Electrospinning of Porous Silica Nanofibers Containing Silver Nanoparticles for Catalytic Applicatio

Full Terms & Conditions of access and use can be found at/action/journalInformation?journalCode=tsta20Download by: [University Di Sassari]Date:03 February 2016, At: 07:47Science and Technology of Advanced MaterialsISSN: 1468-6996 (Print) 1878-5514 (Online) Journal homepage: /loi/tsta20Technological advances in electrospinning of nanofibersWee-Eong Teo, Ryuji Inai & Seeram RamakrishnaTo cite this article: Wee-Eong Teo, Ryuji Inai & Seeram Ramakrishna (2011) Technological advances in electrospinning of nanofibers, Science and Technology of Advanced Materials,12:1, 013002To link to this article:/10.1088/1468-6996/12/1/11660944© 2011 National Institute for MaterialsSciencePublished online: 12 Jan 2016.Submit your article to this journalArticle views: 12View related articlesCiting articles: 3 View citing articlesIOP P UBLISHINGS CIENCE AND T ECHNOLOGY OF A DV ANCED M ATERIALSSci.Technol.Adv.Mater.12(2011)013002(19pp)doi:10.1088/1468-6996/12/1/013002TOPICAL REVIEWTechnological advances in electrospinning of nanofibersWee-Eong Teo 1,2,Ryuji Inai 3and Seeram Ramakrishna 1,41Department of Mechanical Engineering,National University of Singapore,Singapore 117576,Singapore 2Biomers Pte Ltd,18Boon Lay Way,Singapore 609966,Singapore 3MECC Co.Ltd,Fukuoka 838-0137,Japan 4King Saud University,Riyadh 11451,Kingdom of Saudi Arabia E-mail:weeeong@Received 9September 2010Accepted for publication 6December 2010Published 16February 2011Online at /STAM/12/013002AbstractProgress in the electrospinning techniques has brought new methods for the production and construction of various nanofibrous assemblies.The parameters affecting electrospinninginclude electrical charges on the emerging jet,charge density and removal,as well as effects of external perturbations.The solvent and the method of fiber collection also affect theconstruction of the final nanofibrous architecture.Various techniques of yarn spinning using solid and liquid surfaces as well as surface-free collection are described and compared in this review.Recent advances allow production of 3D nanofibrous scaffolds with a desired microstructure.In the area of tissue regeneration and bioengineering,3D scaffolds should bring nanofibrous technology closer to clinical applications.There is sufficient understanding of the electrospinning process and experimental results to suggest that precision electrospinning is a real possibility.Keywords:nanofiber,3D structure,mass production,hierarchical organization1.IntroductionTechnological advances over the last few decades have resulted in the realization of several competing processes for fabricating nanometer-size objects.The development of nanolithography through the improvement of traditional microfabrication methods has enabled the construction of precise nanocircuits,while melt blowing can be used to mass-produce nanofibers.Although these technologies are excellent in their specific application domains,electrospinning has emerged as a popular nanotechnology since the late 1990s owing to the ease of fabricating nanofibers from a wide selection of materials.Researchers have explored the usage of electrospun nonwoven membranes in applications such as tissue engineering,energy,water filtration,biotechnology and sensors [1].In particular,this random mesh of nanofibers is suitable for air filtration because many commercial microfibrous membranes are already in nonwoven forms.Intissue engineering,early studies were mainly on interactions between cells and nanofibers,and little attention was paid to the structure of the substrate.Preliminary investigations into using nanofibers for other applications were not concerned with fiber arrangements.Nevertheless,it soon became apparent that ordered nanofibrous structures could outperform disordered ones.For example,cells cultured on aligned nanofibers become aligned in the direction of the fibers [2].Other researchers are also beginning to look into fabricating hierarchically organized and multifunctional nanofibrous structures [3].As new applications are found and new materials are electrospun into nanofibers,the need to understand current developments in nanofibrous structures to realize their potential has become increasingly important.Most research on electrospun nanofibers and industrial applications has been restricted to nonwoven membranes;however,this technology is leading to the generation of more elaborate1468-6996/11/013002+19$33.001©2011National Institute for Materials Science Printed in the UKD o w n l o a d e d b y [U n i v e r s i t y D i S a s s a r i ] a t 07:47 03 F e b r u a r y 2016structures.Understanding the electric field profile and its effect on the electrospinning jet has resulted in new ways of ordering nanofibers.Mechanical methods,such as those using rotating drums,disks and moving platform collectors,and simple manipulation of the electric field have been successfully used to fabricate membranes with ordered nanofibers.Details of these methods have been covered in our previous review [4].Recent studies of this technology have led to greater understanding and emphasis on fabricating commercially viable and more ordered structures.Yarns and three-dimensional (3D)scaffolds have been constructed using electrospinning.A few companies such as Donaldson and Finetex have been using electrospun nanofibers in their products but much of the science and technology behind their ability to mass-produce electrospun nanofibers remains a trade secret.The difficulty of mass-producing nanofibers by electrospinning becomes apparent from reading academic reports.Air filtration is one of the early applications of this technology as it only requires a thin nanofibrous layer (2to 3nanofibers thick)to achieve a significant improvement in performance and justify the relatively high production cost.More efficient electrospinning setups and fiber organization are needed to enhance the productivity of this technology,which may potentially rival conventional nanolithography owing to the steady improvements in the production rate and the control of the electrospinning jet to obtain ordered structures.In this review,we focus on recent developments in electrospinning designs and nanofibrous assemblies,in particular,the mass production of nanofibers,nanofibrous yarn fabrication,3D scaffold fabrication and precision electro-spinning.Some basic parameters that govern electrospinning design and the fabrication of nanofibrous assemblies are also introduced.2.Electrical chargesElectrospinning is based on inducing static electrical charges on the molecules of a solution at such a density that the self-repulsion of the charges causes the liquid to stretch into a fiber in an electric field [5].Provided there is no breakage in the stretched solution,a single strand of continuous fiber is formed upon solvent evaporation.When a high voltage is applied to the solution,the ohmic current distributes the charges throughout the molecules.As the solution is ejected from the spinneret tip,the ohmic current transits to a predominantly convective current [6].The charges are transported from the electrospinning tip to the target through the deposition of the fiber [7].The current stops oscillating when the deposition becomes stable.This can be used to monitor the spinning process [8].The electrical charges used for electrospinning can be positive,negative or both (alternating current)[9–12].Although most reported electrospinning experiments were carried out using a positive potential,it has been shown that a negative potential produces nanofibers with a narrower diameter distribution.This was explained by the fact that electrons can be dispersed more rapidly and uniformly than the much heavier protons [13].2.1.Solution delivery design (overcoming surface tension )In a typical electrospinning setup,a high-voltage source is connected to a metallic needle,which is attached to a solution reservoir.The needle has a relatively small orifice that concentrates the electric charge density on a small pendant drop of solution [14].Although a metallic spinneret such as a needle is convenient for the application of charge to the solution,the process also works if a high voltage is applied to the solution using a dedicated electrode with a nonconducting spinneret [14].A porous cylinder [15]has also been used for electrospinning,and it is possible to induce charges on a free solution droplet without direct contact to form a fiber [13,16,17].The theoretical modeling of a viscous leaky dielectric solution subjected to a critical voltage showed that it becomes unstable in an electric field when the surface tension can no longer maintain its static equilibrium [18].At this voltage,protrusions form on the solution surface and jets of solution are ejected.Any perturbation or nonuniformity on the solution surface will concentrate charges in regions with higher curvature.If the curvature is sufficiently large for the potential difference between such a region and the collector to reach a critical value,the solution erupts from the surface and accelerates towards the collector [19].This has given rise to numerous designs in which drums [20,21],spikes [22],ridges [23]and disks [21]have been used to dispense the solution for electrospinning.He et al [24]demonstrated that bubbling air in the solution and the subsequent disruption on the solution surface can initiate electrospinning at a reduced voltage.2.2.Charge density on electrospinning jetThe voltage supplied to the solution determines the charge density on the electrospinning jet—when the charge density is too high,the jet becomes highly unstable.Conversely,when the charge density is too low,the solution drips.Thus,there is an optimum voltage for stable spinning without any surface perturbations in the conical base region of the solution [25].At the initiation of electrospinning,the interaction between the electric field and the surface charges on the jet causes the liquid to accelerate towards the collector.Disregarding the viscosity and stiffness of the solution,a higher charge density on the jet causes greater instability [26,27].In a perfect dielectric jet,the nonuniformity in the radius of the jet along its length results in surface charges accumulating on the protruding regions.The self-repulsion of the charges tends to destabilize the jet,while tangential stress acting parallel to the flow tends to stabilize it.At a high charge density,the self-repulsion exceeds the stabilizing tangential stress resulting in bending instability [28].The bending instability may become so chaotic that loops of single jet merge into a cross-linked network.The series of close loops may constrain the motion of the electrospinning jet and form a fluffy cylindrical column with a diameter of a few millimeters [29].As the voltage increases,the increased charge density reduces the fiber diameter as the jet becomes stretched under a greater force;however,above an optimal voltage,the diameter 2D o w n l o a d e d b y [U n i v e r s i t y D i S a s s a r i ] a t 07:47 03 F e b r u a r y 2016starts to increase [30].This has been attributed to more material being drawn from the Taylor cone under increasing field strength and number of charges on the jet [31].2.3.Electrical discharge/neutralizationIn electrospinning,an electrically earthed collector is often used to collect the nanofibers.However,since the deposited nanofibers are typically nonconductive,residual charges build up as the nanofiber layer becomes thicker.This has several side effects such as creating a repulsive force which diverts the jet to other regions,nonuniform packing density,adhesion between layers of nanofibers and disruption of the nanofiber organization in cases where ordered patterns are desirable.A deionizer is an effective way of quickly removing charges from the electrospinning jet.However,it must be placed at an appropriate distance so that the charges are removed only when the fibers are sufficiently stretched and are relatively dry.Otherwise,beaded fibers may form if the electrospinning jet is discharged prematurely [32].Furthermore,a discharged electrospinning jet cannot be controlled using auxiliary electrodes.3.External effects3.1.External forces on the spinning jet3.1.1.Electrical force.The effect of the electric field profile around the electrospinning jet has been studied by many researchers.The charges on the electrospinning jet allow its path to be altered by an electric field.In a basic electrospinning setup,the polarity and strength of the voltage applied to both the spinneret and the collector can be varied.In more complex setups,auxiliary electrodes can be added,which have been used to control the deposition location and area [33]of the electrospun fiber,aligning nanofibers [34,35]and forming simple patterns [36].The auxiliary electrodes can be divided into the base electrode,steering electrodes,focusing electrodes,the collector and guiding electrodes as shown in figure 1.The base electrode is usually a conductive plate,which creates a uniform background electric field between the spin-neret and the collector;without a base electrode,the electric field can be affected by surrounding objects.The chaotic motion of the electrospinning jet may also veer off owing to the effect of this electric field.Yang et al [26]showed that the addition of a base electrode resulted in fibers with smaller diameters and a longer stable jet.An important consideration when a base electrode is used is the protrusion of the spinneret tip from the base electrode.If the spinneret tip is retracted into the base electrode,spinning may not occur at the same voltage.In contrast,when a conducting spinneret tip protrudes about 1cm from the base electrode,the fringe field at the spinneret tip may locally exceed the average field between the base electrode and the collector,and spinning will be initiated [37].A disadvantage of using a base electrode is that a higher applied