“…Polymer nanofibers are a class of fibers with diameter less than 1 μm. Because of extremely high specific surface area and highly porous structures provided by nanofibers, they have found use in many areas including sensors and biosensors, tissue engineering, drug delivery, filtration, energy storage, enzyme immobilization, composite reinforcement, protective clothing, sutures, and insulation . Nanofibers have been made using a variety of techniques, among which the electrospinning has generated enormous interest due to its simplicity, versatility, and continuous production capability .…”
Electroactive actuators based on conductive polymers currently have attracted a great deal of attention. In this study, a nanofibrous structure of polypyrrole (PPy) was used to fabricate an electroactive bending actuator. For this purpose, polyurethane/PPy (PU/PPy) nanofibrous bending actuator was fabricated through the combined use of electrospinning and in-situ chemical polymerization. The response surface methodology (RSM) was considered to find the optimal electrospinning conditions for producing PU nanofibers with the minimum diameter. The in-situ chemical polymerization method was then used to prepare a conductive layer of PPy on the surface of optimum electrospun nanofibers with p-toluenesulfonate (pTS) as the dopant. The coated nanofibers were used in the fabrication of PU/PPy-pTS nanofibrous bending actuator. The morphology and electrical, thermal, electrochemical, and electrochemomechanical properties of the fabricated actuator were investigated. By using optimum conditions of electrospinning, PU nanofibers were obtained with a diameter of 221 nm. The results showed that the produced PU/PPy-pTS nanofibers enjoy good thermal stability and have an electrical conductivity of about 276.34 S/cm. The obtained cyclic voltammetric and dynamo-voltammetric responses showed that the dominant mechanism of actuation in the fabricated PU/PPy-pTS nanofibrous actuator is the exchange of perchlorate anions with a partial exchange of lithium cations in 1M lithium perchlorate electrolyte solution. The fabricated actuator was capable of undergoing 141°r eversible angular displacement during a potential cycle. The results demonstrated that, given high porosity, large specific surface area, flexibility, and desirable electrical properties, PU/PPy nanofibrous electroactive actuator provides a lot of potential for developing artificial muscle applications.
“…Polymer nanofibers are a class of fibers with diameter less than 1 μm. Because of extremely high specific surface area and highly porous structures provided by nanofibers, they have found use in many areas including sensors and biosensors, tissue engineering, drug delivery, filtration, energy storage, enzyme immobilization, composite reinforcement, protective clothing, sutures, and insulation . Nanofibers have been made using a variety of techniques, among which the electrospinning has generated enormous interest due to its simplicity, versatility, and continuous production capability .…”
Electroactive actuators based on conductive polymers currently have attracted a great deal of attention. In this study, a nanofibrous structure of polypyrrole (PPy) was used to fabricate an electroactive bending actuator. For this purpose, polyurethane/PPy (PU/PPy) nanofibrous bending actuator was fabricated through the combined use of electrospinning and in-situ chemical polymerization. The response surface methodology (RSM) was considered to find the optimal electrospinning conditions for producing PU nanofibers with the minimum diameter. The in-situ chemical polymerization method was then used to prepare a conductive layer of PPy on the surface of optimum electrospun nanofibers with p-toluenesulfonate (pTS) as the dopant. The coated nanofibers were used in the fabrication of PU/PPy-pTS nanofibrous bending actuator. The morphology and electrical, thermal, electrochemical, and electrochemomechanical properties of the fabricated actuator were investigated. By using optimum conditions of electrospinning, PU nanofibers were obtained with a diameter of 221 nm. The results showed that the produced PU/PPy-pTS nanofibers enjoy good thermal stability and have an electrical conductivity of about 276.34 S/cm. The obtained cyclic voltammetric and dynamo-voltammetric responses showed that the dominant mechanism of actuation in the fabricated PU/PPy-pTS nanofibrous actuator is the exchange of perchlorate anions with a partial exchange of lithium cations in 1M lithium perchlorate electrolyte solution. The fabricated actuator was capable of undergoing 141°r eversible angular displacement during a potential cycle. The results demonstrated that, given high porosity, large specific surface area, flexibility, and desirable electrical properties, PU/PPy nanofibrous electroactive actuator provides a lot of potential for developing artificial muscle applications.
