Free volume, gas permeation, and proton conductivity in MIL-101-SO₃H/Nafion composite membranes

Abstract

The influence of free volume size on the gas permeability of MIL-101-SO3H/Nafion composite membranes is closely related to the size of the particular gas molecules.

Positron annihilation lifetime study of subnano level free volume features of grafted polymer electrolyte membranes for hydrogen fuel cell applications

“…These facts explain why the significant increase of I 2 and remarkable decrease of I 3 and I 4 are detected. A similar inhibition effect was also observed in Nafion 19–22 and other graft‐type sulfonated membranes 23 …”

“…On the basic of the relatively small size Ps probe, the experimentally measured o‐ Ps lifetime can be utilized to investigate the free‐volume hole features in polymers. So far, only several studies have utilized the PALS to probe the microstructures of alternative PEMs, 8,16–18 whereas most of the attention is focused on the commercial Nafion membranes and their composites 19–22 . Moreover, there is only one work on the graft‐type PEMs, 23 leading to a very limited understanding of the subnano holes and their relation to the fuel cell performance.…”

“…Moreover, there is only one work on the graft‐type PEMs, 23 leading to a very limited understanding of the subnano holes and their relation to the fuel cell performance. In addition to relating the lifetime and intensity of o ‐Ps to free volume, many works have further investigated relating the o ‐Ps parameters to different characteristics of PEMs such as molecular weight or ion exchange capacity (IEC), 18,21 water, methanol, and gas permeability, 17,19–22 proton conductivity, 17,21–23 crystallinity, 21 mechanical property, 8 and so forth. However, there have been no reports on the above relations for the graft‐type PEMs.Recently, the ETFE‐PEMs have been investigated extensively by our group 5,6,24–28 and others 29–32 .…”

“…So far, only several studies have utilized the PALS to probe the microstructures of alternative PEMs, 8,[16][17][18] whereas most of the attention is focused on the commercial Nafion membranes and their composites. [19][20][21][22] Moreover, there is only one work on the graft-type PEMs, 23 leading to a very limited understanding of the subnano holes and their relation to the fuel cell performance. In addition to relating the lifetime and intensity of o-Ps to free volume, many works have further investigated relating the o-Ps parameters to different characteristics of PEMs such as molecular weight or ion exchange capacity (IEC), 18,21 water, methanol, and gas permeability, 17,19-22 proton conductivity, 17,21-23 crystallinity, 21 mechanical property, 8 and so forth.…”

Gas permeation and microstructure of reduced graphene oxide/polyethyleneimine multilayer films createdviarecast and layer-by-layer deposition processes

“…[44][45][46] Thus, gas permeation in polymer is a very complex phenomenon, and there is rarely a simple linear relation between the gas permeability and a given parameter. [44][45][46]90 We found that there is no linear relation between the free volumes and the gas permeability for the PEI/RGO composite lms. Nevertheless, the PALS results strongly suggest that the decrease in free volume size has made a signicant contribution to the excellent gas barrier property of the PEI/RGO composite lms.…”