voltage is required to initiate spinning [26].The function of the focusing electrodes is to damp the chaotic motion of the electrospinning jet so thatfiberFigure 1.Auxiliary electrodes for altering the electric field profile.deposition is more localized.They can be shaped as a ring,cylinder or cone and are usually placed close to the spinneret tip so that damping is more effective [38–40].Multiple focusing electrodes have also been used to reduce the spread of the fiber [33].As a type of focusing electrode,Salim et al applied a gold-coated polydimethylsiloxane mask with holes 400µm in diameter to repel fibers from its surface and direct them through the holes and onto a collecting substrate.The authors were able to collect patches of randomly oriented nanofibers on the substrate and restrict the deposition area of each nanofiber patch to a circle with diameter less than 200µm [41].Using the ability to focus the electrospinning deposition onto a small spot,patterns composed of randomly ordered nanofibers can be fabricated by moving the collector plate [38].However,as the electrospinning jet moves at a high speed,it may not be realistic to match the speed of the collector to that of the electrospinning jet to form ordered nanofiber patterns.Therefore,an alternative method is to use steering electrodes to direct the deposition of nanofibers.Depending on the complexity of the nanofiber pattern to be fabricated,steering electrodes may consist of two or more electrodes [36,39,42].A single parallel electrode system allows control only along a single axis and has been successfully used to fabricate aligned nanofibers [42].However,multiple pairs of electrodes are required to form more complex patterns.Only simple patterns,such as a square made of nanofibers,have been fabricated using steering electrodes thus far [36].Nevertheless,more complex patterns may be possible using the above concept.The collector itself can play an important role in the deposition of nanofibers.Through the use of a knife-edge disk collector,Theron et al [43]demonstrated that a grounded knife-edge guides the electrospinning jet toward it.Other researchers have used collectors with grids [44–47]or charged needles [48]to create patterned nanofibrous membranes as shown in figure 2.These patterned nanofibrous meshes consist of regions of high fiber density;the potential and fiber density were lower in insulated regions.3D o w n l o a d e d b y [U n i v e r s i t y D i S a s s a r i ] a t 07:47 03 F e b r u a r y 2016Figure 2.Collector grids made of selectively charged needles showing (a)the location of charged needles and (b)the corresponding nanofiber deposition.(Reproduced with permission from [48]©2009IOP Publishing.)The positioning of the collector also affects fiber deposition.When two conducting collectors are placed in parallel as shown in figure 3,it is possible to collect highly aligned nanofibers.The arrangement of parallel electrode collectors with a gap or insulating section between the electrodes creates an electric field profile that forces the charged nanofiber to span the gap [35].Li et al demonstrated that there is a maximum gap size above which the nanofibers are broken (>1cm for nanofibers thinner than 150nm).They hypothesized that this was due to the inability of a nanofiber to support its own weight beyond a certain length [35].Beachley and Wen showed that increasing the polymer solution concentration and the size of the plate collector allowed the gap [49]to be increased to 35–50cm for aligned fibers with a diameter of 350nm to 1µm.Liu and Dzenis demonstrated that increasing the gap distance improves the alignment of the nanofiing polyethylene oxide solution,aligned fibers were obtained with a gap of 18cm [34].Ishii et al used this method to control the number of nanofibers across plates by switching the polarity of the charges on them.Assuming that the electrospinning jet was positively charged,one of the plates was first given a negative charge so that nanofibers were deposited on it.The other plate was then charged negatively to lay a single nanofiber strand across the gap to the other plate.The number of nanofibers spanning the gap could be controlled by varying the number of times the polarity was switched [50].The success and simplicity of using the parallel electrode collector principle has generated various modifications to obtain different nanofiber assemblies.Arrays of nanofibers have been fabricated by employing multiple pairs of electrodes [51].A pair of aligned blades allows nanofibers to form aligned bundles across the gap between the blades [52].Depositing the fibers in a gap between two ring collectors [53]or a ring collector and a needle [54],and then applying a twist to one of the collectors while keeping the other end stationary gives rise to a twisted nanofiber bundle.However,there are still various critical shortcomings in this setup.The build-up of residual charges as nanofibers are deposited across the gap reduces the attractive strength of the electrodes andcausesFigure 3.Deposition of aligned nanofibers over a parallel electrode collector system.fiber misalignment [34,55],thus limiting the thickness of aligned nanofibers that can be obtained.Another significant drawback is that most nanofibers are randomly deposited on the electrode surface instead of spanning the gap.Thus,the productivity of this method is very low compared with other methods of fabricating aligned nanofibrous membranes.The attempts to increase the productivity of the parallel electrode system to obtain aligned nanofibers are summarized in table 1.When parallel electrodes are rotated as in cases (a and b)in table 1,the spacing between the electrodes causes air turbulence at high rotation speed,which disrupts the fiber deposition.This contrasts with mechanical drawing methods for achieving fiber alignment where a higher rotation speed is preferred.Since steering electrodes and a charged collector are both effective in directing the deposition of electrospun nanofibers,Acharya et al [42]have demonstrated that the combination of both techniques results in fibers with much better alignment.The electrospinning jet is sensitive to small differences in the electric field,and a wire placed below a glass slide has been shown to attract significantly more nanofibers onto the4D o w n l o a d e d b y [U n i v e r s i t y D i S a s s a r i ] a t 07:47 03 F e b r u a r y 2016Table 1.Electrospinning setups based on parallel electrode collector principle to increase aligned fiber productivity.Multiple parallel electrodes used to collect (a)aligned nanofibers [55].Multiple parallel electrodes used to collect (b)aligned nanofibers [56].A dual collector system with a stationary electrode placed above a moving belt causes fibers to align themselves between the topelectrode and the moving belt below.As the belt moves,the nanofibers are pulled off the electrode (c)above and are aligned on the belt below [57].glass surface directly above the wire [4].Therefore,a guiding electrode may be employed below the collector to direct the motion of the electrospinning jet.Teo et al [58]demonstrated that through the use of a knife-edge guiding electrode,the electrospinning jet can be directed to form aligned nanofibers at a desired angle on a tube.A guiding electrode in the form of a sharp tip has also been successfully used to create a nanofibrous grid [59–61].Wu et al used a combination of like-and oppositely charged guiding electrodes behind a rotating rod to guide the deposition of nanofibers within a narrow band.The presence of multiple guiding electrodes also enhanced fiber alignment compared to when a single guiding electrode was used to attract the electrospinning jet [62].3.1.2.Magnetic field.Theoretically,magnetic field can affect the spinning jet.Wu et al [63]suggested that the current carried on the jet as it travels in a spiral motion in a magnetic field creates a force towards the initial equilibrium point,thereby reducing the radius of the spiral;however,this has not been verified experimentally.Nevertheless,Ajao et al demonstrated fiber alignment on one face of a box made fromsilicon wafers with a cylindrical magnet inside.As shown in figure 4,the nanofibers were aligned in the direction of the electrospinning jet on the x –z -plane while nanofibers on all other faces were randomly aligned.It was suggested that this was due to the interaction of the electrospinning jet current in the y –z -plane,the magnetic field line along the y -axis caused a resultant force on the nanofibers in the x -direction [64].3.1.3.Gas-assisted effect.In some cases,electric charges alone may be insufficient to stretch the solution to form fibers.This may be due to the high viscosity and/or high surface tension of the solution.If volatile solvents are used,exposure to the environment and rapid evaporation of the solvent may render the solution unspinnable [65].Thus,to facilitate the electrospinning process,a gas jacket that blows and exerts a stretching force on the solution can be applied at the spinneret tip as shown in figure 5.Um et al .used a gas jacket to electrospin hyaluronic acid that has a very high viscosity.Fiber fabrication can be improved by using a heated gas,as the higher temperature reduces the viscosity of the solution [66].To electrospin solutions requiring a high temperature,such as ultrahigh-molecular-weight polyethylene solution,a heated5D o w n l o a d e d b y [U n i v e r s i t y D i S a s s a r i ] a t 07:47 03 F e b r u a r y 2016Figure 4.Cylindrical magnet boxed in silicon wafers.Aligned nanofibers are deposited on the top face of the box as shown in the figure.Random fibers covered all other faces of thebox.Figure 5.Design of spinneret for gas-jacket-assisted electrospinning.gas jacket may stabilize the solution at the tip of the spinneret and facilitate the process [67].Blowing a gas on the electrospinning jet can also be used to alter the nanofiber deposition.Varesano et al used the setup shown in figure 6to disrupt the motion of the electrospinning jet by creating an air vortex where the spinning was carried out.As nanofibers are very light,they were transported by the air vortex and deposited as crimped fibers [68].3.2.Collection techniques and manipulation of nanofibers We have discussed the effects of applying external pertur-bations such as an electric field profile,magnetic forces and gas-jacket-assisted stretching on the electrospinning jet and how they affected the spinnability and fiber deposition.However,controlling the electrospinning jet alone generally yields only two-dimensional meshes made of either random or aligned nanofibers.The fabrication of more complex structures,such as those shown in figure 7,requires other nanofiber collection techniques.These techniques are oftencombined with methods to control the electrospinning jet as discussed in the earlier sections.Tubular nanofibrous structures can be constructed by electrospinning directly over a rotating rod,and their hybrids (figure 8)can be fabricated through the clever use of molds to collect nanofibers [47].More discussion on mechanical rotating devices for collecting nanofibers can be found in our review [4].The processing method used for the mechanical organization of the nanofibers can be separated,continuous or integrated.In separated processing,a nanofibrous mesh is first fabricated and then processed into its final form.The advantage of this system is that intermediate modifications can be made before assembling the final form.For example,an aligned nanofiber mesh can be rolled onto a rod [69]before randomly oriented nanofibers are deposited over its outer surface.This method has also been used to seed cells on a nanofiber mesh before stacking them to form a 3D scaffold with uniformly distributed cells [70–72].Continuous processing involves concurrent nanofiber mesh formation and arrangement into its final form.In an example of this method,water was used as an intermediate supporting substrate for the collection of the nanofiber mesh.The fluid nature of water allows easy assembly of the deposited mesh into a yarn [73–75]or a 3D nanofibrous scaffold [76]without breaking the fibers.A solid substrate has also been used to collect a nanofiber mesh and concurrently drawing it into a yarn [77,78].Nanofiber clumps can be formed in the air and then drawn into other structures [79–81].Finally,electrospinning can be used in combination with other fabrication techniques as an integrated system.This process generally requires some form of scaffolding on the nanofiber while it is being deposited [82–84]such as by using a rapid prototyping technique [82,85–87].This method is often used to construct 3D structures as discussed below.4.Solution and materials propertiesSolution properties have been investigated as a means of controlling fiber characteristics such as diameter and morphology.However,this is one of the least explored parameters in the construction of nanofibrous assemblies.In addition to the electric field,it is also important to consider how solution and material properties may affect the assembly of more complicated nanostructures.The use of a solvent,polymer and/or additives with higher conductivity invariably affects the bending instability of the electrospinning jet.The addition of single-wall carbon nanotubes or salt added into the solution has been shown to create a more chaotic jet motion [29],thus encouraging the formation of nanofibrous tufts in mid-air,which can be drawn into a yarn [79,88].Similarly,loosely formed fibers on a solid substrate may also facilitate the drawing of fibers into yarns owing to the presence of high static charges [77].Okuzaki et al reported the observation of bundles vertically oriented from the solid collector towards the spinneret.They attributed this to the ionic conduction of poly(p-xylenetetrahydrothiophenium chloride)used in the experiment [89].6D o w n l o a d e d b y [U n i v e r s i t y D i S a s s a r i ] a t 07:47 03 F e b r u a r y 2016。

