Self-standing polyaniline film of mono-particle layer

Large, uniform and stable polyaniline (PANI) films were fabricated by ordering and drying polyaniline-coated-polystyrene (PANI-PS) latex microspheres. Particles on a glass substrate were highly ordered, closely packed and formed a two-dimensional lattice structure with the thickness of the diameter of the particle, 3.2 μm. Films fabricated on the substrate were peeled off by the pressure of water to yield the floating film, which could be transferred onto other substrates. One end of the film was connected to the platinum plate electrode while the other end was put in sulfuric acid. The film to which voltage was applied showed color change corresponding to the redox reaction. The voltammogram of the film showed the cathodic and the anodic peaks at 0.20 and 0.35 V versus SCE, respectively, being similar to peaks of electropolymerized PANI films. Films were inserted into tetrahydrofuran to remove the core-polystyrene. The resulting film had similar properties as polyaniline films of PANI-PS latex microspheres.     

Suppression of gold nanoparticle agglomeration and its separation via nylon membranes

Use of ultraporous nylon membrane is one of the most widely employed techniques for removal of hard and soft nanoparticles in the semiconductor industry,and the accurate determination of membrane pore size is necessary in order to avoid manufacturing defects caused by contamination.The gold nanoparticle has several benefits for the evaluation of polymeric membranes;however,the nanoparticles agglomerate easily on the nylon membrane and make it difficult to evaluate the membrane precisely.The properties of 2-amino-2-hydroxymethyl-1,3-propanediol (ADP) ligand in gold nanoparticle solution were systematically investigated,and ADP was utilized for improved evaluation of the nylon membranes.Nylon membrane used in this study was prepared by phase inversion techniques.Ultrathin dense layer on top of the membrane surface and Darcy structures in the microporous membrane support were observed.The gold particle rejection was carried out at various pH values from 4 to 14 and higher rejection was observed at pH 4 and 8.The suppression of gold colloid agglomeration using ADP and monodispersity of gold colloids was also analyzed by confocal laser scanning microscopy (CLSM),transmission electron microscopy (TEM),and scanning electron microscopy (SEM).van der Waals interaction energy of the particles was reduced in the addition of ADP.The presence ofADP ligand in the gold solutions prevented the agglomeration of gold nanoparticles and reduced the adsorption of the particles on the nylon membrane surface,leading to precise evaluation of membrane pore sizes.     

Resin-silica composite nanoparticle grafted polyethylene membranes for lithium ion batteries

To avoid the peeling-off of ceramic nanoparticles (NPs) from polyolefin membranes usually occurred in commercially available ceramic NPs coated polyolefin separators for lithium batteries, we propose a simple one-pot in-situ reaction method to modify commercial polyethylene (PE) separators by surface grafting 3-Aminophenol/formaldehyde (AF)/silica (SiO₂) composite NPs. The AF/SiO₂ composite NPs form self-supporting connected pores on the modified layer of the separator surface, which ensures the transportation of Li⁺. Moreover, the PE@AF/SiO₂ separators has higher electrolyte wettability and compatibility than neat PE separators attributed to the plentiful polar functional groups in the AF/SiO₂ layer and AF/SiO₂ composite NPs, resulting in higher lithium ion transference number (= 0.62) and ionic conductivity (σ = 0.722 mS cm⁻¹). More importantly, the discharge capacity, capacity retention rate and coulombic efficiency (136.2 mA h g⁻¹, 87.9% and 99%, respectively) after 200 cycles of Li|NMC half batteries with PE@AF/SiO₂ separators, are all more excellent than that with the pure PE separator (125 mA h g⁻¹, 83.1% and 85%, respectively). Our results show that the PE@AF/SiO₂ separators obtained by this modification method have higher electrochemical stability in the lithium battery system.     

