Electroless deposition of thin metallic films on polymer fibers prepared via electrospinning (original) (raw)
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Journal of Applied Polymer Science, 2009
Poly(vinyl alcohol) (PVOH) was electrospun using different methods to charge the polymer solution. A positive high voltage relative to the collecting electrode significantly increased the fiber deposition rate. Electron microscopy showed that approximately half of the increase in fiber mass was due to thicker fibers being deposited. The current flowing from the grounded electrode was measured to determine the charge carried on the PVOH jet. This showed that for a positive voltage charging condition there is a much larger current and hence more charge carriers generated in the PVOH solution. As a result, more mass is ejected from the Taylor cone, implying that a positive voltage also produces longer fiber for a given time period. We also tested whether different substrate materials caused any variation when the charging conditions were changed. Statistically significant variation between substrates was only found when the substrate was an insulator and was expected to support a high-deposition rate. This confirms the view that the PVOH fiber arrives at the collecting electrode carrying a charge that must be neutralized, otherwise a repulsive charge will form where the fiber is deposited and some fiber will be lost to any alternative earth. In electrospraying, charge carriers are generated using associated redox reactions. Thus, for electrospinning a lack of symmetry in these reactions may result in the generation of different quantities of charge carriers in the PVOH solution and changes in the mass deposition rate of electrospun fiber. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009
The aim of this paper is to develop metal coated textile fibres for application in textile electrodes and as a substrate for further functionalisation of the fibres. A polyaramide woven structure was used as substrate and selected because of its excellent mechanical properties and thermal resistivity. Direct plating of copper at this substrate did not give good results, therefore first polypyrrole was deposited chemically. The deposition steps are optimized in this investigation and the obtained layers are characterized with different methods. Typical thicknesses of 0.5 to 3 μm were obtained for polypyrrole and copper layers, which were dependent of the deposition time. The coated fibre structures showed excellent electroconductive properties.
materials Electrospun Polymer Fibers for Electronic Applications
Nano-and micro-fibers of conjugated polymer semiconductors are particularly interesting both for applications and for fundamental research. They allow an investigation into how electronic properties are influenced by size confinement and chain orientation within microstructures that are not readily accessible within thin films. Moreover, they open the way to many applications in organic electronics, optoelectronics and sensing. Electro-spinning, the technique subject of this review, is a simple method to effectively form and control conjugated polymer fibers. We provide the basics of the technique and its recent advancements for the formation of highly conducting and high mobility polymer fibers towards their adoption in electronic applications.
Electrically Conductive Fibre Substrates
2014
Textiles are an aggregation of fibres in various forms and fibres are made up of polymeric chains that are little known to conduct electricity. However, these offer advantage of flexibility and ease of making-up, hence have found their way to make conductive material. The term electro-textiles, known as E-textiles, refer to fabrics that can function electrically as electronics and behave physically as textiles. The paper discusses the basics of conductivity in solids, especially metals and fibres like carbon. It then reviews the various techniques that have been adopted to improve the electrical conductivity of fibre substrates viz., use of conductive materials as fibres, yarns or threads, coating with conductive materials and using an inherently conductive material/polymer. The advantages and limitations of each of the methods have been discussed. Further the paper highlights the categories of conductive fibre substrates based on their electrical resistance and the various applicat...
Fibers and Polymers, 2015
In this study, three different free surface electrospinning methods: Splashing electrospinning, spiral coil electrospinning and rotary wires electrospinning methods were explored and compared in terms of fiber morphology (diameter fiber and its distribution) and process parameters. It was found that higher voltage values between 45 kV to 60 kV were necessary for Splashing electrospinning method while voltage values ranged between 50 kV to 70 kV and voltage values between 40 kV and 60 kV were enough for spiral coil and straight wires electrospinning methods, respectively. The real impact of process parameters and the evaluation of the influence of combined various processing parameters on electrospun fiber were undertaken. The results analysis demonstrates that two combined parameters based investigation can help provide insight into how to control and improve the design of the electrospinning process. The fiber diameter and its distribution can be effectively minimized either by controlling the processing parameters to a certain level. The nonlinearity relationship existing between electrospinning process parameters and nanofiber diameter and its distribution has been illustrated. It has also been observed that electric field plays a crucial role in the successful free surface electrospinning.