“…The decrease in the diameter of the core space is due to placement of coresheath nanofibre yarn in boiling water for one minute to dissolve the PVA nanofibres that led to lateral shrinkage of the hollow nanofibre yarn. Also, the process decreased the air gap between nanofibres resulting in nanofibre layers sticking together 17 .…”
Section: Resultsmentioning
confidence: 99%
“…The decrease in the diameter of the core space is due to placement of core-sheath nanofibre yarn in boiling water for one minute to dissolve the PVA nanofibres that led to lateral shrinkage of the hollow nanofibre yarn. Also, the process decreased the air gap between nanofibres resulting in nanofibre layers sticking together 17 . Figure 2 Scanning electron microscopy images of: (A) the cross section of quad-layered electrospun nanofibre yarn (B) the surface area of quad-layered electrospun nanofibre yarn, and (C) the cross-section area of hollow double-layered electrospun nanofibre yarn.…”
Section: Resultsmentioning
confidence: 99%
“…This core-sheath nanofibre consisted of PVA nanofibres as the core and nanofibres of nylon 6 as the sheath. Such yarn has potential applications in various fields such as loading drugs into a PVA solution as a core with variable portions 17 .…”
Urea is the most common form of nitrogenous fertiliser. Recently, research has focused on the development of delivery systems to prolong fertiliser release and prevent fertiliser loss through leaching and volatilization. This study investigates and compares single- and double-layered hollow nanofibrous yarns as novel delivery systems to encapsulate and release urea. Single-layered hollow poly l-lactic acid (PLLA) nanofibre yarns loaded with urea fertiliser were fabricated using a customized electrospinning. Double-layered hollow nanofibre yarns were produced by electrospinning polyhydroxybutyrate (PHB) nanofibres as an outer layer, with urea-impregnated PLLA nanofibres as the inner layer. Scanning electron microscopy (SEM) with an energy-dispersive spectroscopy (EDS) was used to characterize the morphology of hollow electrospun nanofibre yarns. A total nitrogen instrument (TNM-1) was used to study the urea release from single- and double-layered hollow nanofibres yarn in water. A Carbon:Nitrogen (CN) elemental analyser determined encapsulated nitrogen in PLLA nanofibres samples. Results indicated that urea-impregnated double-layered hollow nanofibre yarns significantly started nitrogen releasing at much lower amount during first 12 h compared to single-layered hollow nanofibre yarns (P value = 0.000). In conclusion, double-layered hollow nanofibre yarn has potential as an effective alternative to current methods for the slow release of fertilisers and other plant-required chemicals.
“…In the past decade, polymeric nanofibres have been used in a wide range of industrial and scientific applications [1,2]. The important properties of these nanostructures, including a very high specific surface area (about 1000 times higher than microfibres), flexibility in surface functionalities and desirable porosity and mechanical properties, have made them a suitable basic structure for many applications, such as tissue engineering [3], drug delivery [4], wound dressing [5,6], nanofibrous yarns for sutures [7][8][9], filtration [10,11], batteries [12], fuel cells [13], enzyme immobilization [14], sensors [15] and actuators [16]. Nanofibres can be produced through methods such as electrospinning, drawing, template synthesis, phase separation and self-assembly; but the simplicity of the electrospinning process and its ability to produce continuous nanofibres have drawn most of the attention to this technique of nanofibre production [17,18].…”
In this study, response surface methodology (RSM) based on the central composite design (CCD) was used for modelling the electrospinning process of polyacrylic acid (PAA) nanofibres, so as to assess simultaneously the effect of the most important electrospinning parameters (concentration of polymer solution, applied voltage, distance between the nozzle and collector and flow rate of solution) on the diameter of electrospun PAA nanofibres. The surface morphology was studied by scanning electron microscopy (SEM). The average diameter of PAA nanofibres obtained was from 233 to 1210 nm from SEM images with different process parameters. The results showed that the solution concentration, the applied voltage and the distance between the nozzle and collector are, in that order, the most important parameters affecting the diameter of nanofibres. The flow rate, however, showed no significant effect on the nanofiber diameter. The RSM model predicted that under optimal electrospinning conditions (solution concentration of 3 w/v%, voltage of 16 kV, electrospinning distance of 15 cm and flow rate of 1.75 ml h −1), the nanofibres would be 262 nm in diameter, which was proved to be very close to the actual measured value. Therefore, the obtained results demonstrated the good performance of the RSM model in investigating the effect of electrospinning variables and predicting the diameter of PAA nanofibres. PAA nanofibres have great potential in applications such as sensors and biosensors, removal of heavy metals and contaminants, muscle tissue engineering, etc. and the use of thinner nanofibres leads to their improved performance in these applications.
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