超薄壁结构海藻酸钙胶囊膜制备及其功能化研究新进展

海藻酸钙胶囊膜由于具有制备过程温和环保、材料生物相容性优良等优点,广泛应用于生物医药等领域。薄壁结构的胶囊膜可减小跨膜传质阻力,加速囊膜内外物质的交换,因而备受学术界和工业界的广泛关注。近年来,具有超薄壁结构的海藻酸钙胶囊膜的制备与改性成为一个研究热点。本文综述了超薄壁结构海藻酸钙胶囊膜的制备方法及其功能化的研究新进展,重点介绍了利用共挤出毛细管装置制备超薄壁结构的海藻酸钙胶囊膜、利用精蛋白吸附与仿生硅化技术对超薄壁结构海藻酸钙胶囊膜的有机/无机杂化处理,以及利用复合纳米响应性凝胶颗粒的方法和接枝响应性聚合物高分子的方法实现超薄壁结构海藻酸钙胶囊膜的功能化改性等方面的研究现状。     

Alginate/protamine/silica hybrid capsules with ultrathin membranes for laccase immobilization

A novel type of core–shell capsules with ultrathin alginate/protamine/silica (APSi) hybrid membranes are successfully fabricated through a coextrusion minifluidic approach and a biosilicification method for immobilization of laccase. The ultrathin membranes were beneficial to the mass transfer across the capsule membranes, and the silica layer on the outer surface was efficient to inhibit the swelling of the capsule membranes. The immobilizing yield was considered to be 100% because all the enzyme molecules were encapsulated inside the capsules through the proposed method, and the laccase activity immobilized in APSi capsules was 61.8 mmol·g^–1·min^–1. The thermal, pH and storage stabilities of the immobilized laccase in APSi capsules were determined in comparison with free laccase. The stability of encapsulated laccase was significantly improved, which was as high as 67% after 20 days. The residual relative activity of encapsulated laccase remained 45% after 10 cycles. © 2012 American Institute of Chemical Engineers AIChE J, 59: 380–389, 2013     

PEO/聚吡咯中空纳米微球混合基质膜的制备及其CO2渗透分离性能

采用壳层具有介孔结构的聚吡咯中空纳米微球作为填料,和聚氧化乙烯单体共混自由基聚合制备了混合基质膜。结果表明,聚吡咯微球与基质相容性较好,未见明显团聚现象和缺陷。混合基质膜的渗透系数随填料含量的增加先增大后减少,在0.5%处达到最大值,CO₂渗透系数增长31%;CO₂/N₂分离系数有所降低,CO₂/CH₄分离系数则变化不大。研究表明,由于聚合物链段对微球壳层的介孔填充,气体在膜内的扩散系数不升反降,渗透系数的提高主要是由于溶解度系数的变化,而这也导致了溶解选择性的变化,进而影响了分离系数。     

Synthesis of PEO/hollow polypyrrole nanoparticle mixed matrix membranes for CO2 separation

The hollow polypyrrole nanoparticle with porous shell was incorporated into poly(ethylene oxide) monomer to fabricate the mixed matrix membrane by free radical polymerization. Morphology of the membranes showed the polymeric filler had good interfacial compatibility with the polymeric matrix without obvious defect. The results showed that the gas permeability of membranes increased at first and then decreased as the filler loading increased, while the permselectivity of CO₂/N₂ decreased_{andthat of CO2/CH4 maintained constant basically. The research showed that the diffusion coefficients decreased due to the blockage of the pore in shell of nanoparticles by polymeric matrix, the improvement of the gas permeability was mainly contributed by the improvement of the solubility coefficient, which also affected the solubility selectivity and then the permselectivity. The optimum nanoparticle loading was around 0.5%. In this case, the permeability of CO2 was about 6.5×10^-11 cm³?cm?cm^-2?s^-1?Pa^-1 (31% higher than the pristine polymeric membranes), while the permselectivity of CO2/N2 was about 30 (34% lower than that of the pristine polymeric membranes) and the permselectivity of CO2/CH4 was about 14 without significant sacrifice. The result showed the polypyrrole nanoparticles with porous shell was potential for application in CO2/CH4 separation.}     

Enhancement of corrosion protection of mild steel by chitosan/ZnO nanoparticle composite membranes

The development of active corrosion protection systems for metallic substrates is an issue of prime importance for many industrial applications. Nanostructured chitosan/ZnO nanoparticle films were coated on mild steel by sol–gel process, dip coating technique. Sol–gel protective coatings have shown excellent chemical stability, oxidation control and enhanced corrosion resistance for metal substrates. Further, the sol–gel method is an environmentally friendly technique of surface protection which has traditionally been used for increasing corrosion resistance of metals. Films so formed were characterized by UV–vis absorption spectroscopy (UV–vis), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and energy dispersive X-ray fluorescence spectrometry (EDX). Corrosion protection behavior of these coated mild steel substrates in 0.1 N HCl solutions was evaluated by potentiodynamic polarisation studies (Tafel), linear polarisation studies (LPR), electrochemical impedance spectroscopy studies (EIS).     

