Substrate effect on the swelling and water sorption of Nafion nanomembranes

Measurement of water uptake in thin-film Nafion and anion alkaline exchange membranes using the quartz crystal microbalance

“…Water transport across SPEs is driven by several mechanisms, including diffusion by activity gradients, convection through hydraulic pressure differences and electro-osmotic drag. Water uptake and transport through PEMs, and specifically Nafion, has been extensively studied; however, the microstructure of hydrated Nafion is currently a subject of intense study and speculation [4]; the most established theory is the Cluster-Network model presented in the 1980s [5][6][7]. The Cluster-Network model considers the ionomer as a network of ionic clusters formed by the sulphonic groups arranged as inverted micelles (roughly 4 nm diameter) and interconnected by narrow water channels (1 nm in diameter).…”

“…The study of thin film (o1000 nm) Nafion ionomers has been explored in a limited capacity and remains somewhat ambiguous [4,11,12]. Characterisation work presented by Wood et al [13] Karan and co-workers [14,15] as well as Dishari and Hickner [16] have shown the presence of an ultra-thin o 55 nm hydrophilic layer developed on self-assembled thin film Nafion ionomers.…”

Membranes for Direct Alcohol Fuel Cells

“…Interestingly, the conductivity of commercial Nafion films (112,115, and 117) lies on the same line that recast Nafion membranes, while the activation energy for the proton conductivity increases from~15 kJ.mol À1 for thick membranes (100 μm) up to 30 and 50 kJ.mol À1 for the thinnest membranes (< 100 NM) AT 85 % AND 60 % RH, respectively. The authors suggested that the lower conductivity of thin membranes is due to a reduction of water uptake, with the consequent increase in activation energy for proton, transport, a fact that has been confirmed recently [317]. These results are relevant to the description of the charge transport in the ionomer within the three phase boundary region, which will be discussed later in this Chapter.…”

“…There are multiple examples of membranes with very high β r values, which exhibit very poor fuel cell performances. That means that the architecture of the three phases region is probably the bottleneck of the MEA performance and much attention should be paid to the properties of the ionomeric material use as a binder, forming nanometric structures whose properties could be rather different than those of the bulk materials [317]. Consequently, the properties of very thin films of ionomeric membranes on carbon and metal substrates should be studied for enhancing the performance of direct alcohol fuel cells.…”

Effect of humidity on the interaction of CO2 with alkaline anion exchange membranes probed using the quartz crystal microbalance

“…This investigation uses thin film (65 ± 4 nm) drop cast ionomers for each study to ensure that the deposited mass is within the QCM's operable range [29], and to minimise contribution from internal water diffusion from the bulk when operating through the investigative range of relative humidities [28,32,33].…”