Electrospinning technology and application of electrospunnanofibers in different fieldsThe content of this article mainly refers to a review article by Professor Xia Younan [1]. I just reorganized his article content in my own language, and added some personal understanding on this basis . For the above reasons, I would like to express my special thanks to Mr. Xia Younan.1.Historical development of nanotechnology electrospinningElectrospinning technology, also referred to as electrospinning or electrospinning, can be traced back to 1 600. Will i am Gilbert observed a cone of water in the presence of an external electric field [2]. Then in 1887, Charles Boys Preparation of nanofibers by electrospinning using a viscoelastic liquid [1]. In 1938, electrospun nanofibers were used to make filter cores for air filtration devices, and electrospun nanofibers were first applied [1]. Since 1938, electrospinning technology continues to mature and develop, has now been applied in various fields, greatly promoted the progress and development of scientific research and industrial production [3, 4].2.Nano Electrospinning technology2.1.Electrospinning principlesFigure 1. Schematic diagram of an electrospinning device [ 5 ]Electrospinning technology refers to the process in which a polymer melt or solution forms fibers under the action of a high voltage electrostatic field. Electrospinning device mainly consists of three parts, namely, high voltage power supply, and receiving the spinneret plate (Fig. 1). The power source can be a DC power source or an AC power source. Different types of power sources have a certain influence on the formation of nanofibers, and will not be described in detail herein. Plastic pipe spinneret may be used, metal tubes and glass syringe with a needle or the like, the spinneret typically 0 .1 ~ 1 mm. The receiving plate is used for receiving a polymer formed by solvent evaporation or melt solidification, generally using a conductive metal plate, a silicon wafer, a conductive glass, and so on. In the specific use process, the surface of the metal plate should be wrapped with tin foil, woven fabric, etc., which facilitates the transfer of nano-spinning and prevents the receiving plate from being contaminated or soiled. [6]Power poles are respectively connected to the nozzle head and the receptacle, during the electrospinning, a polymer solution or melt brought to the surface charge and the force electric field is generated, a force opposite to the direction of the electric field of surface tension of the solution. As the voltage increases, the electric field force is greater than the surface tension, and the charged solution is ejected from the spinneret to form a jet stream. During the movement of the jet in the air, the process of solvent evaporation, cooling and cooling is gradually solidified, and finally collected on the receiver .Figure 2. Electrospun nanofibers schematic transverse forces suffered [ 7]When the solution is initially ejected from the spinneret, a linear motion is performed, but the surface tension and viscous force hinder its forward movement , and the acceleration gradually decreases, and at the same time, the fiber diameter becomes tapered. When the acceleration gradually decreases to 0 or a constant, any small disturbance will destroy any linear motion of the fiber. Due to the repulsion between the surface charge of the solution, an unstable perturbation segment region appears ,and the charge above the perturbation segment exerts a downward and outward repulsive force on it. F DO (Fig. 2) At the same time, the charge below the perturbation section exerts an upward and outward repulsive force F UO on it. The two forces produce a lateral resultant force F R that causes the nanofibers to bend [1, 7]. As the fiber gradually elongates, a second unstable bending phase occurs, followed by the third and fourth, until the nanofibers are cured, and the next level of bending no longer occurs. (Fig. 3).Figure 3. Schematic diagram of nanofiber bending motion [8]2.2.Materials used in electrospinning technologyElectrospinning technology can choose a large number of materials, but it is mainly divided into four categories, namely organic polymers, sol-gel materials, some small molecules and polymer and inorganic composite materials.anic polymerThe commonly used materials for electrospinning are organic polymers, which are mainly divided into two categories . One type is a polymer that can be dissolved in certain solvents to form a solution, which is currently the most widely used type because the operation process is relatively simple, the equipment requirements are relatively large, and the spun nanofibers are finer; It cannot be dissolved in the solvent, but it can be melted by heating . This requires a heating device around the needle , as shown in Figure 4 . By heating to melt the polymer, this method is often suitable for some of the materials with specific needs.Figure 4. Melt spinning a schematic view of apparatus [ 9]2.2.2.Sol-gel materialA colloid consisting of a dispersed phase ( suspended particles ) and a continuous phase ( suspension ) . When sufficient entanglement is formed inside the formed particles , the jet is a continuous structure and can also be used for electrospinning. [1] .2.2.3 small molecule solutionWhen the chain entanglement is large enough, the small molecule can also obtain the nanofiber directly by electrospinning. The key factor is to sufficiently strong interaction in the presence of a molecule between small molecules, such as self-assembled structure is formed in a highly concentrated solution or in the pure melt.positeThe application of composite materials is also very extensive, and some organic polymers are often combined with inorganic nanoparticles or nanowires to spin some functional nanofibers. For example, coating silica particles with polyvinyl alcohol (Fig. 5. Left ), polyvinylpyrrolidone coated silver nanowires (Fig. 5 . Right ) .Figure 5. Polyvinyl alcohol coated silica particles (left) [ 10] and polyvinylpyrrolidone coated silver nanowires( right ) electron micrograph [11]mon methods of operation for nanoelectrospinning technology2.3.1.Near-field and far-field patternThere are two main differences between the near field mode and the far field mode. One is the difference between the spinneret and the receiver, and the other is the difference in the power supply voltage. In far field mode, the distance from the spinneret to the receiver is 5 ~ 15 cm, the power supply voltage between approximately 1 0 ~ 20 KV [12]. When spinning in the far field mode, nanofibers that are finer than the near-field mode can be obtained, and the spinning speed is also faster. However, the position of the nanofibers on the receiving plate cannot be precisely controlled. In the near-field mode, the spinneret to the receiver distance of 5 00 um ~ 5 cm, between the power source voltage of approximately 0.6 ~ 3 KV. Using near-field mode while the spun nanofiber diameter with respect to the far field pattern is relatively large, it may be made to the precise control of the position of the nanofibers to obtain a variety of shapes and arrangement (Fig. 6) [13-15] .Figure 6. Various spinning patterns in near-field mode [16]2.3.2.Single and multi-needle spinneretsDue to the low spinning efficiency and small output of the single-needle spinneret, a multi-needle type spinneret has been developed, which has various types, multiple needles side by side, pyramid type and coaxial multi-needle, etc. Since there is a lateral electrostatic repulsion between the nanofibers, there is no adhesion between the fibers and the fibers. Among them, the coaxial multi-needle type spinneret can prepare nano-fibers with multi-layer structure, and can also prepare hollow nano-fibers with high flexibility and diversified products. Use multi-needle spinnerets can greatly improve production efficiency, reduce production costs, both for research or production aresignificant.2.3.3.Solid receiving plate and liquid receiving deviceFor receiver having non-uniform resolution conductive substrate (i.e., a metal and an insulator), they will produce distortion of an electric field toward the metal surface. Thus, the nanofibers will preferentially deposit on the surface of the metal region and extend into the insulating region, ultimately forming a patterned nanofiber mat. Nanofiber mats with different morphologies can be prepared by designing non-uniform receivers with different morphologies.In addition to receiving a solid plate, a liquid bath may be selected as a receiving apparatus. For some of the slower-removing nanofibers, the water bath can be used to accelerate the cooling and solidification speed and improve the dispersibility; for the case where the water evaporation in the nanofibers is too slow, it can be received by an ethanol bath, and the cellulose can be taken away by the ethanol. Moisture, speeds up curing.3."Smart" feature electrospinning nanofibersThrough electrostatic spinning techniques, can be obtained some special properties of nanofiber material, such as stress response, shape memory, self-cleaning, self-healing, "activity" and the like, respectively, do something briefly below.3.1.Stress responsivenessThere stress responsive polymer conformation and / or chemical changes in the external trigger stimulus, response time is inversely proportional to the speed of the stimulus. When the stimulating polymer is spun into nanofibers by electrospinning , the stress response speed is greatly enhanced . This improvement is mainly due to factors highly porous nanofiber mat structure and large specific surface area, small diameter and the like. Various types of stress-responsive nanofibers have been reported, such as cell sheets were harvested and controlled release applications.3.2.Shape memoryNanofibers have a shape memory effect at an external stimulus can be converted from a deformed state (temporary shape) to their original state (permanent shape). Having a shape memory effect nanofiber mat has been widely used in the field of tissue engineering and filtration. For example, nanofiber mats can control the growth of cells through shape changes , simulating changes in the dynamic environment of the human body. [17, 18].3.3.Self-cleaningAnd the like having a soft self-supporting electrical characteristic based on clean coating nanofibers. The chemical composition and surface wetting properties ofnanofibers can be well regulated. Coatings based on electrospun nanofibers are now used in various fields. For example, medical devices antifouling processing, production of protective clothing.3.4.Self healingSome engineering materials are often susceptible to cracks in the form of damage, so the development of self-healing materials to repair damage to restore its original performance is very important. One such method is to encapsulate the liquid healing agent in the sheath-sheath nanofibers and then embed the nanofibers into the material matrix. When a crack occurs, the healing agent will flow out and repair the broken nanofibers .3.5."Active"The so-called "active" nanofibers actually use a coaxial multi-needle type spinneret to encapsulate some bacteria, cells, viruses, etc. together with the culture solution in the sheath-sheath nanofibers. . These "active" nanofibersplay an important role in various biotechnology , such as microbial fuel cells, water decontamination membranes, and cell structure analysis .4.Application of nanofibers electrospunNanofibers prepared by electrospinning technology have been widely used due to their various excellent properties. Common application directions include: design and manufacture of air filtration devices, sewage purification treatment, recovery of heavy metal particles, and catalytic fields. Research on various types of batteries, light-emitting devices, biological applications, etc. In the future, electrospinning nanotechnology will play a greater role in promoting scientific research and the continuous development of human society.Electrospinning is a simple and versatile technique capable of producing nanofibers to suit various biomedical applications. By optimizing the parameters for electrospinning and/or combining with other methods, one can readily generate physical, biological, and chemical cues on electrospun nanofibers in a controllable and reproducible manner. Hence, prior to designing a nanofiber-based scaffold, it is necessary to take a full consideration of the typical cues needed, the properties of the nanofiber-based scaffold, and the specific requirements from different applications. At the current stage of development, the main challenge comes from the difficulty in directly generating nanofiber-based 3D scaffolds with diversified structures by electrospinning. In addition, a robust and flexible 3D scaffold is also needed in order tomimic the natural microenvironment of tumor ECM for cancer research. However, only a limited number of studies have been conducted with regard to the design and fabrication of nanofiber-based, 3D scaffolds, let alone the generation of topographic, physicochemical, and biological cues in the same scaffold. As such, there is an urgent need to find a simple and versatile strategy for tailoring the 3D architecture of a scaffold and thus optimizing the cell patterns.Electrospun nanofibers also allow for the versatile fabrication of cell−material composites. By integrating stem cells with a nanofiber-based scaffold and/or other cues (e.g., biochemical and electrical), one can further enhance the guidance provided by the scaffold and associated cues. As a result, it will be easier to provide a microenvironment similar to the native tissue, offering a desirable alternative for tissue regeneration. There is also a new trend in developing multifunctional scaffolds comprised of nanofibers and/or other bioactive components for localized tumor therapy and simultaneous tissue regeneration. To this end, the electrospun nanofibers are often integrated with topographic and biochemical cues during electrospinning, together with the functionalization of nano particles post electrospinning.It should be pointed out that past and current studies related to tissue regeneration are mostly conducted with healthy animals, which are not representative of actual clinical demands. For example, patients who require artificial vascular graft implantation are often accompanied by other comorbid ities, such as hyperlipidaemia, hypertension, and diabetes, which should also be considered when assessing the potential of vascular grafts that are intended for clinical applications.1000 To this end, developing appropriate animal models should also be taken into account when investigating tissue regeneration, as well as for cancer treatment and other related biomedical applications.5. Safety Concern of NanofibersAs a class of 1D nanomaterials, the safety concern of nanofibers originates not only from the production process but also from their potential harm to human beings and other living species. The safety concern during the production process is mainly related to the toxicity and environmental burden of the polymers and solvents as discussed above. Although electrospinning has been used to process recycled common plastics (e.g., PS, polyethylene terephthalate, polycarbonate, and their blends) into high-value and high performance products by eliminating the step of purifying the recycled raw materials, the use of organic solvents still makes this technology less environmentally benign. When assessing the impacts of electrospun nanofibers on human beings andother living species, the diameter, length, and composition of the nanofibers all need to be considered. It was reported that electr ospun Ag nanofibers of 5−20 μm in ,length were lodged in the lungs of mice and caused respiratory problems when they were intrapleurally injected into the lungs. Other studies also suggested the harmful effects of inorganic nanofibers that were relatively short, with diameters in the range of tens of nanometers or below. Such short nanofibers may be easily inhaled to cause inflammatory reactions in lungs. To this end, we should take lesson from the case of asbestos, a class of natural nanofibers that were very popular for use as building materials but later found to be carcinogenic. In general, electrospun nanofibers have a length more than a few centimeters. At such a length scale, the chance for electrospun nanofibers to reach the lung is quite small. As shown in a study involving rat silicosis model, biodegradable and biocompatible electrospun cellulose nano-fibers (20 μm in length) inhaled into the lung could even facilitate the clearance of silica particles. Nevertheless, only a very limited number of studies have been conducted so far in addressing the inhalation safety of electrospun nanofibers; no conclusion can be drawn yet6.References[1] Jiajia Xue, Tong Wu, Yunqian Dai, Younan Xia. Electrospinning and Electrospun Nanofibers: Methods, Materials, And Applications . Chem. Rev. 2019 119 5298−5415 .[2] Gilbert, W. De Magnete; Courier: New York, 1958 .[ 3 ] Li, D.; Wang, Y.; Xia, Y. E lectrospinning of Polymeric and Ceramic Nanofibers as Uniaxially Alig ned Arrays. Nano Lett. 2003, 3, 1167−1171.[4] Theron, A.; Zussman, E.; Yarin, A. Electrostatic Field−Assisted Alignment of Electrospun Nanofibres . Nanotechnology 2001, 12, 384− 390.[ 5 ] Xue, J.; Xie, J.; Liu, W.; Xia, Y. Electrospun Nanofibers: New Concepts, Materials, and Applicat ions. Acc. Chem. Res. 2017, 50, 1976−1987.[ 6 ] Wang Ce, Lu Xiaofeng et al; organic nano-functional materials - high-voltage electrospinning technology and nanofibers; Science Press; 2 011.[ 7] Reneker, DH; Yarin, AL Electrospinning Jets and Polymer Nanofibers. Polymer 2008, 49, 2387−2425.[8] Reneker, DH, Fong, H., Eds. Polymeric Nanofibers; American Chemical Society: Washington, DC, USA, 2006; DOI: 10.1021/bk-2006-0918.[9] Brown, TD; Dalto n, PD; Hutmacher, DW Melt Electrospinning Today: An Opportune Time for an Emerging Polymer Process. Prog. Polym. Sci. 2016, 56, 116−166.[10] ) Jin, Y.; Yang, D.; Kang, D.; Jiang, X. Fabrication of NecklaceLike Structures via Electrospinning. Langmuir 2010, 26, 1186−1190.[11] Zhang, CL; Lv, KP; Hu, NY; Yu, L.; Ren, XF; Liu, SL; Yu, SH Macroscopic-Scale Alignment nt of Ultralong Ag Nanowires in Polymer Nanofiber Mat and T heir Hierarchical Structures by Magnetic-Field-Assisted Electrospinning. Small 2012, 8, 2936−2940.[12] Huang, Y.; Bu, N.; Duan, Y.; Pan, Y.; Liu, H.; Yin, Z.; Xiong, Y. Electrohydrodynamic Direct-Wri ting. Nanoscale 2013, 5, 12007− 12017.[13] Fuh, YK; Hsu, HS Fabrication of Monolithi c Polymer Nanofluidic Channels via Near- Field Electrospun Nanofibers as Sacrificial Templates. J. Micro/ Nanolithogr., MEMS, MOEMS 2011, 10, 043004.[14] Wang, X.; Zheng, G.; Xu, L. ; Cheng, W.; Xu, B.; Huang, Y.; Sun, D. Fabrication of Nanochannels via Nea r−Field Electrospinning. Appl. Phys. A: Mater. Sci. Process. 2012, 108, 825−828.[15] Chang, J.; Liu, YM; Heo, K.; Lee, BY; Lee, SW; Lin, L. W. Direct−Write Complementary Gr aphene Field Effect Transistors and Junctions via Near−Field Electrospinn ing. Small 2014, 10, 1920− 1925.[16] Zheng, G.; Li, W.; Wan g, X.; Wu, D.; Sun, D.; Lin, L. Precision Deposition of a Nanofibre by Near−Field Electrospinning. J. Phys. D: Appl. Phys. 2010, 43, 415501.[17] Tseng, LF; Mather, PT; Henderson, JH Shape-MemoryA ctuated Change in Scaffold Fi ber Alignment Directs Stem Cell Morphology. Acta Biomater. 2013, 9, 8790−8801.[18] Wang, J.; Quach, A.; Brasch, M. E.; Turner, CE; Henderson, JH On-Command on/off Switchin g of Progenitor Cell and Cancer Cell Polarized Motility and Aligned Morphology via a Cytocompatible Shape Memory Polymer Scaffol d. Biomaterials 2017, 140, 150− 161.。