Self-standing piezoelectric nanogenerator fabrics from ZnO-doped PVDF nanofiber yarns

Today a wide variety of wearable electronics are in our daily lives and their uses are increasing. The development of portable, flexible, lightweight, cost-effective, and stable devices that produce sustainable energy with renewable approaches in the field of wearable electronics, as in every field, is one of the important issues of today. According to their volume and weight, the use of nanofibers with high surface area in energy-generating devices may bring them advantages such as lightness and higher energy density. Therefore, in recent years, researchers have focused on the development of nanofiber-based nanogenerators that produce energy using mechanical energy in a sustainable and renewable way. In this paper, self-standing piezoelectric nanogenerator (PENG) fabrics were obtained by developing flexible composite poly(vinylidene fluoride) (PVDF) nanofiber yarns doped with zinc oxide (ZnO) nanoparticles at different rates to provide higher power output. It has been characterized from electromechanical, structural, and morphological aspects. The most successful self-standing PENG fabric obtained (at 5% ZnO loading) doubled the energy output of the fabric made from pure PVDF nanofiber yarn and provided a peak total power of 81 μW and a power density of 30 μW/cm². The present results open up the field for the development of PVDF/ZnO-based nanomats and their use in sensors and actuators in the healthcare and engineering industries.     

Self-standing integrative cell with an inorganic separator for lithium-ion battery stacks

An integrative cell with a porous Al₂O₃ membrane as both a support and a separator has been fabricated. LiFePO₄ and graphite were coated onto the both sides of the rigid porous Al₂O₃ separator, while an electrolyte was infiltrated inside. The LiFePO₄/graphite integrative cells were evaluated in coin-type cells and exhibited good cycle capacity. The self-standing integrative cell was a simple and promising technology to assemble the battery stacks and meanwhile had an obvious advantage of forming a firm structure, which could avoid inner short circuit during being moved or crashed.     

Oxygen reduction and diffusion in electroactive nanostructured membranes (ENM) using a layer-by-layer dendrimer-gold nanoparticle approach

The fabrication of an electroactive nanostructured membrane (ENM) for oxygen reduction, made of layer-by-layer (LbL) films comprising Au nanoparticle-containing amine-terminated G4 PAMAM dendrimer alternated with poly(vinylsulfonic acid) (PVS) layers is reported. Electrochemical impedance spectroscopy and cyclic voltammetry show that electrodes with PVS/PAMAM-Au multiple bilayers are efficient for oxygen reduction and diffusion. A linear increase of oxygen reduction current occurs for up to 3 bilayers, with no further significant increase occurring for more than 3 bilayers. The 3-bilayer PVS/PAMAM-Au electrode, as an Au-ENM, is an attractive new system with potential for building diverse electrocatalytic devices with high molecular control.     

Polysulfone/zinc oxide nanoparticle mixed matrix membranes for CO2/CH4 separation

Preparation and characterization of novel polysulfone/zinc oxide (PSf/ZnO) mixed matrix membranes (MMMs) with different ZnO loadings for high selective CO₂/CH₄ separation were aimed in this study. Scanning electron microscopy photographs demonstrated that spongy and small tear like pores in plain PSf membrane (0 wt % of ZnO) replaced with large tear like pores close to surface layer by increasing ZnO content up to 0.1 and 1 wt %. In contrast, a dense and less free volume structure was obtained in membranes having 3 and 5 wt % of ZnO. Membrane porosity increased from 28.68 to 50.51% with increasing ZnO content from 0 to 1 wt %. Then, a reduction in porosity was observed for membranes containing 3 and 5 wt % of ZnO. Atomic force microscopy images presented variation in membrane surface roughness. Surface roughness decreased from 67.64 nm for plain PSf to 47.86 nm for membrane containing 1 wt % of ZnO. While, surface roughness increased and reached to 115.5 and 122.4 nm for MMMs having 3 and 5 wt % of ZnO. Gas separation properties of PSf/ZnO MMMs were examined and CO₂/CH₄ selectivity of MMMs containing 3 and 5 wt % of ZnO were 22.29 and 54.29, respectively, in 1 bar feed pressure. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39745.     

