Electrospun Anion-Conducting Ionomer Fibers—Effect of Humidity on Final Properties

Abstract

Anion-conducting ionomer-based nanofibers mats are prepared by electrospinning (ES) technique. Depending on the relative humidity (RH) during the ES process (RHES), ionomer nanofibers with different morphologies are obtained. The effect of relative humidity on the ionomer nanofibers morphology, ionic conductivity, and water uptake (WU) is studied. A branching effect in the ES fibers found to occur mostly at RHES < 30% is discussed. The anion conductivity and WU of the ionomer electrospun mats prepared at the lowest RHES are found to be higher than in those prepared at higher RHES. This effect can be ascribed to the large diameter of the ionomer fibers, which have a higher WU. Understanding the effect of RH during the ES process on ionomer-based fibers’ properties is critical for the preparation of electrospun fiber mats for specific applications, such as electrochemical devices.

A Review on the Impact of Humidity during Electrospinning: From the Nanofiber Structure Engineering to the Applications

“…Branching effect was also observed by Halabi et al. [ 75 ] in the case of a ionomer, a quaternary ammonium functionalized aromatic poly (p‐phenylene oxide))‐based polymer, electrospun in DMF. In this case, branching occurred at RH ≤ 30% with much more branches at 30% than at 20%.…”

“…These processing conditions (i.e., low RH and addition of cations) were thus ideal to insure a high level of charges at the surface of the primary jet which is necessary for the emanation of secondary jets resulting finally to the fabrication of branched PVDF fibers. Branching effect was also observed by Halabi et al [75] in the case of a ionomer, a quaternary ammonium functionalized aromatic poly (p-phenylene oxide))-based polymer, electrospun in DMF. In this case, branching occurred at RH ≤ 30% with much more branches at 30% than at 20%.…”

Achieving High Conductivity at Low Ion Exchange Capacity for Anion Exchange Membranes with Electrospun Polyelectrolyte Nanofibers

“…In addition, the ionomer concentration of 38 wt % and RH of 40% also ensured smooth and uniform fiber formation. 65 From the surface morphology of the membrane (Figure 2b), it was observed that the membrane was dense, which guaranteed the low gas permeability, and a fiber network could be observed on the surface. There was no QPPONF identified from the fracture surface of the composite membrane (Figure 2c), indicating a very good compatibility between QPPONNF and the PVA matrix, which was crucial for the mechanical property and ion conductivity of the membrane.…”

Long-Period Fiber Grating Sensor Based on a Conductive Polymer Functional Layer

“…This type of functional coated layer is frequently employed as a feature in optical fiber sensors. A functional group of materials portrays a chemical or physical reaction with a purpose, for example, a small molecular structure grown layer-by-layer via deposition, or solution coating manufacture of a polymolecular structure by sol–gel or dip coating [ 3 , 4 , 5 ].…”