聚合物纳米线的研究进展唐知灯（湖南工程学院化学化工学院—湖南湘潭411100）摘要：全面综述了聚合物纳米线的制备方法及研究现状，根据聚合物纳米线的制备机理和实施方法的不同，可以分为静电纺丝法, 模板法，自主装法三种。

本文评述了其研究现状及可能的应用前景。

关键词：纳米线；聚合物纳米线；研究进展。

Advanced in polymer NanowireTangzhideng（Department of Chemistry and Technology, Hunan Institute of Engineering, HunanXiangtan 411100)Abstract：An overview of the latest research metal.It can be distributed electrospinning ,porous template and self-assembly by its diffirent synthesis.The possible applications of such kind of materials in the future were foreeasted．Key words：nanowire polymer Nanowire advanced引言：聚合物纳米线作为一种特殊结构的纳米材料有其特别的性能和用途。

纳米线作为一维纳米材料，是指直径处于10nm～100nm的纳米尺度而长度可迭微米量级的线性纳米材料。

本文将着重评述聚合物纳米线的制备方法及机理、性能以及潜在的应用等。

1 聚合物纳米管的制备方法及原理聚合物纳米线自发现几年来,研究一直在不断深入、完善和创新中。

其主要着眼点在于通过新的制备方法,新的聚合物品种等来开发新的聚合物纳米管,以期寻找新的性能及用途。

综合起来,目前已有的制备方法可分为多孔模板法、线模板法、自组装法等几大类。

现根据目前研究情况,从制备方法及原理的角度归纳如下表,并分述如下:1．1．1静电坊丝法：静电纺丝法是将聚合物溶液或熔体置于几千至上万伏高压电场，带电的聚合物液滴在电场力作用下在毛细管的Taylor锥顶点被加速，克服表面张力形成喷射细流，细流在喷射过程中溶剂蒸发固化，最终落在接收装置上，形成类似非织布状的纤维毡(Fig．I)t”。

