This work was supported in part by the National Science Foundation Partnership for Research and Education in Materials (DMR#2122041) and the Alfred P. Sloan Foundation (# G-2022-19553) Texas State University/University of Colorado Boulder Sloan Undergraduate Research Program.

1. Experimental setup
<ol>
	<li>Electrospinning of PAN&#160;nanofibers
	<ol>
		<li>Dissolve 1 g of PAN in 10 mL of DMF to create a 10% solution.</li>
		<li>Assemble the electrospinning setup, ensuring that the high-voltage power supply, syringe pump, and a 20-gauge needle with a flat tip are connected to a grounded collector shown in Figure 1 and Figure 2. Ensure that the electrospinner is used in a fume hood or connected to ventilation ducting to minimize exposure to solvent vapors.</li>
		<li>Cover the metal collection drum, which will receive the polymer nanofibers, with wax paper for easy fiber retrieval and minimal cross-contamination between samples.</li>
		<li>Fill the syringe with the PAN solution and connect it to the spinneret needle using a 0.8 mm ID polytetrafluorethylene (PTFE) tube with Luer adapters.</li>
		<li>Set the flow rate of the syringe pump to 0.04 mL/min. The flow rate can be adjusted as needed depending on the polymer solution properties.</li>
		<li>Apply a voltage of 18.9 kV between the spinneret and the grounded collector, which is set to rotate at 1,200 rpm29,30. Follow proper guidelines during electrospinning as the process involves high voltage.</li>
		<li>Allow the charged jet to initiate from the spinneret, where it solidifies into continuous nanofibers as the solvent evaporates. Ensure that the applied voltage, solution flow rate, and drum rotation speed are consistent across all batches to achieve uniform fiber morphology and diameter.</li>
		<li>Allow the PAN nanofibers to deposit on the grounded collector coated with wax paper for approximately 4.5 h. After this time period, unwrap the wax paper from the drum by removing the tape.</li>
	</ol>
	</li>
	<li>Preparation of PAN coupons
	<ol>
		<li>Dry the PAN sheet mat in a vacuum desiccator at room temperature for 72 h to remove any residual solvent or water adsorbed during processing.</li>
		<li>Cut the dried fiber mats into 2 cm x 2 cm coupons with scissors or a razor blade. Note the positions of the coupons with respect to the direction of drum rotation, as shown in Figure 3. Organize coupons into groups of triplicates, producing replicates from the same column of the fiber mat to ensure consistency.</li>
	</ol>
	</li>
	<li>Vacuum system assembly
	<ol>
		<li>Assemble the chemical vapor phase deposition system using an enclosed steel container with a glass lid fitted with a silicone gasket to precisely control vacuum conditions, as shown in Figure 4.These containers are commercially available as vacuum degassing chamber kits from a variety of vendors and are inexpensive.</li>
		<li>Equip the system with two valves to manage the vacuum: one valve connects to the vacuum pump and is closed once the desired vacuum is reached; the other valve connects to the atmosphere and is opened to allow controlled release of the vacuum as needed.</li>
		<li>Connect a vacuum pump to the system to reduce the pressure in the chamber. Position the container on a hot plate capable of reaching temperatures up to 250 &#176;C to enable thermal management during the deposition process.</li>
	</ol>
	</li>
	<li>Vapor phase deposition rack assembly
	<ol>
		<li>Develop deposition racks for the project as per the designs for two deposition rack designs described below.</li>
		<li>Construct the Generation 1 (G1) deposition rack shown in Figure 5A by wrapping four vertical legs made of stainless steel in aluminum foil to prevent contamination.</li>
		<li>Connect the vertical legs with horizontal rods at the top and bottom, forming a hollow cube-like structure for stability.</li>
		<li>Wind three horizontal copper wires around the legs to create three tiers or levels for hanging the coupons.</li>
		<li>Ensure that the G1 rack is compact, fits within a processing chamber, and allows for easy assembly and disassembly.</li>
		<li>Construct the Generation 2 (G2) setup, shown in Figure 5B, using stainless steel for durability and corrosion resistance. Engineering schematics for this system are provided in Supplementary File 1. Design the G2 rack with a circular base and top plate connected by four vertical rods for stability and support. Equip the vertical rods with adjustable clamps to allow customization of the height between the base and top plate. Install a circular wire mesh tray made of stainless steel for hanging coupons.</li>
		<li>Ensure precise control over the positioning of electrospun coupons during the deposition process to promote uniform exposure to the vapor phase.</li>
	</ol>
	</li>
</ol>
2. Vapor phase deposition
<ol>
	<li>Deposition of FeCl3&#160;on PAN coupons
	<ol>
		<li>Weigh the PAN coupons. Deposit FeCl3 (oxidant) on the PAN coupons (at least three replicates per condition) by soaking them in aqueous FeCl3&#160;solutions of varying concentrations, ranging from 1 M to 5 M, for 30 min. 
		&#8203;CAUTION: Exercise caution when handling ferric chloride (anhydrous), as it is a corrosive irritant that can cause severe eye damage.</li>
		<li>Transfer the coupons onto low-lint paper wipes to facilitate osmotic drying, replacing the wipes 2x.</li>
