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

Anion-conducting ionomer-based nanofibers mats are prepared by electrospinning (ES) technique. Depending on the relative humidity (RH) during the ES process (RH(ES)), 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 RH(ES) < 30% is discussed. The anion conductivity and WU of the ionomer electrospun mats prepared at the lowest RH(ES) are found to be higher than in those prepared at higher RH(ES). 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.