Journal of Chromatography A,1278 (2013) 1–7Contents lists available at SciVerse ScienceDirectJournal of ChromatographyAj o u r n a l h o m e p a g e :w w w.e l s e v i e r.c o m /l o c a t e /c h r o maA single step technique for preparation of porous solid phase microextraction fibers by electrochemically co-deposited silica based sol–gel/Cu nanocompositeMohammad Saber Tehrani a ,∗,Parviz Aberoomand Azar a ,Sirwan Mohammadiazar ba Department of Chemistry,Science and Research Branch,Islamic Azad University,P.O.Box 14515-775,Tehran,Iran bYoung Researchers and Elites Club,Science and Research Branch,Islamic Azad University,Tehran,Irana r t i c l ei n f oArticle history:Received 22May 2012Received in revised form 1November 2012Accepted 12November 2012Available online 21 November 2012Keywords:Sol–gelElectrochemical co-deposition Nanocomposite Coppera b s t r a c tIn this study,electrochemically co-deposited 3-trimethoxysilyl propyl methacrylate (3TMSPMA)/Cu nanocomposite is introduced as a novel and single-step technique for preparation of efficient and unbreakable solid phase microextraction (SPME)fibers;having strong interaction between the substrate and the coating.The applicability of prepared nanocomposite films was evaluated through extraction of some aromatic pollutants as model compounds from the headspace of aqueous samples in combination with gas chromatography–mass spectrometry (GC–MS).Different parameters affecting the structure and composition of the deposited films including applied potential,electrodeposition time,and precursor con-centration;and the parameters affecting extraction efficiency such as extraction temperature,extraction time,and salt content were investigated.The results showed that morphology and grain size of the films are strongly affected by the ratio between the sol–gel precursor and Cu 2+ions.Furthermore,potential of deposition influences the composition of films as it controls the kinetics of sol–gel/Cu co-deposition.Finally,characterization of the deposited films was accomplished by scanning electron microscopy (SEM)and thermogravimetric analysis (TGA).© 2013 Published by Elsevier B.V.1.IntroductionSolid-phase microextraction (SPME),developed by Belardi and Pawliszyn [1,2],is a fast,simple,economical,and efficient solvent-free method for extraction and pre-concentration of analytes from various sample matrices [3,4].This technique is based on distribu-tion of the analytes between the sample (or its headspace)and the stationary phase coated on a solid support (fiber).Notwithstand-ing various advantages of SPME,commercial SPME fibers encounter some drawbacks [5],which include low thermal stability,fragility,and high cost.In this regard,some coating techniques have been proposed to overcome these drawbacks and enhance the performance of SPME fibers.These coating techniques include physical deposition [6,7],electrochemical deposition of conducting polymers [8–10],pasting with adhesives [11],and sol–gel technology [12–18].One of the most frequently applied techniques for preparation of SPME fibers is sol–gel dip-coating methodology.Briefly,in this method the surface of fused silica (or recently metal alloy)fiber is hydrolyzed by NaOH,and then neutralizd by HCl to create OH∗Corresponding author.Tel.:+982144869761;fax:+982144869761.E-mail addresses:drmsabertehrani@yahoo.om (M.Saber Tehrani),pabroomand@ (P.Aberoomand Azar),mohammadiazar@iausdj.ac.ir (S.Mohammadiazar).functional groups at the fiber surface.In the following,to coat the modified fiber by sol–gel sorbent,it is inserted in a coating media that usually include a mixture of alkoxysilane precursors,small amounts of water,and an acid catalyst [19,20](more often trifluoroacetic acid,TFA),or a base catalyst for a period of time (20–40min)[21].Irradiation can also catalyze the sol–gel process [22–24].Due to fragility of the silica rods,which were traditionally used as substrate,recently metal fibers such as platinum wire [9,25],anodized aluminum wire [13],gold wire [26],titanium wire [27],stainless steel [3,28],Cu wire [29]and Ni–Ti coated with ZrO 2[16]have been introduced.In all these fibers,some pretreatments are needed prior to sol–gel deposition,to create active sites on substrate to provide interaction between stationary phase and substrate.It is believed that the reasons for some disadvantages of commercially available SPME fibers are lack of proper chemical bonding of stationary phase coating with the fiber surface and the relatively high thickness of conventional fibers [30].In this study,electrochemical co-deposition of silica sol–gel/Cu nanocomposite on Cu wire is proposed as a novel and single-step technique (without fiber pretreatment step)for preparation of thin SPME fibers with strong interaction between coating and substrate.Moreover,the technique does not need the catalyst (acid,base,or irradiation)for preparation of unbreakable and porouse SPME fibers.0021-9673/$–see front matter © 2013 Published by Elsevier B.V./10.1016/j.chroma.2012.11.0352M.Saber Tehrani et al./J.Chromatogr.A1278 (2013) 1–72.Materials and methods2.1.InstrumentationElectrochemical experiments were performed with an AutoLab potentiostat(PGSTAT101,EcoChemie,Utrecht,The Netherlands) using a standard three-electrode cell with Ag/AgCl as a reference electrode and a Pt electrode as a counter electrode and Cu wire(OD:∼198␮m)as the working electrode.A Hewlett-Packard(HP,Palo Alto,USA)HP6890plus series GC equipped with a split/splitless injector and a HP5973mass-selective detector system were used.The MS was operated in the EI mode(70eV).Helium(99.999%)was employed as the car-rier gas and itsflow rate was adjusted to1mL min−1.Separation of polycyclic aromatic hydrocarbons(PAHs)was performed on a 60m×0.25mm HP-5MS column(0.25-mmfilm thickness).The column was held at a temperature of50◦C for3.5min,increased to180◦C at a rate of15◦C min−1and kept constant for7min and then raised to260◦C at20◦C min−1and kept at this temperature for 5min.The GC–MS interface,ion source,and quadrupole tempera-tures were set at280,230,and150◦C,respectively.The injector temperature was set at250◦C andfiber desorption was carried out in the splitless mode for3min.The detection method was pro-grammed in SIM mode(Table1).SEM images were acquired by an S-4160FE-SEM instru-ment from Hitachi Science Systems(Hitachinaka,Japan),with an electron-beam intensity of15keV,unless otherwise written.A TG 209F1Iris-Thermogravimetric Analyzer from NETZSCH(Germany) was employed to investigate thermal stability of the preparedfiber.2.2.ChemicalsTetraethoxyorthosilicate(TEOS),3-trimethoxysilyl propyl methacrylate(3TMSPMA),and3-trimethoxysilyl propyl amine (3TMSPA)were purchased from Aldrich(98%purity)and used as-received.Absolute ethanol(A.R.,Frutarom),extra-pure KNO3 (Merck),CuCl2(Aldrich),potassium hydrogen phthalate and HCl (Merck),and deionized water(Easy Pure UV,Barnstead)were used for preparing the different solutions.Naphthalene(NAP),acenaphthene(ACE),acenaphthylene (ACY),fluorene(FLU)were purchased from Merck and their standard solutions were prepared at a concentration of1000mg L−1 in methylene chloride.Working standards of PAHs were prepared every week at a con-centration of10mg L−1by diluting with methanol.The stock and working standards were stored at4◦C in the refrigerator.The aque-ous solutions were prepared daily by diluting standard solution with distilled water to give the corresponding solution for extrac-tion.All solvents used in this study were of HPLC-reagent grade.2.3.Preparation of SPMEfibersDetails of this procedure are reported elsewhere[31]with some modification;briefly,the working electrode,i.e.,Cu wire was washed prior tofilm deposition with water,ethanol,and water again,followed by drying at the room temperature for2h.The solu-tion for electrodeposition of silica-based sol–gelfilms consisted of 400␮L of sol–gel precursor(TEOS,3TMSPMA or3TMSPA),5mL of0.2M KNO3,and phthalate buffer(1mM,pH=3.5).Hydrolysis was carried out by stirring the above-described solution for2h at the room temperature.Cupric ions(0.5–20mM)were added to the solution at this stage.Then,the electrodes were placed in the elec-trochemical cell and a constant negative potential(between−0.5 and−1.3V vs Ag/AgCl)was applied to the electrode for5–20min under continuous stirring.The current as a function of time was recorded.After this period,the electrode was slowly withdrawn while the potential was still applied.The electrode was dried in air for24h before carrying out further characterization and usage. 2.4.SPME procedureThe SPME device for manual extraction consists of a homemade holder assembly and several replaceable home-madefiber assem-blies.Performance of the new SPMEfiber was evaluated through extraction of some PAH compounds from aqueous samples. Headspace sampling,magnetic stirring,and6mL of aqueous sam-ple in a10-mL vial were used.Parameters that influence PAHs microextraction procedure including extraction time(5–30min), extraction temperature(10–50◦C),and salt content(0–30%w/v, NaCl)were studied.3.Results and discussionThefirst study where sol–gel was electrochemically deposited on metal surfaces was reported by Shacham et al.[32],who pro-posed a new approach for sol–gelfilm formation.They applied this technique in the anti-corrosion treatment of metal surfaces.The method involved electrochemical change of the pH value near a metal surface by solvent reduction or oxidation.Fur-thermore,the approach was based on the“two-step”sol–gel preparation procedure,in which hydrolysis of a metal alkoxide is carried out initially at a low pH value,followed by polycon-densation of the hydrolyzed precursor at a higher pH.According to this method,applying negative potential to metal substrate increases the pH value at the electrode surface,which catalyzes the polymerization of sol–gel monomers,leading to deposition of the appropriate oxidefilm.Silicatefilms can be electrode-posited on any conducting surface,but the sol–gelfilmflakes off after drying,because of weak interaction between substrate and coating.Toledano et al.[31]expanded electrochemical deposition approach to depositing sol–gel/metal nanocomposites by simulta-neous reduction of metal ions,e.g.,Cu2+,and the solvent(water), resulting in co-deposition of metal and sol–gel nanocomposite.This approach can solve the problem of lack of adherence of the SPME coatings to the substrate;because the metal ions and sol–gelfilm are co-deposited at the same time.The Cu2+ions were selected as metal ions,which have good adherence to the metal substrate (including Cu)surfaces.3.1.Study of thefiber preparation parameters3.1.1.Selection of the coating typeTo select the best coating,fourfibers with different polarities were constructed in similar conditions with the exception of pre-cursor type(Table2).They were conditioned and exposed to the headspace of aqueous samples containing target PAHs.As it can be seen in Fig.1,the nanocompositefiber prepared by3TMSPMA precursor shows higher extraction efficiency than others.Then,thisfiber was used for other works in continue.The3TMSPMA sol–gel precursor,which served as a bifunctional reagent,contains both methacrylate and alkoxysilane groups (Table2).It can extract aromatic hydrocarbons through␲–␲inter-action,while other precursors do not have␲bonds to interact with aromatic rings.3.1.2.Influence of electrochemical parametersChronoamperometry technique was selected to deposit nanocomposite on the Cu wire,and when negative potential is applied to the cathode inserted in a solution containing electrolyteM.Saber Tehrani et al./J.Chromatogr.A 1278 (2013) 1–73Table 1Retention time,selected ions and statistical parameters.CompoundStart time for SIM (min)Retention time (min)Selected ions (m /z )LOD (ng mL −1)Linear range (ng mL −1)Regression equationr 2RSD (%)Single fiber n =5Fiber-to-fiber n =4Nap. 5.012.61280.010.1–10y =8729x +44850.991876Ace.14.017.3152,1530.020.1–10y =6187x +57290.98811012Acy.17.718.2153,1540.020.1–10y =14267x +81350.99761417Flu.19.020.7165,1660.010.1–10y =8628x +61580.9948611Table 2Precursor types and their structure.NameAcronymStructureTetraethoxysilaneTEOSSiOCH OCH CH O 333OCH 33-Trimethoxysilyl propyl methacrylate3TMSPMASi CH 2CH 2CH 2OCOC CH 2CH 3OCH OCH CH O 3333-Trimethoxysilyl propyl amine3TMSPASiOCH CH OCH 2CH CH 22333NH 2and Cu 2+ions,at least two reactions can occur simultaneously.Firstly,Cu 2+ions are reduced to metal Cu (Eq.(1)).Cu 2++2¯e →Cu (s)(1)Secondly,OH −ions and H 2bubbles are produced from water(and maybe O 2)reduction on the cathode surface via a number of electrochemical processes.The most probable reactions at the electrode surface are (Eqs.