		<li>Wrap the coupons in wipes and place them inside a fume hood for 24 h to complete the first stage of the drying process.</li>
		<li>Weigh the PAN coupons after 24 h and record the weight loss. Hang the PAN coupons by hooking them onto the metal wire tray prepared in step 1.4.9.</li>
		<li>Place a 500 mL beaker containing dry calcium chloride desiccant at the bottom of the setup. Position the entire setup inside a vacuum chamber.</li>
		<li>Initiate the vacuum by turning on the pump and leaving the vacuum valve open for continuous air removal, effectively using the vacuum system as a desiccator. Here, the pumping rate was 85 L/min. The final vacuum achieved by this pump and setup was approximately 8000 Pa.</li>
		<li>Monitor the weight loss of the coupons at intervals of 1 h, 2 h, 3 h, 24 h, 48 h, and 72 h.</li>
	</ol>
	</li>
	<li>PEDOT deposition onto PAN coupons
	<ol>
		<li>Hook and hang the PAN coupons on the coupon rack assembly.</li>
		<li>Suspend the coupons inside the vacuum system along with an open glass container holding approximately 4 g of the monomer (EDOT). Adjust the hot plate temperature to 55 &#176;C.</li>
		<li>Open the valve between the chamber and the vacuum pump and evacuate the chamber until the desired vacuum (8000 Pa) is achieved. Then, close the valve, leaving the chamber under vacuum.</li>
		<li>Allow the vapor deposition process to occur for 2 h. After 2 h, open the vacuum release valve to retrieve the PEDOT-coated coupons.</li>
	</ol>
	</li>
	<li>Coupon washing
	<ol>
		<li>Remove the polymer-coated coupons from the VPD chamber and transfer them to the washing chamber.</li>
		<li>Place the coupons over the opening of a porcelain funnel lined with circular filter paper of 5.5 cm in diameter and a pore size of 180 &#181;m, as shown in Figure 6.</li>
		<li>Wash each batch of three coupons of a specific concentration together to remove FeCl3&#160;residue by spraying methanol over the coupons using a squirt bottle.</li>
		<li>Ensure thorough removal of FeCl3&#160;residue by increasing methanol volume with higher concentrations to effectively dissolve and wash away residual oxidant and monomer. Use approximately 200 mL of methanol for coupons dipped in 1 M FeCl3. Increase the methanol amount by 50 mL for each higher concentration level (e.g., 250 mL for 2 M, 300 mL for 3 M).</li>
		<li>After washing, leave the coupons to dry under the hood for 30 min followed by drying in a desiccator with desiccant at room temperature for 1 h and finally preserve them in glass vials.</li>
	</ol>
	</li>
	<li>Cleaning of the VPD chamber and pump
	<ol>
		<li>Rinse the CVD chamber with acetone to dissolve the unreacted monomer. Dispose of the rinse in the organic waste container.</li>
		<li>Place the chamber in a fume hood while empty and heat it at 30 &#176;C for 1 h. Immerse the chamber in a detergent solution for 24 h and then dispose of the detergent.</li>
		<li>Heat the chamber with the lid slightly open at 200 &#176;C for 24 h. Perform another round of acetone spraying and dry the chamber in the fume hood at 30 &#176;C for 1 h.</li>
		<li>Change the pump oil after each batch of monomer deposition to maintain the integrity of the experiment.</li>
	</ol>
	</li>
</ol>
3. Characterization of samples
<ol>
	<li>SEM analysis of nanofiber mat
	<ol>
		<li>Attach PAN, PAN+FeCl3, and PAN+FeCl3+PEDOT samples to aluminum stubs using carbon tape.</li>
		<li>Image the samples at a magnification of 5000x, using a spot size of 4.5 nm and an accelerating voltage of 20 kV. Adjust imaging parameters as necessary to investigate sample morphology.</li>
		<li>Use the measurement function to determine fiber diameters. Take 12-15 measurements for a sample.</li>
		<li>Perform energy dispersive X-ray spectroscopy (EDS) analysis according to the standard operating procedures of the SEM instrument. Obtain the atomic percentage and weight percentage of the elements found in the samples.</li>
	</ol>
	</li>
	<li>Mechanical analysis
	<ol>
		<li>Laser cut 40 mm x 40 mm cardboard frames with 20 mm x 20 mm centered window openings.</li>
		<li>Using a razor blade, precisely cut out 10 mm x 40 mm nanofiber sample strips with the 40 mm edge being parallel to the direction of electrospun nanofiber formation.</li>
		<li>Measure the thickness (mm) of each strip using digital calipers at five locations chosen around the center of the specimen where the sample would not be in contact with the frame and about equal distances apart. Take the average as the thickness. Measure the weight (g) of each strip.</li>
		<li>Condition the sample either by desiccation (vacuum desiccator filled with calcium sulfate) or soaking in phosphate-buffered saline (10x PBS) for 72 h.</li>
		<li>Dab PBS-soaked samples on lint-free tissue wipes. Overlay a 10 mm x 40 mm polymer sample onto a 40 mm x 40 mm frame and tape it down for insertion into the tensile tester.</li>
		<li>Load the frame and sample into the tensile tester and test at room temperature and the desired strain rate (0.8 s-1). The output will be in force and displacement.</li>
		<li>Convert the force and displacement into stress-strain. Calculate the density of the sample from the sample dimensions and mass. To calculate stress, divide the force data collected by the tensile tester by the sample&#39;s cross-sectional area, then multiply by both the density of the fiber mat and the gauge length used while testing.</li>
	</ol>
	</li>
</ol>