Self-standing Janus nanofiber heterostructure photocatalyst with hydrogen production and degradation of methylene blue

A highly efficient, stable, easily recyclable carbon-based [g-C₃N₄/C]//[TiO₂/C] Janus nanofibers heterostructure photocatalyst (gT-JNHP) was first designed and constructed through the combination of conjugative electro-spinning with subsequent calcination procedure. gT-JNHP with novel Janus structure consists of two sides: one side is g-C₃N₄/C nanofiber that absorbs visible light (VL), and the other side is TiO₂/C nanofiber that can capture ultraviolet light (UL), and the two strands of nanofibers are tightly combined together to form the unique heterostructure Janus nanofiber, which can make full use of sunlight (SL). gT-JNHP presents better remarkably boosted photocatalytic performance in comparison with the counterpart g-C₃N₄/C, TiO₂/C, or their mechanical mixture, and the degradation efficiencies of methylene blue in gT-JNHP-2, respectively, are 95.1% (160 min) and 98.6% (140 min), as well as hydrogen evolution rates reach up to 12.40 and 16.72 mmol h^–1 g^–1 under VL and simulated SL, respectively, thereby displaying the excellent dual functions of high-efficient hydrogen release and removal of organic contaminant. The outstanding photocatalytic property is ascribed to the joint effect among the unique Janus-typed heterostructure, catalyst components, and electrically conductive carbon fiber, achieving close contact between the interfaces, effective separation of photo-excited carriers, strong light capture ability, and many more exposed active sites, etc. Feasible photocatalytic mechanisms are advanced. Moreover, gT-JNHP owns the characteristics of flexible self-standing, easy recycling, and superb durability. The constructing mechanisms of Janus nanofibers and gT-JNHP are discussed in detail, and the novel fabricating techniques are established. The designing idea and construction techniques adopted in this paper are popularized for research and development of other peculiar uni-dimensional dual-functional nanofibrous photocatalysts.     

Separation of acid–water mixtures by pervaporation using nanoparticle filled mixed matrix copolymer membranes

BACKGROUND: Low energy and less expensive membrane based separation of acetic acid‐water mixtures would be a better alternative to conventional separation processes. However, suitable acid resistant membranes are still lacking. Thus, the objective of the present study was to develop mixed matrix membrane (MMM) which would allow high flux and water selectivity over a wide range of feed concentrations of acid in water. RESULTS: Three MMMs, namely PANBA0.5, PANBA1.5 and PANBA3 were made by emulsion copolymerization of acrylonitrile (AN) and butyl acrylate (BA) with 5.5:1 comonomer ratio and in situ incorporation of 0.5, 1.5 and 3 wt%, sodium montmorilonite (Na‐MMT) nanofillers, respectively. For a feed concentration of 99.5 wt% of acid in water the membranes show good permeation flux (2.61, 3.19, 3.97 kg m^?2 h^?1 µm^?1, for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) and very high separation factors for water (1473, 1370, 1292 for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) at 30 °C. Similarly for a dilute acid–water solution, i.e. for 71.6 wt% acid the membrane showed a very high thickness normalize flux (8.67, 9.44, 11.56 kg m^?2 h^?1 µm^?1, for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) and good water selectivity (101.7, 95.3, 79 for PANBA0.5, PANBA1.5 and PANBA3 membrane, respectively) at the same feed temperature. The permeation ratio, permeability, diffusion coefficient and activation energy for permeation of the membranes were also estimated. CONCLUSION: Unlike most of the reported membranes, the present MMMs allowed high flux and selectivity over a wide range of feed concentrations. These membranes may also be effective for separating other similar organic‐water mixtures. Copyright © 2012 Society of Chemical Industry     