(2)–(4))[34,35]:2H 2O +2¯e →2OH −+H 2(g)(2)O 2+2H 2O +4¯e →4OH −(3)parison of extraction efficiency of prepared nanocomposite fibers bydifferent precursors (the Cu 2+concentration was 10mM in all of them),PAH con-centration:100ng mL −1,extraction temperature:25◦C,extraction time:20min,no salt addition,MS in scan mode.O 2+2H 2O +2¯e →H 2O 2+2OH −(4)More precisely,the strict control in terms of potential and dura-tion of potential application allowed obtaining a desired thickness and porosity coating deposition.All the above reactions have very large overpotentials,and all are dependent on the electrode material.Therefore,it is difficult to precisely determine which reaction is occurring conclusively [36].Fig.2schematically depicts the reactions involved in silica sol–gel/Cu nanocomposite preparation.The OH −ions act as the cat-alyst for preparation of thin film of sol–gel;hence a base-catalyzed sol–gel process occurs at the electrode surface,which causes imme-diate condensation of the silane on electrode surface.Porosity of the film highly depends on the manner in which it is formed,the structure of the sol,and the evaporation and drying rates [37,38].One unique aspect of electrodeposited sol–gel proce-dure is that gelation occurs separately from evaporation and drying,potentially leading to formation of films with higher porosity [36].Also,evolution of H 2bubbles through film preparation increases the film porosity.As it can be seen in Fig.3A,the applied potential strongly affects the morphology and efficiency of the fibers.At more negative potentials,the average size of grains decreased and their density increased [32].The effect of potential on density of the electrode-posited films can be interpreted on the basis of a nucleation and growth mechanism [39].A more negative potential facilitates the formation of nucleation sites and therefore reduces the size of aver-age nuclei (higher porosity).As mentioned above,at more negative potentials in addition to the reduction of Cu 2+ions,water and/or O 2molecules reduce to OH −and H 2bubbles.At higher potentials intensive evolution of H 2gas,which attacks the electrode surface,leads to non-uniformity4M.Saber Tehrani et al./J.Chromatogr.A 1278 (2013) 1–7Fig. 2.Schematic representation of electrochemical co-deposition of silica sol–gel/Cu nanocomposite.and higher porosity of the nanocomposite film.As seen in Fig.3A,potentials larger than −1100mV reduce the extraction efficiency of the fiber;thereby deteriorating the film through intensive evo-lution of H 2gas.Thus,potential of −1100mV was selected as optimum voltage for preparation of SPME fibers.As it can be seen in Fig.3B,extraction efficiency increases with increasing the time duration until 10min,owing to the increase in fiber thickness with time.However,it will be constant at longer time durations,probably because of the low conductivity of the nanocomposite at higher thicknesses and the slow growth of the film.Therefore,10min was selected as the optimal time duration of potential application.3.1.3.Influence of solution compositionDifferent volumes of 3TMSPMA were added to the sol solu-tion,while the concentration of Cu 2+ions was held constant at 10mM.Extraction efficiency increases at higher precursor vol-umes,because of the higher percentage of the sol–gel at sol–gel/Cu nanocomposite (Fig.3C).According to the results,400␮L was con-sidered as the optimal 3TMSPMA volume.Concentration of the Cu 2+ions in the deposition solution is another factor,which affects the morphology and composition and subsequently efficiency of the SPME fibers.This in turn affects the mechanical strength of the fiber.The results showed that as the concentration of Cu ions increases,the extraction efficiency decreases.This is caused by the increase in the percentage of Cu in the film and the increase in the average grain size (lower porosity)and decrease in the percent-age of sol–gel.It should be mentioned that the extraction phase is sol–gel phase;not the Cu phase.The concentration of 1mM of Cu 2+was selected as the optimal concentration for Cu 2+ions,as at this concentration the mechanical strength of the fiber is high without any reduction in extraction efficiency of the fiber.At concentra-tions lower than 1mM of Cu 2+,adherence of the sol–gel film to the substrate is weak.3.2.Study of extraction parametersDetermination of some ultra-trace pollutants in water is chal-lenging due to the low sensitivity of some of the existing SPME coatings.Increasing the coating thickness is an effective wayofFig. 3.Effect of preparation parameters on extraction efficiency of prepared nanocomposite,(A)applied potential in the presence of 10mM CuCl 2,200␮L 3TMSPMA,time duration of potential application:10min,other conditions were as described in Fig.1,with the exceptions that MS was in SIM mode,(B)time dura-tion of electrodeposition,applied potential was 1100mV,and (C)precursor volume,applied potential:1100mV,time duration of potential application:10min.enhancing surface area and sample capacity.In addition,preparing a porous coating is another method to enhance extraction efficiency [33].Prepared nanocomposite fiber was used to extract some PAH pollutants and their extraction parameters were optimized.SPME is an equilibrium technique and equilibrium is affected by various factors such as extraction time,extraction temperature,and ionic strength.The optimal experimental conditions should be investi-gated for each compound and for the selected fiber.M.Saber Tehrani et al./J.Chromatogr.A1278 (2013) 1–75Fig.4.Optimization of parameters affecting PAHs extraction at100ng mL−1concen-trations,conditions were as described in Fig.3C,(A)extraction time,(B)extraction temperature,extraction time:20min,and(C)ionic strength,extraction time: 20min,extraction temperature:30◦C.Influence of the extraction time(10–50min)for each compound using the3TMSPMA/Cu nanocompositefiber was evaluated.The study was performed for100ng mL−1PAHs under agitated samp-ling conditions in the10mL and4mL headspace(HS).Fig.4A shows the extraction time profile of the nanocompositefiber.As it can be seen in Fig.4A,after15min the increase in peak areas slightly changed for most of the compounds,reaching the highest extraction between15and20min.The porous structure helps faster mass transfer during extraction;so the equilibration time is relativelyshort.Fig.5.Micrographs of Cu wire(A)before,(B and C)after coating with nanocomposite film at different magnifications.Fig.4B represents the extraction temperature profiles for the PAHs in aqueous media.It is shown that extraction ability of the fiber increased with temperature at30◦C,but decreased signif-icantly at temperatures higher and lower than30◦C.Extraction ability is mainly controlled by two factors;distribution velocity and partition coefficient.The distribution velocity,which helps analytes to move near the solid-phase coating,increases with increasing6M.Saber Tehrani et al./J.Chromatogr.A1278 (2013) 1–7Table3Comparison of limit of detection(ng mL−1)of proposedfiber with commercial SPMEfibers.Ref.Kind offiber Naphthalene Acenaphthylene Acenaphthene Fluorene Current method3TMSPMA/Cu nanocomposite0.010.020.020.01[41]Polyacrylate(85␮m thickness)9.27.58.19.3[42]PDMS(7␮m thickness)7.8109.89.3[41]DVB/PDMS a(65␮m thickness)17.458.910.68.2a Divinylbenzene/Polydimethylsiloxane.the temperature.Moreover,extraction is an exothermic process and the partition coefficient,which determines the ratio of ana-lytes extracted,is inversely related to temperature.Thefirst factor is dominant in the temperature range less than30◦C,while the second becomes dominant at temperatures higher than30◦C.Desorption temperature for all extractions was set to250◦C. After desorption at elevated temperatures,some of the sorbed ana-lytes may be still retained by the coating,especially using the thick coatedfibers.Thus,an additional wash step is required to pre-vent carry-over,or a longer desorption time should be applied. Carry-over is the major limiting factor for PAH analysis by SPME, especially for the four-ring systems and higher.The possible carry-over of analytes was studied for prepared nanocompositefiber,and results showed that after4min desorption at250◦C,the amount of retained analytes is negligible.Relatively short sorption and desorption times are due to the porous structure of preparedfiber and higher mass transfer rate from and to thefiber.Influence of sodium chloride concentration on the extraction process was also studied(Fig.4C).Peak areas of all PAHs were increased with the increase in salt concentration,due to“salting out effect”and attaining maxima when NaCl concentration reaches25% (w/v).As seen in Fig.4C,at concentrations higher than25%(w/v), the viscosity increase affects extraction efficiency,and then peak areas are decreased.Diffusion coefficient depends on the size and shape of molecules,interaction with the solvent,and viscosity of the solvent.The relationship between diffusion coefficient(D)and viscosity(Á)can be expressed via the following equation:D=16 ÁrkTwhere k is the Boltzmann constant,T is absolute temperature,and r is radius of the molecule[40].At higher solution viscosities,the diffusion coefficient will be low,and consequently the mass trans-fer rate(rate of analyte release)in solution and from solution to headspace,may be slow and the extraction process may be kineti-cally limited(need more time to equilibrate).Based on the method optimization,an extraction temperature of30◦C,extraction time of15min,salt concentration of25%(w/v), maximum rate of stirrer,desorption temperature of240◦C,and desorption time of4min were selected for determination of PAHs in water.Double distilled water spiked with selected PAHs was used to evaluate the precision of measurements,limit of detections,and dynamic range of the method(Table1).The repeatability and repro-ducibility of preparedfibers for PAH analytes were in the range of 6–14%,and6–17%,respectively.Table3shows the comparison of limit of detections obtained from the present work with other relevant reports.Clearly,the nanocomposite coating(∼9␮mfilm thickness)fiber developed exhibits higher analytical performance in comparison to those achieved by commercialfibers.3.3.Fiber characterizationCharacterization of the novelfiber was performed through scan-ning electronic microscopy(SEM),and thermogravimetry analysis (TGA).Fig.5A and B represents micrograph of the Cu wire,before and after electrodeposited by nanocomposite,respectively.Fig.5C shows SEM image of nanocomposite at higher magnification.As it can be seen from the graphs,the sol–gel coating possesses a porous structure.A high surface area will be able to provide large stationary phase loading and therefore,high extraction capac-ity.Thermal stability of the preparedfiber was investigated by TGA.The thermogram shows rather good consistency and ther-mal stability in the temperature range of30up to400◦C (Fig.6).High stability of thefiber is due to the inherent high thermal stability of the sol–gel-based materials and covalent bonds between3TMSPMA/Cu nanocomposite and the metal sur-face.The reusability offibers was studied at desorption temperature of250◦C and4min desorption time for each analysis.Theresults Fig.6.TGA and DTG curves of the3TMSPMA/Cu nanocomposite coating under nitrogen at a heating rate of10◦C min−1.M.Saber Tehrani et al./J.Chromatogr.A1278 (2013) 1–77showed that onefiber can be used up to70times without any decrease in extraction efficiency.4.ConclusionsElectrochemically co-deposited3TMSPMA/Cu nanocomposite film using chronoamperometry technique was proposed as a novel and single step approach,without modification of substrate sur-face step.The prepared SPMEfibers are porous,unbreakable;also, strong interaction between the substrate and coating is created through the nanocomposite formation.The results showed that applied potential and time duration of potential application,as well as solution composition had strong effects on efficiency of the preparedfibers.Parameters affecting extraction efficiency of thefiber through extraction of some PAHs were optimized.The results showed that extraction time is relatively short because of porous structure and subsequently fast mass transfer of analytes. 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PMMA系聚合物在锂离子电池凝胶电解质领域中的研究进展焦晓宁;周锦涛;陈洪立【摘要】The characteristics and application of polymethyl methacrylate (PMMA) used for lithium-ion batteries gel polymer electrolyte (GPE) are summarized. One of the advantages of PMMA-based GPE is the good interface stability with lithium metal electrode, and it also has high ionic conductivity of 10-3 S/cm at room temperature, and its cycle performance is better than that of some other gel electrolyte. But the weakness of mechanical strength limits its application. But the weakness of mechanial strength limits its application. The mechanial property of PMMA-based GPE can be improved by combining with other polymers, inorganic nanoparticles, polyolefin films, even nanworens to form gel electrolytes through blending, coating, copolymerization, etc. The trend of research on PMMA-based GPE is to prepare multi -layered composite porous electrolytes by electrospinning.%综述了聚甲基丙烯酸甲酯（PMMA）作为锂离子电池凝胶电解质的特性及应用情况。