Electrospinning: the challenges in developing nanometer-scale fibers and their applications in materials engineering (Atena Editora), 2024
Electrospinning is a material processing technique used to produce nanofibers through the application of an electric field and has an interesting history full of developments over time. From its first applications to the most recent advances, electrospinning has been the subject of intense research and study. Over the years, interest in the technique has grown considerably, reflected in the significant increase in the number of scientific publications on the subject. This exponential growth in the volume of research demonstrates the importance and relevance of this technique in science and industry. There is a wide range of options regarding materials that can be electrospun, such as polymers, metals and ceramics, which are just a few examples of the materials that can be transformed into nanofibers through this process. Such diversity offers several possibilities for different applications, through the prior study and adjustment of electrospinning operational parameters that play a fundamental role in determining the characteristics of the nanofibers produced. Factors such as voltage, flow rate and distance between needle and collector can be regulated to control nanofiber properties such as diameter, morphology and distribution. The applications of the produced nanofibers cover a variety of fields. In medicine, tissue engineering, electronic devices, nanofibers serve as a framework for the new design and improvement of many technologies, such as air and water filtration, flexible electronics, piezoelectric and gas detection sensors, photovoltaic devices, materials composites for adsorption, among other fields.
Positioning and Aligning Electrospun PAN Fibers by Conductive and Dielectric Substrate Patterns
Macromolecular Symposia, 2021
During electrospinning, the flying nanofibers can be attracted by conductive areas such as copper tape on a nonconductive substrate, especially in case of magnetic nanofibers. The question arises, however, whether the conductivity or any other physical properties of these areas are responsible for this effect. Here, electrospinning polyacrylonitrile (PAN) on nonconductive polypropylene (PP) substrates is reported, modified with conductive copper tape as well as with diverse coatings with varying dielectric constants. The results show that in case of non-magnetic PAN fibers, especially BaTiO 3 with its high dielectric constant strongly, attracts the fibers formed during electrospinning, which can be explained by local modification of the electric field due to the introduced dielectric. This process can be used to tailor the nanofiber mat thickness depending on the position.
Characterization of an electrospinning process using different PAN/DMF concentrations
Polimeros-ciencia E Tecnologia, 2007
We performed an extensive characterization of an electrospinning process to evaluate how the process parameters and precursor solution characteristics affect the fibers morphology. The work was conducted using precursor solutions with different concentrations of polyacrylonitrile (PAN) diluted in a fixed amount of N,N/dimethylformamide (DMF). Fibers obtained with this process can find important applications in the field of nanosensors. The characteristics of the electrospun fibers were analyzed as a function of the solution viscosity, applied voltage and distance between the needle tip (positive electrode) and the collector plate (grounded electrode). The electrical current was monitored during the deposition process and its behavior was correlated with the characteristics of the fibers obtained. Our results demonstrate that the diameter of the fibers increases with increasing viscosity and applied voltage. The number of deposited fibers also increases with the applied voltage. Also, viscosity and applied voltage strongly affect the shape, length and morphology of the fibers. Of particular interest, we demonstrated that by monitoring the electrical current it is possible to control the fibers morphology and bead concentration. The distance between tip and collector plate determines the way the fibers arrive on the collector plate. A main contribution of this study was the definition of conditions to controllably obtain fibers that are smooth and that present diameters in the range between 140 and 300 nm.
Production of core/shell fibers by electrospinning from a free surface
Chemical Engineering Science, 2013
Electrostatic fiber formation ("electrospinning") is the leading technology for production of continuous fibers with submicron diameter. Applications such as drug delivery and sensors benefit from the ability to produce submicron fibers with a core/shell morphology from electrified coaxial jets of two liquids. However, low productivity of the conventional needlebased coaxial process is a barrier for commercialization. We present a novel technology that overcomes this limitation by the development of coaxial jets directly from compound droplets of immiscible liquids entrained on wires, and control of mass transfer processes to produce uniform, core/shell fibers. The enabling feature of controlled evaporation by design of solution properties is verified by a simple mass transfer model. Electron micrographs confirm the formation of fibers with the desired morphology. The proposed technology creates the opportunity to produce nanofibers with core/shell morphology on an industrial scale for a wide variety of applications.