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<li>Huang, Z. -M., Zhang, Y. -Z., Kotaki, M., Ramakrishna, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((A+review+on+polymer+nanofibers+by+electrospinning+and+their+applications+in+nanocomposites%5BTitle%5D)+AND+%22Compos+Sci+Technol%22%5BJournal%5D)">A review on polymer nanofibers by electrospinning and their applications in nanocomposites.</a> Compos Sci Technol. 63 (15), 2223-2253 (2003).</li>
<li>Koski, A., Yim, K., Shivkumar, S. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Effect+of+molecular+weight+on+fibrous+pva+produced+by+electrospinning%5BTitle%5D)+AND+%22Matter+Lett%22%5BJournal%5D)">Effect of molecular weight on fibrous pva produced by electrospinning.</a> Matter Lett. 58 (3-4), 493-497 (2004).</li>
<li>Fong, H., Chun, I., Reneker, D. H. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Beaded+nanofibers+formed+during+electrospinning%5BTitle%5D)+AND+%22Polymer%22%5BJournal%5D)">Beaded nanofibers formed during electrospinning.</a> Polymer. 40 (16), 4585-4592 (1999).</li>
<li>Liu, Y., He, J. H., Yu, J. Y., Zeng, H. M. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Controlling+numbers+and+sizes+of+beads+in+electrospun+nanofibers%5BTitle%5D)+AND+%22Polym+Int%22%5BJournal%5D)">Controlling numbers and sizes of beads in electrospun nanofibers.</a> Polym Int. 57 (4), 632-636 (2008).</li>
<li>Beachley, V., Wen, X. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Effect+of+electrospinning+parameters+on+the+nanofiber+diameter+and+length%5BTitle%5D)+AND+%22Matter+Sci+Eng+C%22%5BJournal%5D)">Effect of electrospinning parameters on the nanofiber diameter and length.</a> Matter Sci Eng C. 29 (3), 663-668 (2009).</li>
<li>Matthews, J. A., Wnek, G. E., Simpson, D. G., Bowlin, G. L. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Electrospinning+of+collagen+nanofibers%5BTitle%5D)+AND+%22Biomacromolecules%22%5BJournal%5D)">Electrospinning of collagen nanofibers.</a> Biomacromolecules. 3 (2), 232-238 (2002).</li>
<li>Asatekin, A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Designing+polymer+surfaces+via+vapor+deposition%5BTitle%5D)+AND+%22Mater+Today%22%5BJournal%5D)">Designing polymer surfaces via vapor deposition.</a> Mater Today. 13 (5), 26-33 (2010).</li>
<li>Butler, J. H., Joy, D. C., Bradley, G. F., Krause, S. J. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Low-voltage+scanning+electron+microscopy+of+polymers%5BTitle%5D)+AND+%22Polymer%22%5BJournal%5D)">Low-voltage scanning electron microscopy of polymers.</a> Polymer. 36 (9), 1781-1790 (1995).</li>
<li>Wu, J., Xiao, M., Quezada-Renteria, J. A., Hou, Z., Hoek, E. M. V. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Sample+preparation+matters%3A+Scanning+electron+microscopic+characterization+of+polymeric+membranes%5BTitle%5D)+AND+%22JMS+Letters%22%5BJournal%5D)">Sample preparation matters: Scanning electron microscopic characterization of polymeric membranes.</a> JMS Letters. 4 (1), 100073(2024).</li>
<li>El-Aufy, A. K. <a target="_blank" href="http://scholar.google.com/scholar?hl=en&safe=off&q=author%3aEl-Aufy%2C+AK+%22Nanofibers+and+nanocomposites+poly%283%2C4-ethylene+dioxythiophene%29%2Fpoly%28styrene+sulfonate%29+by+electrospinning%22">Nanofibers and nanocomposites poly(3,4-ethylene dioxythiophene)/poly(styrene sulfonate) by electrospinning</a>. , Drexel Universit. (2004).</li>
<li>Pires, L. S., Melo, D. S., Borges, J. P., Henriques, C. R. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Pedot-coated+pla+fibers+electrospun+from+solutions+incorporating+fe%28iii%29tosylate+in+different+solvents+by+vapor-phase+polymerization+for+neural+regeneration%5BTitle%5D)+AND+%22Polymers%22%5BJournal%5D)">Pedot-coated pla fibers electrospun from solutions incorporating fe(iii)tosylate in different solvents by vapor-phase polymerization for neural regeneration.</a> Polymers. 15 (19), 4004(2023).</li>
<li>Budday, S., Ovaert, T. C., Holzapfel, G. A., Steinmann, P., Kuhl, E. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Fifty+shades+of+brain%3A+A+review+on+the+mechanical+testing+and+modeling+of+brain+tissue%5BTitle%5D)+AND+%22Arch+Comput+Methods+Eng%22%5BJournal%5D)">Fifty shades of brain: A review on the mechanical testing and modeling of brain tissue.</a> Arch Comput Methods Eng. 27 (4), 1187-1230 (2020).</li>
<li>Pham, T. A., et al. <a target="_blank" href="http://www.ncbi.nlm.nih.gov/pubmed?term=((Investigation+on+the+microscopic%2Fmacroscopic+mechanical+properties+of+a+thermally+annealed+nafion+membrane%5BTitle%5D)+AND+%22Polymers%22%5BJournal%5D)">Investigation on the microscopic/macroscopic mechanical properties of a thermally annealed nafion membrane.</a> Polymers. 13 (22), 4018(2021).</li>
</ol>