收稿日期：2022-04-17基金项目：国家自然科学基金资助项目（21476172）通信作者：张庆印（1977—），男，博士，副教授，主要研究方向为锂/钠离子电池电极材料的合成与模拟。

E-mail:*************************.cn钠离子电池用石墨烯掺杂多孔材料的电化学性能张庆印，刘小露（天津工业大学化学工程与技术学院，天津300387）摘要：为了增加硬碳电极材料的导电性，选取石墨烯作为添加剂，采用涂覆法制备了石墨烯掺杂多孔材料，通过SEM 、XRD 、BET 、蓝电电池测试系统和电化学工作站等对所得石墨烯多孔材料的结构和电化学性能进行表征和测试，探究不同碳化温度对于石墨烯掺杂多孔材料电化学性能的影响。

结果表明：石墨烯掺杂多孔材料显示出均匀、丰富的孔结构和增强的石墨化程度，可降低接触电阻，缩短扩散距离，增强电子的传导性，用作电池负极时可有效提高钠离子电池的可逆比容量、倍率和循环性能；当碳化温度为1100益时，所制备的石墨烯掺杂多孔材料电极表现出363.8mA ·h/g 的高可逆比容量，在100mA/g 的电流密度下，循环300圈后，其可逆比容量基本无损失，表明该石墨烯掺杂多孔材料具有优异的电化学性能。

关键词：钠离子电池；硬碳；石墨烯；多孔材料；电化学性能中图分类号：TQ152文献标志码：A 文章编号：员远苑员原园圆源载（圆园23）园5原园园36原07Electrochemical properties of porous materials doped with graphene forsodium ion batteryZHANG Qingyin ，LIU Xiaolu（School of Chemical Engineering and Technology ，Tiangong University ，Tianjin 300387，China ）Abstract ：In order to increase the conductivity of the anode material for hard carbon袁the graphene was selected as an addi鄄tive袁the graphene -doped porous material was produced by coating method.The prepared graphene -doped porous material was characterized by SEM袁XRD and BET袁and the electrochemical property was tested using electrochemical workstations and blue battery test systems.The effects of different carbonization temperature on electrochemical properties of the graphene -doped porous material were explored.The results show that the graphene-doped porous material has uniform and rich pore structure and enhanced graphitization degree袁which can reduce contact resistance袁shorten diffusion distance袁and enhance electronic conductivity.When used as the battery cathode袁they can effectively improve the reversible specific capacity袁magnification and cycling perfor鄄mance of sodiumion battery.When the carbonization temperature is 1100益袁the prepared graphene -doped porous material electrode exhibites a high reversible specific capacity of 363.8mA 窑h/g.After 300cycles at cur鄄rent density of 100mA/g袁its reversible specific capacity has almost no loss袁which indicating that the graphene-doped porous material electrode has excellent electrochemical properties.Key words ：sodium ion battery曰hard carbon;graphene曰porous materials曰electrochemical property进入21世纪，消耗化石燃料造成的能源短缺和环境污染问题引起了人们的广泛关注，储能已经成为全球关注的焦点。

