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

Summary

This paper describes a simple technique for coating electrospun PAN nanofibers with electroactive polymers using vapor deposition. The effects of the oxidant FeCl₃ 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.

Abstract

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 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 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 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.

Introduction

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 industries^1,2,3,4,5,6. Electrospinning is a voltage-driven fabrication tec....

Protocol

1. Experimental setup

1. Electrospinning of PAN nanofibers
   1. Dissolve 1 g of PAN in 10 mL of DMF to create a 10% solution.
   2. 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.
   3. Cover the metal collection drum, which will receive the polymer nanofibers, with wax paper for ea....

Discussion

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 electronics^1,

Materials

Name	Company	Catalog Number	Comments
10X PBS	Thermo Fisher Scientific	BP399-1	Used to mimic in vivo salt and humidity conditons
Acetone	Thermo Scientific	A412P4	Used to clean the VPD chamber
DMF	EMD Milipore Corporation	DX1727-6	Used as solvent to prepare PAN solutions
EDOT	TCI	E0741	Electroactive monomer used to deposit polymer on to PAN coupons
Electrospinning apparatus	SprayBase	ES30N-5W	Used to produce PAN nanofibers
FeCl3	Thermo Scientific	12357.22	Used to effect polymerization via chemical oxidation of electroactive monomers
Filter paper (180 μm)	VWR	28310-015	Used for filtration
High voltage power supply	Gamma	ES30N-5W	15KV-20KV. For this experiment 18.9KV was used.
Hot plate	Corning	PC420D	Used to heat vacuum chamber
Methanol	Fischer Chemical	A412-4	Used to remove FeCl2 and FeCl3 from EAP-coated PAN
Needle	BDYale	511098	20G
PAN powder	Ambeed	A971305	Used for the preparation of PAN nanofibers. Average MW 150,000 g/mol.
PTFE tubing	Microsolv Tech Corp.	49210-20-C	0.8 mm ID, 1.6 mm OD
Pump	Kozyvacu	ZK220419	Used for creating vacuum inside the chamber
Syringe	Air-Tite	231220	10 mL, disposable syringe
Syringe pump	New Era	NE-300	Flow rate 0.04 mL/min
Vacuum chamber with gauges	BAC Eng	X002APOXUR
Wax paper	Reynolds Kitchen	CM-3CY-06KR	Used to cover metal drum and collecting PAN nanofiber