The authors have nothing to disclose.

In this work, protocols for electrospinning nanofiber mats from commodity polymers, coating these nanofibers with electroactive polymers by vapor phase oxidative polymerization, and characterization of the chemical and mechanical properties of these materials are described.
Electrospinning has become a useful tool for the generation of high surface area materials for a range of applications from biomedicine to sustainability and electronics1,<sup class="xref"...

Electrospinning is a technique utilized for the fabrication of nanofiber-based materials for applications including tissue engineering, drug delivery, biosensing, food encapsulation, insulating materials, energy storage and dissipation, catalysis, and filtration. The versatility of this technique allows for different fiber arrangements and morphological structures, supporting innovations in multiple industries1,2,3,4,5,6. Electrospinning is a voltage-driven fabrication technique that produces small fibers from a polymer solution. The basic setup includes a syringe fitted with a spinneret (a stainless-steel needle or&#160;capillary extrusion tube) that is filled with a polymer solution, a syringe pump, a high-voltage power source, and a collector, as shown in Figure 1A. The syringe pump ensures a constant flow of the polymer solution. Using a rotating drum as a collector allows for the preparation of larger, more uniform fiber mats; rotation at low speeds yields randomly oriented fibers, while rotation at high speeds yields fibers oriented in the direction of drum rotation3. The speed necessary for fiber alignment is polymer solution-specific and can vary depending on factors such as solution viscosity, surface tension, and concentration. The process begins when an electric field is established between the needle tip and the collector, resulting in charges accumulating on the liquid surface. When electrostatic repulsion overcomes the surface tension, the liquid polymer solution forms a Taylor cone, leading to a jet of charged liquid moving toward the collector. As the solvent evaporates, solid polymer fibers are deposited onto the collector4,5. Electrospun nanofibers have been made from several polymers including polyacrylonitrile (PAN), polystyrene (PS), poly(vinyl alcohol) (PVA), polycaprolactone (PCL), poly(ethylene oxide) (PEO), poly(lactic-co-glycolic acid) (PLGA), nylon, poly(vinylidene fluoride)/polyurethane and polyvinylpyrrolidone1,7,8,9,10,11,12.
The fabrication of electrospun nanofiber-based materials using electroactive polymers (EAPs) is of particular interest. EAPs are materials with conjugated backbones that can be reversibly switched between multiple oxidation states using either chemical or electrochemical processes. This modification leads to changes in properties such as color, conductivity, reactivity, and volume13. This versatility makes EAPs well-suited for applications such as energy conversion and storage, electrochromics, actuators, sensors, and bioelectronics devices. EAP nanofibers, more specifically, have potential applications in energy storage, sensors, actuators, separations, nerve/tissue engineering, and biosensing14. Electroactive polymers (EAPs) pose several challenges during electrospinning due to their low viscosity and high conductivity which can hinder stable jet formation and lead to jet instability and bead formation instead of continuous fibers. Their sensitivity to electric fields can cause premature deformation or activation, resulting in inconsistent fiber formation. Additionally, EAPs typically suffer from poor solubility, requiring the use of specifically suitable solvents that affect solution viscosity, surface tension, and dielectric properties, complicating the process. The mechanical properties of EAPs, such as low elasticity and flexibility, can lead to jet breakage and fiber inconsistency. At the same time, the electrospinning process parameters, including voltage, needle-collector distance, and flow rate, need careful optimization, making the process more complex and less reproducible15,16,17,18. While there are several notable exceptions, in most cases, it is not possible to electrospin solutions of EAPs without the incorporation of additional polymers, called carrier polymers, that are capable of electrospinning19.
Alternative methods have been devised for the preparation of EAP nanofiber-based materials. Blending EAPs with other polymers or nanoparticles yields properties that are a hybrid of the two polymers1. While blending EAPs with carrier polymers enables electrospinning, the desirable properties of the EAP &#8212;&#160;notably its electroactivity (ability to change its properties in the presence of an electric field) and its conductivity &#8212; may be lost when blended. Instead, coating nonelectroactive electrospun nanofibers with EAPs can be a way to provide the electroactivity and conductivity of the EAP at the surface while having a mechanically robust polymer at the core of the nanofibers. EAP coatings can be accomplished using electrodeposition, spray coating, dip coating, or vapor-phase deposition. However, electrodeposition has several drawbacks. It requires conductive substrates, limiting its use with non-conductive materials unless they undergo pre-treatment to enhance conductivity. Achieving uniform coatings on complex or porous surfaces can be challenging due to uneven electric fields, resulting in variable deposition thicknesses. Controlling the morphology, thickness, and crystallinity of the coating also requires precise tuning of the electrolyte composition and applied voltage. Additionally, large-scale or three-dimensional objects may not receive uniform coatings, particularly in recessed areas. The risk of contamination from impurities in the electrolyte or on the electrode surface can introduce defects, while energy-intensive processes further complicate the technique19. Dip coating is a process where substrates are immersed in an EAP polymer solution and then withdrawn at a controlled rate to create a thin film. Alternatively, dip coating of a substrate with a monomer solution could be followed by a secondary polymerization step. The choice of solvent is critical; it must dissolve the polymer or monomer without dissolving the underlying fibers. However, the formation of non-conformal coatings or aggregation can be a drawback, particularly on complex surfaces. Spray coating efficiently covers large or complex surfaces and can be combined with other methods for multi-layer applications20, but spray coating also requires careful solvent selection to avoid dissolving the substrate polymers. Vapor phase deposition, specifically chemical vapor deposition (CVD), typically avoids solubility issues, produces uniform, thin coatings with excellent adhesion, allows coverage of complex geometries, and is a scalable process. CVD is a widely used method for uniformly coating substrates with various materials, such as carbon, metal oxides, and EAPs, by vaporizing precursors, transporting them to the substrate, and enabling adsorption, nucleation, and growth under controlled conditions. In the case of CVD of EAPs, the process typically involves vaporizing monomers and/or oxidants to enable in situ oxidative polymerization to take place onto the fibers. CVD offers advantages like uniform and conformal coatings, precise thin film formation, scalability for industrial applications, and versatility in material deposition, enhancing the functionality of nanofibers for diverse applications21. CVD was used by Zhu et al. for the coating of calcinated NiCo2O4 nanofibers originally made with polyvinylpyrrolidone with the EAP polypyrrole22.
In our work, nanofiber mats have been prepared from PAN as substrates for the CVD of EAPs. PAN is an inexpensive commodity polymer that is insoluble in aqueous media, is environmentally stable, and has high strength and modulus. Recent study by Sapountzi et al.23 has demonstrated the successful deposition of various materials on PAN nanofibers using CVD techniques. Specifically, they electrospun solutions of PAN containing the oxidant ferric chloride and then exposed the fibers to pyrrole and/or pyrrole-3-carboxylic acid vapors to produce core-shell nanofibers of PAN and EAPs for glucose sensing23.
In the CVD of EAPs, the concentration of oxidant is crucial to enable the oxidative polymerization of electroactive monomers like pyrrole and aniline onto electrospun nanofibers, significantly influencing the deposition rate and properties of the resulting conducting polymers. Ferric chloride (FeCl3) is commonly used as an oxidizing agent, forming monomer radical cations that react to create polymers24,25. Higher FeCl3 concentrations increase the polymerization and deposition rates due to more available oxidizing species, while lower concentrations slow these processes. Sapountzi et al. showed that higher FeCl3 concentrations resulted in faster deposition rates and more uniform coatings of polypyrrole (PPy) onto PAN nanofibers and vice versa23. With low FeCl3 concentrations, the limited availability of oxidizing species slows down the formation of radical cations and the subsequent polymerization process25,26. On the other hand, Xue et al. reported that an optimal FeCl3 concentration of 0.25 M resulted in a uniform and highly conductive PPy coating onto PAN nanofibers, while higher concentrations led to over-oxidation and degradation of the polymer27. Wissmann et al. studied the deposition of polyaniline (PANI) onto PAN nanofibers and observed that increasing the FeCl3 concentration from 0.1 M to 0.5 M significantly increased the deposition rate and conductivity of the PANI coating, but further increasing the concentration resulted in non-uniform deposition. Zhang et al. reported the deposition of a copolymer of aniline and o-anisidine onto PAN nanofibers using different FeCl3 concentrations. They found that an optimum FeCl3 concentration of 0.25 M resulted in a uniform and highly conductive coating, while higher concentrations led to over-oxidation and degradation of the polymer, as identified by the lower conductivity of the material28. Thus, careful selection of oxidant concentrations is critical to ensure optical EAP coatings.
This research demonstrates the use of CVD for the preparation of poly(3,4-ethylenedioxythiophene) (PEDOT)-coated PAN nanofibers. This research thus focuses on the process which involves electrospinning PAN nanofiber initially, followed first by infusing these PAN nanofibers with FeCl3 at various concentrations and then by the deposition of EAPs onto the FeCl3-ladden fibers, as shown in Figure 1. The study explores the influence of different concentrations of FeCl3 on the deposition rate of PEDOT onto the nanofibers. Mechanical testing assesses the effect of PEDOT coatings on the mechanical properties of the materials, particularly in high-humidity environments indicative of the material&#39;s pertinency to biomedical and water purification applications. The optimization of FeCl3 concentration is pivotal to ensuring efficient and precise deposition of EAPs, leading to uniform coatings and improved material properties. The absence of comprehensive studies examining the effects of FeCl3 concentrations and VPD setup characteristics on the deposition rate and functionality of EAP-coated PAN nanofibers underscores the significance of this research. The results of this work are especially significant given the differences observed in the EAP deposition at lower FeCl3 concentrations compared to previous studies, highlighting the critical role of the vapor phase deposition (VPD) setup.