第29卷 第4期2008年4月纺 织 学 报Journal of Textile Research Vol.29 No.4Apr. 2008文章编号:0253 9721(2008)04 0001 04溶液性质对静电纺纤维形态的影响李 妮,覃小红,王善元(东华大学纺织学院,上海 201620)摘 要 以聚乙烯醇和聚丙烯腈溶液为原料进行静电纺丝,采用扫描电镜观察纳米级纤维的形态。

在影响静电纺纳米级纤维的众多参数中,分析了溶液质量分数及其导电性对串珠和纤维直径的影响。

研究发现随着溶液质量分数的增加,串珠明显减少,纤维直径增加,并得出溶液质量分数是影响串珠和纤维直径大小的主要因素;通过添加不同质量分数的盐,改善溶液的导电性,研究发现随着溶液导电性的增加,纤维直径离散度明显减少,从而得出溶液导电性是影响纤维直径离散度的主要因素。

关键词 静电纺;纳米级纤维;导电性;直径;串珠中图分类号:TS 102 文献标识码:AEffect of solution properties on the morphology of electrospun nanofibersLI Ni,QIN Xiaohong,WANG Shanyuan(College o f T e xtiles ,Donghua Unive rsity ,Shanghai 201620,China )Abstract Electrospinning method was used to fabricate P VA and PAN nanofibers.The effect of solution massconcentration and conductivity on electrospun fiber morphology was investigated by scanning electron microscopy(SEM).The result showed that the beads decreased and fiber diameter increased with increasing solution mass concentration which was found to have considerable effec t on bead free nanofibers and fiber diameter.Solution conductivity was improved by adding different LiCl mass concentrations into electrospinning solution.With increasing solution conduc tivity,fiber s discrete coefficient decreased remarkably.Thus it is concluded that solution conductivity is the primary factor influencing the discrete coefficient of the fiber.Key words electrospinning;nanofiber;conduc tivity;diameter;beaded fiber 收稿日期:2007-05-31 修回日期:2007-08-07基金项目:国家自然科学基金资助项目(10602014)作者简介:李妮(1979 ),女,博士生。

光学专业英语部分refraction [rɪˈfrækʃn]n.衍射reflection [rɪˈflekʃn]n.反射monolayer['mɒnəleɪə]n.单层adj.单层的ellipsoid[ɪ'lɪpsɒɪd]n.椭圆体anisotropic[,ænaɪsə(ʊ)'trɒpɪk]adj.非均质的opaque[ə(ʊ)'peɪk]adj.不透明的；不传热的；迟钝的asymmetric[,æsɪ'metrɪk]adj.不对称的；非对称的intrinsic[ɪn'trɪnsɪk]adj.本质的，固有的homogeneous[,hɒmə(ʊ)'dʒiːnɪəs;-'dʒen-] adj.均匀的；齐次的；同种的；同类的，同质的incidentlight入射光permittivity[,pɜːmɪ'tɪvɪtɪ]n.电容率symmetric[sɪ'metrɪk]adj.对称的；匀称的emergentlight出射光；应急灯.ultrafast[,ʌltrə'fɑ:st,-'fæst]adj.超快的；超速的uniaxial[,juːnɪ'æksɪəl]adj.单轴的paraxial[pə'ræksɪəl]adj.旁轴的；近轴的periodicity[,pɪərɪə'dɪsɪtɪ]n.[数]周期性；频率；定期性soliton['sɔlitɔn]n.孤子，光孤子；孤立子；孤波discrete[dɪ'skriːt]adj.离散的，不连续的convolution[,kɒnvə'luːʃ(ə)n]n.卷积；回旋；盘旋；卷绕spontaneously:[spɒn'teɪnɪəslɪ] adv.自发地；自然地；不由自主地instantaneously:[,instən'teinjəsli]adv.即刻；突如其来地dielectricconstant[ˌdaiiˈlektrikˈkɔnstənt]介电常数，电容率chromatic[krə'mætɪk]adj.彩色的；色品的；易染色的aperture['æpətʃə;-tj(ʊ)ə]n.孔，穴；（照相机，望远镜等的）光圈，孔径；缝隙birefringence[,baɪrɪ'frɪndʒəns]n.[光]双折射radiant['reɪdɪənt]adj.辐射的；容光焕发的；光芒四射的; photomultiplier[,fəʊtəʊ'mʌltɪplaɪə]n.[电子]光电倍增管prism['prɪz(ə)m]n.棱镜；[晶体][数]棱柱theorem['θɪərəm]n.[数]定理；原理convex['kɒnveks]n.凸面体；凸状concave['kɒnkeɪv]n.凹面spin[spɪn]n.旋转；crystal['krɪst(ə)l]n.结晶，晶体；biconical[bai'kɔnik,bai'kɔnikəl] adj.双锥形的illumination[ɪ,ljuːmɪ'neɪʃən] n.照明；[光]照度；approximate[ə'prɒksɪmət] adj.[数]近似的；大概的clockwise['klɒkwaɪz]adj.顺时针方向的exponent[ɪk'spəʊnənt；ek-] n.[数]指数；even['iːv(ə)n]adj.[数]偶数的；平坦的；相等的eigenmoden.固有模式；eigenvalue['aɪgən,væljuː]n.[数]特征值cavity['kævɪtɪ]n.腔；洞，凹处groove[gruːv]n.[建]凹槽，槽；最佳状态；惯例；reciprocal[rɪ'sɪprək(ə)l]adj.互惠的；相互的；倒数的，彼此相反的essential[ɪ'senʃ(ə)l]adj.基本的；必要的；本质的；精华的isotropic[,aɪsə'trɑpɪk]adj,各向同性的；等方性的phonon['fəʊnɒn]n.[声]声子cone[kəʊn]n.圆锥体，圆锥形counter['kaʊntə]n.柜台；对立面；计数器；cutoff['kʌt,ɔːf]n.切掉；中断；捷径adj.截止的；中断的cladding['klædɪŋ]n.包层；interference[ɪntə'fɪər(ə)ns]n.干扰，冲突；干涉borderline['bɔːdəlaɪn]n.边界线，边界；界线quartz[kwɔːts]n.石英droplet['drɒplɪt]n.小滴，微滴precision[prɪ'sɪʒ(ə)n]n.精度，[数]精密度；精确inherently[ɪnˈhɪərəntlɪ]adv.内在地；固有地；holographic[,hɒlə'ɡræfɪk]adj.全息的；magnitude['mægnɪtjuːd]n.大小；量级；reciprocal[rɪ'sɪprək(ə)l]adj.互惠的；相互的；倒数的，彼此相反的stimulated['stimjə,letid]v.刺激（stimulate的过去式和过去分词）cylindrical[sɪ'lɪndrɪkəl]adj.圆柱形的；圆柱体的coordinates[kəu'ɔ:dineits]n.[数]坐标；external[ɪk'stɜːn(ə)l;ek-]n.外部；外观；scalar['skeɪlə]n.[数]标量；discretization[dɪs'kriːtaɪ'zeɪʃən]n.[数]离散化synthesize['sɪnθəsaɪz]vt.合成；综合isotropy[aɪ'sɑtrəpi]n.[物]各向同性；[物]无向性；[矿业]均质性pixel['pɪks(ə)l;-sel]n.（显示器或电视机图象的）像素（passive['pæsɪv]adj.被动的spiral['spaɪr(ə)l]n.螺旋；旋涡；equivalent[ɪ'kwɪv(ə)l(ə)nt]adj.等价的，相等的；同意义的; transverse[trænz'vɜːs;trɑːnz-;-ns-]adj.横向的；横断的；贯轴的;dielectric[,daɪɪ'lektrɪk]adj.非传导性的；诱电性的;n.电介质；绝缘体integral[ˈɪntɪɡrəl]adj.积分的；完整的criteria[kraɪ'tɪərɪə]n.标准，条件（criterion的复数）Dispersion:分散|光的色散spectroscopy[spek'trɒskəpɪ]n.[光]光谱学photovoltaic[,fəʊtəʊvɒl'teɪɪk]adj.[电子]光电伏打的，光电的polar['pəʊlə]adj.极地的；两极的；正好相反的transmittance[trænz'mɪt(ə)ns;trɑːnz-;-ns-] n.[光]透射比；透明度dichroic[daɪ'krəʊɪk]adj.二色性的；两向色性的confocal[kɒn'fəʊk(ə)l]adj.[数]共焦的；同焦点的rotation[rə(ʊ)'teɪʃ(ə)n]n.旋转；循环，轮流photoacoustic[,fəutəuə'ku:stik]adj.光声的exponential[,ekspə'nenʃ(ə)l]adj.指数的;fermion['fɜːmɪɒn]n.费密子（费密系统的粒子）semiconductor[,semɪkən'dʌktə]n.[电子][物]半导体calibration[kælɪ'breɪʃ(ə)n]n.校准；刻度；标度photodetector['fəʊtəʊdɪ,tektə]n.[电子]光电探测器interferometer[,ɪntəfə'rɒmɪtə]n.[光]干涉仪；干涉计static['stætɪk]adj.静态的；静电的；静力的;inverse相反的，反向的，逆的amplified['æmplifai]adj.放大的；扩充的horizontal[hɒrɪ'zɒnt(ə)l]n.水平线，水平面；水平位置longitudinal[,lɒn(d)ʒɪ'tjuːdɪn(ə)l;,lɒŋgɪ-] adj.长度的，纵向的；propagate['prɒpəgeɪt]vt.传播；传送；wavefront['weivfrʌnt]n.波前；波阵面scattering['skætərɪŋ]n.散射；分散telecommunication[,telɪkəmjuːnɪ'keɪʃ(ə)n] n.电讯；[通信]远程通信quantum['kwɒntəm]n.量子论mid-infrared中红外eigenvector['aɪgən,vektə]n.[数]特征向量；本征矢量numerical[njuː'merɪk(ə)l]adj.数值的；数字的ultraviolet[ʌltrə'vaɪələt]adj.紫外的；紫外线的harmonic[hɑː'mɒnɪk]n.[物]谐波。