Micro- and nanoparticle production by electrospraying

Electrospraying is a method of liquid atomisation by electrical forces. Droplets produced by electrospraying are highly charged, that prevents their coagulation, and promotes self-dispersion. Droplets can be extremely small, in special cases down to nanometers, and the charge and size of the droplets can be controlled to some extent by voltage and flow rate. Electrospraying is applied in many industrial processes such as painting, microencapsulation, electroemulsification, fine powder production, or micro- and nanothin film deposition prepared from solutions or colloidal suspensions. Recently, the electrospraying entered in microfluidic devices and nanotechnology. Spraying solutions or suspensions allows production of fine particles, down to nanometer size, which can be used in industrial processes or for research purposes. The paper reviews electrostatic methods for fine particles production.     

Inherent porous structure modified by titanium dioxide nanoparticle incorporation and effect on the fouling behavior of hybrid poly(vinylidene fluoride) membranes

The incorporation of nanoparticles (NPs) into a casting solution is a widely used practice for controlling the membrane fouling tendency, but the specific role of NPs in fouling control from an internal porous structure optimization has seldom been investigated. In this study, we evaluated the specific role of titanium dioxide (TiO₂)–NPs (Degussa P25) in mitigating membrane organic fouling. We prepared the membranes by tailoring the concentrations of the NPs well; this resulted in an optimized membrane microstructure consisting of fingerlike voids (beneath the skin layer of the membrane) and spongy voids (adjacent to the fingerlike voids). The NP incorporation induced the formation of spongy voids beneath the skin layer, and the increase in the NP concentration increased the formation of spongy voids. Moreover, surface images obtained by scanning electron microscopy, X‐ray photoelectron spectroscopy results, and contact angles confirmed that TiO₂–NPs were almost absent on the skin layer. Antifouling experiments were performed with a model organic foulant in two flow orientations [fingerlike voids facing the retentate (FVR) and spongy voids facing the retentate (SVR)]. The results show that the membrane fluxes in FVR decreased more than those in SVR. The membrane with 1.5 wt % TiO₂ operated in SVR exhibited the lowest flux decline; this suggested that spongy voids with TiO₂ exposure could mitigate fouling to a greater extent. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43265.     

Self-standing conductive ITO-silica nanofiber mats for use in flexible electronics and their application in dye-sensitized solar cells

For the realization of flexible electronics, we proposed a nonwoven mat of inorganic electrospun nanofibers (NFs) of amorphous silica that is flexible and heat-resistive as a candidate to replace a glass or plastic substrate. We attempted to add electrical conductivity using indium tin oxide (ITO) to create self-standing, nonwoven flexible mats completely composed of inorganic ceramic materials. Two methods were tested to make the ITO-silica NF mats: electrospun silica-NF mats drop coated by ITO and hybrid mats composed of ITO NFs and silica NFs fabricated by the dual-spinneret electrospinning technique. Our produced ITO-silica NF mats exhibited both mechanical flexibility and thermal stability, even after heat treatment at 450–650 °C. The sheet resistance was 15–113 Ω/sq. We attempted to apply the obtained nonwoven conductive mats to the flexible photoanode of dye-sensitized solar cells (DSSCs) and highlighted the problems in the existing application.     

Self-standing flexible cathode of V2O5 nanobelts with high cycling stability for lithium-ion batteries

Self-standing V₂O₅ nanobelt electrode free of binders, conductive carbon or current collectors was successfully prepared via a simple one-step hydrothermal reaction. The length of V₂O₅ nanobelts was up to several hundreds micrometers and the thickness was around 40 nm. Ultralong nanobelts as building blocks and internal voids provide a robust mechanical flexibility and shortened ion/electron transport pathway. The self-standing electrode delivered an initial specific capacity of 127.4 mA h g⁻¹ at a current density of 60 mA g⁻¹ and exhibited excellent cycling stability with capacity retention up to 89.8% after 200 cycles. The outstanding cycling performance can be attributed to the excellent network stability, shortened Li-ion diffusion pathway and the high surface area between electrolyte/electrode interfaces.