<table><tbody><tr><td>10X PBS</td><td>Thermo Fisher Scientific</td><td>BP399-1</td><td>Used to mimic in vivo salt and humidity conditons</td></tr><tr><td>Acetone</td><td>Thermo Scientific&amp;nbsp;</td><td>A412P4</td><td>Used to clean the VPD chamber&amp;nbsp;</td></tr><tr><td>DMF</td><td>EMD Milipore Corporation</td><td>DX1727-6</td><td>Used as solvent to prepare PAN solutions</td></tr><tr><td>EDOT</td><td>TCI</td><td>E0741</td><td>Electroactive monomer used to deposit polymer on to PAN coupons</td></tr><tr><td>Electrospinning apparatus</td><td>SprayBase</td><td>ES30N-5W</td><td>Used to produce PAN nanofibers</td></tr><tr><td>FeCl&lt;sub&gt;3&lt;/sub&gt;</td><td>Thermo Scientific&amp;nbsp;&amp;nbsp;</td><td>12357.22</td><td>Used to effect polymerization via chemical oxidation of electroactive monomers</td></tr><tr><td>Filter paper (180 &amp;mu;m)</td><td>&amp;nbsp;VWR</td><td>28310-015</td><td>Used for filtration&amp;nbsp;</td></tr><tr><td>High voltage power supply</td><td>Gamma</td><td>ES30N-5W</td><td>15KV-20KV. For this experiment 18.9KV was used.</td></tr><tr><td>Hot plate</td><td>Corning</td><td>PC420D</td><td>Used to heat vacuum chamber</td></tr><tr><td>Methanol</td><td>Fischer Chemical</td><td>A412-4</td><td>Used to remove FeCl&lt;sub&gt;2&lt;/sub&gt; and FeCl&lt;sub&gt;3&lt;/sub&gt; from EAP-coated PAN</td></tr><tr><td>Needle</td><td>BDYale</td><td>511098</td><td>20G</td></tr><tr><td>PAN powder</td><td>Ambeed</td><td>A971305</td><td>Used for the preparation of PAN nanofibers. Average MW 150,000 g/mol.</td></tr><tr><td>PTFE tubing</td><td>Microsolv Tech Corp.</td><td>49210-20-C</td><td>0.8 mm ID, 1.6 mm OD</td></tr><tr><td>Pump</td><td>Kozyvacu</td><td>ZK220419</td><td>Used for creating vacuum inside the chamber</td></tr><tr><td>Syringe</td><td>Air-Tite</td><td>231220</td><td>10 mL, disposable syringe</td></tr><tr><td>Syringe pump</td><td>New Era</td><td>NE-300</td><td>Flow rate 0.04 mL/min</td></tr><tr><td>Vacuum chamber with gauges</td><td>BAC Eng</td><td>X002APOXUR</td><td></td></tr><tr><td>Wax paper</td><td>Reynolds Kitchen</td><td>CM-3CY-06KR</td><td>Used to cover metal drum and collecting PAN nanofiber</td></tr></tbody></table>

vapor phase deposition of electroactive poly(3,4-ethylenedioxythiophene) onto electrospun commodity polymer nanofibers

This study investigates the preparation of polyacrylonitrile (PAN) nanofibers through electrospinning to create highly porous and strong materials for applications in water purification, electrocatalysis, and biomedicine. The uniformly white PAN nanofiber mats were cut into 2 cm x 2 cm coupons to ensure consistency. After electrospinning, these nanofibers were coated with an electroactive polymer (EAP) using chemical vapor deposition, with iron (III) chloride (FeCl3) serving as an oxidant for polymerizing 3,4-ethylenedioxythiophene (EDOT) into poly(3,4-ethylenedioxythiophene) (PEDOT). The study examined the impact of different FeCl3 concentrations on PEDOT deposition on the PAN coupons. PEDOT deposition led to an increase in coupon weight. Scanning electron microscopy (SEM) revealed increases in the diameter of the nanofibers treated with increasing FeCl3 oxidant concentration, although higher FeCl3&#160;concentrations caused inter-fiber bridging, implying a concomitant decrease in inter-fiber spacing. Energy dispersive X-ray spectroscopy (EDS) was used to confirm the presence of Fe, Cl, and S in the nanofibers, with sulfur content rising with FeCl3&#160;concentration used, suggesting increased PEDOT deposition efficiency with increasing oxidant concentration. Mechanical testing showed that PEDOT-coated PAN fibers had improved tensile strength and toughness in the hydrated state compared to pure PAN nanofibers. These results highlight the crucial role of FeCl3&#160;concentration in influencing the morphology and properties of PAN-PEDOT composites, enhancing their suitability for applications such as water purification, tissue engineering, biosensing, catalysis, and energy storage.

