PVDF/RTIL nanofibers make them a promising candidate for micro- and nanoscale electronic device applications.