In this work, electroactive polymer-coated PAN nanofibers are fabricated by electrospinning to develop highly porous yet strong materials that could be used as filters, absorbents, and photocatalysts for water purification, substrates for electrocatalysis, and scaffolds/matrices for tissue engineering, nerve regeneration, drug delivery, and biosensing. To provide these materials with electroactive properties, PAN nanofibers are coated with the EAP PEDOT by chemical vapor deposition.
<...

This paper describes a simple technique for coating electrospun PAN nanofibers with electroactive polymers using vapor deposition. The effects of the oxidant FeCl&#8323; on the deposition of poly(3,4-ethylenedioxythiophene) coatings on PAN were investigated to understand and optimize polymer growth, fiber diameter, and overall mechanical strength of the nanofiber mats.

Vapor Phase Deposition of Electroactive Poly(3,4-ethylenedioxythiophene) onto Electrospun Commodity Polymer Nanofibers

This study investigates the preparation of polyacrylonitrile (PAN) nanofibers through electrospinning to create highly porous and strong materials for ...

vapor-phase-deposition-electroactive-poly34-ethylenedioxythiophene

Research

JoVE Journal

Chemistry

676 Views.  Texas State University. Dit onderzoek onderzoekt het gebruik van chemische dampafzetting voor de bereiding van Poly(3, 4-ethyleendioxythiofeen)gecoate elektrogesponnen polyacrylonitril nanovezels om poreuze materialen te creëren voor toepassingen in de biogeneeskunde, waterzuivering en katalyse. Belangrijke uitdagingen zijn onder meer het voorkomen van vezeloverbrugging bij hoge zuurstofconcentraties, het optimaliseren van het wassen om achtergebleven ijzerchloride te verwijderen z...

Video: Dampfaseafzetting van elektroactief poly (3,4-ethyleendioxythiofeen) op elektrogesponnen polymeer nanovezels

Ambient Method for the Production of an Ionically Gated Carbon Nanotube Common Cathode in Tandem Organic Solar Cells

A method of fabricating organic photovoltaic (OPV) tandems that requires no vacuum processing is presented. These devices are comprised of two solution-processed polymeric cells connected in parallel by a transparent carbon nanotubes (CNT) interlayer. This structure includes improvements in fabrication techniques for tandem OPV devices. First the need for ambient-processed cathodes is considered. The CNT anode in the tandem device is tuned via ionic gating to become a common cathode. Ionic gating employs electric double layer charging to lower the work function of the CNT electrode. Secondly, the difficulty of sequentially stacking tandem layers by solution-processing is addressed. The devices are fabricated via solution and dry-lamination in ambient conditions with parallel processing steps. The method of fabricating the individual polymeric cells, the steps needed to laminate them together with a common CNT cathode, and then provide some representative results are described. These results demonstrate ionic gating of the CNT electrode to create a common cathode and addition of current and efficiency as a result of the lamination procedure.

A method of fabricating, in ambient conditions, organic photovoltaic tandem devices in a parallel configuration is presented. These devices feature an air-processed, semi-transparent, carbon nanotube common cathode.

A method of fabricating organic photovoltaic (OPV) tandems that requires no vacuum processing is presented. These devices are comprised of two ...

Engineering

Electroactive Polymer Nanoparticles Exhibiting Photothermal Properties

A method for the synthesis of electroactive polymers is demonstrated, starting with the synthesis of extended conjugation monomers using a three-step process that finishes with Negishi coupling. Negishi coupling is a cross-coupling process in which a chemical precursor is first lithiated, followed by transmetallation with ZnCl2. The resultant organozinc compound can be coupled to a dibrominated aromatic precursor to give the conjugated monomer. Polymer films can be prepared via electropolymerization of the monomer and characterized using cyclic voltammetry and ultraviolet-visible-near infrared (UV-Vis-NIR) spectroscopy. Nanoparticles (NPs) are prepared via emulsion polymerization of the monomer using a two-surfactant system to yield an aqueous dispersion of the polymer NPs. The NPs are characterized using dynamic light scattering, electron microscopy, and UV-Vis-NIR-spectroscopy. Cytocompatibility of NPs is investigated using the cell viability assay. Finally, the NP suspensions are irradiated with a NIR laser to determine their effectiveness as potential materials for photothermal therapy (PTT).

A protocol is presented for the synthesis and preparation of nanoparticles consisting of electroactive polymers.

A method for the synthesis of electroactive polymers is demonstrated, starting with the synthesis of extended conjugation monomers using a three-step ...

Electrospinning of Photocatalytic Electrodes for Dye-sensitized Solar Cells

This work demonstrates a protocol to fabricate a fiber-based photoanode for dye-sensitized solar cells, consisting of a light-scattering layer made of electrospun titanium dioxide nanofibers (TiO2-NFs) on top of a blocking layer made of commercially available titanium dioxide nanoparticles (TiO2-NPs). This is achieved by first electrospinning a solution of titanium (IV) butoxide, polyvinylpyrrolidone (PVP), and glacial acetic acid in ethanol to obtain composite PVP/TiO2 nanofibers. These are then calcined at 500 &#176;C to remove the PVP and to obtain pure anatase-phase titania nanofibers. This material is characterized using scanning electron microscopy (SEM) and powder X-ray diffraction (XRD). The photoanode is prepared by first creating a blocking layer through the deposition of a TiO2-NPs/terpineol slurry on a fluorine-doped tin oxide (FTO) glass slide using doctor blading techniques. A subsequent thermal treatment is performed at 500 &#176;C. Then, the light-scattering layer is formed by depositing a TiO2-NFs/terpineol slurry on the same slide, using the same technique, and calcinating again at 500 &#176;C. The performance of the photoanode is tested by fabricating a dye-sensitized solar cell and measuring its efficiency through J-V curves under a range of incident light densities, from 0.25-1 Sun.

The overall goal of this project was to use electrospinning to fabricate a photoanode with improved performance for dye-sensitized solar cells.

This work demonstrates a protocol to fabricate a fiber-based photoanode for dye-sensitized solar cells, consisting of a light-scattering layer made of ...

Reactive Vapor Deposition of Conjugated Polymer Films on Arbitrary Substrates

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. Conductive polymers, poly(3,4-ethylenedioxythiophene) (PEDOT) and poly(3,4-propylenedioxythiophene) (PProDOT), and a semiconducting polymer, poly(thieno[3,2-b]thiophene) (PTT), were deposited on unconventional highly-disordered and textured substrates with high surface areas, such as paper, towels and fabrics. This reported deposition chamber is an improvement of previous vapor reactors because our system can accommodate both volatile and nonvolatile monomers, such as 3,4-propylenedioxythiophene and thieno[3,2-b]thiophene. Utilization of both solid and liquid oxidants are also demonstrated. One limitation of this method is that it lacks sophisticated in situ thickness monitors. Polymer coatings made by the commonly used solution-based coating methods, such as spin-coating and surface grafting, are often not uniform or susceptible to mechanical degradation. This reported vapor phase deposition method overcomes those drawbacks and is a strong alternative to common solution-based coating methods. Notably, polymer films coated by the reported method are uniform and conformal on rough surfaces, even at a micrometer scale. This feature allows for future application of vapor deposited polymers in electronics devices on flexible and highly textured substrates.

This paper presents a protocol for reactive vapor deposition of poly(3,4-ethylenedioxythiophene), poly(3,4-propylenedioxythiophene), and poly(thieno[3,2-b]thiophene) films on glass slides and rough substrates, such as textiles and paper.

We demonstrate a method of conformally coating conjugated polymers on arbitrary substrates using a custom-designed, low-pressure reaction chamber. ...

Electrospun Nanofiber Scaffolds with Gradations in Fiber Organization

The goal of this protocol is to report a simple method for generating nanofiber scaffolds with gradations in fiber organization and test their possible applications in controlling cell morphology/orientation. Nanofiber organization is controlled with a new fabrication apparatus that enables the gradual decrease of fiber organization in a scaffold. Changing the alignment of fibers is achieved through decreasing deposition time of random electrospun fibers on a uniaxially aligned fiber mat. By covering the collector with a moving barrier/mask, along the same axis as fiber deposition, the organizational structure is easily controlled. For tissue engineering purposes, adipose-derived stem cells can be seeded to these scaffolds. Stem cells undergo morphological changes as a result of their position on the varied organizational structure, and can potentially differentiate into different cell types depending on their locations. Additionally, the graded organization of fibers enhances the biomimicry of nanofiber scaffolds so they more closely resemble the natural orientations of collagen nanofibers at tendon-to-bone insertion site compared to traditional scaffolds. Through nanoencapsulation, the gradated fibers also afford the possibility to construct chemical gradients in fiber scaffolds, and thereby further strengthen their potential applications in fast screening of cell-materials interaction and interfacial tissue regeneration. This technique enables the production of continuous gradient scaffolds, but it also can potentially produce fibers in discrete steps by controlling the movement of the moving barrier/mask in a discrete fashion.

Here, we present a protocol to fabricate electrospun nanofiber scaffolds with gradated organization of fibers and explore their applications in regulating cell morphology/orientation. Gradients with regard to physical and chemical properties of the nanofiber scaffolds offer a wide variety of applications in the biomedical field.

The goal of this protocol is to report a simple method for generating nanofiber scaffolds with gradations in fiber organization and test their possible ...

Bioengineering

Adapting the Electrospinning Process to Provide Three Unique Environments for a Tri-layered In Vitro Model of the Airway Wall

Electrospinning is a highly adaptable method producing porous 3D fibrous scaffolds that can be exploited in in vitro cell culture. Alterations to intrinsic parameters within the process allow a high degree of control over scaffold characteristics including fiber diameter, alignment and porosity. By developing scaffolds with similar dimensions and topographies to organ- or tissue-specific extracellular matrices (ECM), micro-environments representative to those that cells are exposed to in situ can be created. 
The airway bronchiole wall, comprised of three main micro-environments, was selected as a model tissue. Using decellularized airway ECM as a guide, we electrospun the non-degradable polymer, polyethylene terephthalate (PET), by three different protocols to produce three individual electrospun scaffolds optimized for epithelial, fibroblast or smooth muscle cell-culture. Using a commercially available bioreactor system, we stably co-cultured the three cell-types to provide an in vitro model of the airway wall over an extended time period.
This model highlights the potential for such methods being employed in in vitro diagnostic studies investigating important inter-cellular cross-talk mechanisms or assessing novel pharmaceutical targets, by providing a relevant platform to allow the culture of fully differentiated adult cells within 3D, tissue-specific environments.

Adapting the Electrospinning Process to Provide Three Unique Environments for a Tri-layered In Vitro Model of the Airway Wall

Advancements in biomaterial technologies enable the development of three-dimensional multi-cell-type constructs. We have developed electrospinning protocols to produce three individual scaffolds to culture the main structural cells of the airway to provide a 3D in vitro model of the airway bronchiole wall.

Electrospinning is a highly adaptable method producing porous 3D fibrous scaffolds that can be exploited in in vitro cell culture. Alterations to ...

Fabricating Degradable Thermoresponsive Hydrogels on Multiple Length Scales via Reactive Extrusion, Microfluidics, Self-assembly, and Electrospinning

While various smart materials have been explored for a variety of biomedical applications (e.g., drug delivery, tissue engineering, bioimaging, etc.), their ultimate clinical use has been hampered by the lack of biologically-relevant degradation observed for most smart materials. This is particularly true for temperature-responsive hydrogels, which are almost uniformly based on polymers that are functionally non-degradable (e.g., poly(N-isopropylacrylamide) (PNIPAM) or poly(oligoethylene glycol methacrylate) (POEGMA)). As such, to effectively translate the potential of thermoresponsive hydrogels to the challenges of remote-controlled or metabolism-regulated drug delivery, cell scaffolds with tunable cell-material interactions, theranostic materials with the potential for both imaging and drug delivery, and other such applications, a method is required to render the hydrogels (if not fully degradable) at least capable of renal clearance following the required lifetime of the material. To that end, this protocol describes the preparation of hydrolytically-degradable hydrazone-crosslinked hydrogels on multiple length scales based on the reaction between hydrazide and aldehyde-functionalized PNIPAM or POEGMA oligomers with molecular weights below the renal filtration limit. Specifically, methods to fabricate degradable thermoresponsive bulk hydrogels (using a double barrel syringe technique), hydrogel particles (on both the microscale through the use of a microfluidics platform facilitating simultaneous mixing and emulsification of the precursor polymers and the nanoscale through the use of a thermally-driven self-assembly and cross-linking method), and hydrogel nanofibers (using a reactive electrospinning strategy) are described. In each case, hydrogels with temperature-responsive properties similar to those achieved via conventional free radical cross-linking processes can be achieved, but the hydrazone cross-linked network can be degraded over time to re-form the oligomeric precursor polymers and enable clearance. As such, we anticipate these methods (which may be generically applied to any synthetic water-soluble polymer, not just smart materials) will enable easier translation of synthetic smart materials to clinical applications.

Protocols are described for the fabrication of degradable thermoresponsive hydrogels based on hydrazone cross-linking of polymeric oligomers on the bulk scale, microscale, and nanoscale, the latter for preparation of both gel nanoparticles and nanofibers.

While various smart materials have been explored for a variety of biomedical applications (e.g., drug delivery, tissue engineering, bioimaging, etc.), ...

Solution Blow Spinning of Polymeric Nano-Composite Fibers for Personal Protective Equipment

Light-weight, protective armor systems typically consist of high modulus (&#62;109 MPa) and high-strength polymeric fibers held in place with an elastic resin material (binder) to form a non-woven, unidirectional laminate. While significant efforts have focused on improving the mechanical properties of the high-strength fibers, little work has been undertaken to improve the properties of the binder materials. To improve the performance of these elastomeric polymer binders, a relatively new and simple fabrication process, known as solution blow spinning, was used. This technique is capable of producing sheets or webs of fibers with average diameters ranging from the nanoscale to the microscale. To achieve this, a solution blow spinning (SBS) apparatus has been designed and built in the laboratory to fabricate non-woven fiber mats from polymer elastomer solutions.
In this study, a commonly used binder material, a styrene-butadiene-styrene block-co-polymer dissolved in tetrahydrofuran, was used to produce nanocomposite fiber mats by adding metallic nanoparticles (NPs), such as iron oxide NPs, that were encapsulated with silicon oil and thus incorporated in the fibers formed via the SBS process. The protocol described in this work will discuss the effects of the various critical parameters involved in the SBS process, including the polymer molar mass, the selection of the thermodynamically appropriate solvent, the polymer concentration in solution, and the carrier gas pressure to assist others in performing similar experiments, as well as provide guidance to optimize the configuration of the experimental setup. The structural integrity and morphology of the resultant non-woven fiber mats were examined using scanning electron microscopy (SEM) and elemental X-ray analysis via energy-dispersive X-ray spectroscopy (EDS). The goal of this study is to evaluate the effects of the various experimental parameters and material selections to optimize the structure and morphology of the SBS fiber mats.

The primary goal of this study is to describe a protocol to prepare polymeric fiber mats with consistent morphology via solution blow spinning (SBS). We aim to use SBS to develop novel, tunable, flexible polymeric fiber nanocomposites for various applications, including protective materials, by incorporating nanoparticles in a polymer-elastomer matrix.

Light-weight, protective armor systems typically consist of high modulus (&#62;109 MPa) and high-strength polymeric fibers held in place with an elastic ...

Electrochemical Preparation of Poly(3,4-Ethylenedioxythiophene) Layers on Gold Microelectrodes for Uric Acid-Sensing Applications

Two different methods for the synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) on gold electrodes are described, using electropolymerization of 3,4-ethylenedioxythiophene (EDOT) monomer in an aqueous and an organic solution. Cyclic voltammetry (CV) was used in the synthesis of PEDOT thin layers. Lithium perchlorate (LiClO4) was used as a dopant in both aqueous (aqueous/acetonitrile (ACN)) and organic (propylene carbonate (PC)) solvent systems. After the PEDOT layer was created in the organic system, the electrode surface was acclimatized by successive cycling in an aqueous solution for use as a sensor for aqueous samples. 
The use of an aqueous-based electropolymerization method has the potential benefit of removing the acclimatization step to have a shorter sensor preparation time. Although the aqueous method is more economical and environmentally friendly than the organic solvent method, superior PEDOT formation is obtained in the organic solution. The resulting PEDOT electrode surfaces were characterized by scanning electron microscopy (SEM), which showed the constant growth of PEDOT during electropolymerization from the organic PC solution, with rapid fractal-type growth on gold (Au) microelectrodes.

Electrochemical Preparation of Poly3,4-Ethylenedioxythiophene Layers on Gold Microelectrodes for Uric Acid-Sensing Applications

We describe aqueous and organic solvent systems for the electropolymerization of poly(3,4-ethylenedioxythiophene) to create thin layers on the surface of gold microelectrodes, which are used for sensing low molecular weight analytes.

Two different methods for the synthesis of poly(3,4-ethylenedioxythiophene) (PEDOT) on gold electrodes are described, using electropolymerization of ...

A Simple and Scalable Fabrication Method for Organic Electronic Devices on Textiles

Today, wearable electronics devices combine a large variety of functional, stretchable, and flexible technologies. However, in many cases, these devices cannot be worn under everyday conditions. Therefore, textiles are commonly considered the best substrate to accommodate electronic devices in wearable use. In this paper, we describe how to selectively pattern organic electroactive materials on textiles from a solution in an easy and scalable manner. This versatile deposition technique enables the fabrication of wearable organic electronic devices on clothes.

In this paper, we present a protocol to selectively deposit organic materials on textiles, which allows for the direct integration of organic electronic devices with wearables. The fabricated devices can be fully integrated in textiles, respecting their mechanical appearance and enabling sensing capabilities.

Today, wearable electronics devices combine a large variety of functional, stretchable, and flexible technologies. However, in many cases, these devices ...

Vapor Phase Deposition of Electroactive Poly(3,4-ethylenedioxythiophene) onto Electrospun Commodity Polymer Nanofibers

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