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

The subnano level free‐volume hole features of poly(styrene sulfonic acid) (PSSA) grafted poly(ethylene‐co‐tetrafluoroethylene) polymer electrolyte membranes (ETFE‐PEMs) are investigated using positron annihilation lifetime spectroscopy (PALS). The hole sizes are formed mainly at the graft‐polymeriz...

Full description

Saved in:
Bibliographic Details
Published in:Polymers for advanced technologies 2022-09, Vol.33 (9), p.2952-2965
Main Authors: Tap, Tran Duy, Long, Tran Hoang, Hieu, Dinh Tran Trong, Hao, Lam Hoang, Phuong, Huynh Truc, Luan, Le Quang, Van Man, Tran
Format: Article
Language:English
Subjects:
Electrolytes
Ethylene tetrafluoroethylenes
free volume hole
fuel cell
Fuel cells
Grafting
Hydrogen fuels
Membranes
Polymers
Polystyrene resins
Positron annihilation
positron annihilation lifetime spectroscopy
Positronium
radiation‐induced grafting
Sulfonic acid
Tensile strength
Citations: Items that this one cites
Items that cite this one
Online Access:Get full text
Tags: Add Tag
No Tags, Be the first to tag this record!
Description
Summary:The subnano level free‐volume hole features of poly(styrene sulfonic acid) (PSSA) grafted poly(ethylene‐co‐tetrafluoroethylene) polymer electrolyte membranes (ETFE‐PEMs) are investigated using positron annihilation lifetime spectroscopy (PALS). The hole sizes are formed mainly at the graft‐polymerization step and are not altered dramatically at the sulfonation. With increasing grafting degree, τ4, standing for the annihilation of ortho‐positronium (o‐Ps) in the larger free‐volume holes of the mobile amorphous layers and the PSSA grafts outside of the lamellae, decreases monotonously, whereas τ3, representing for that in the smaller free‐volume holes of the lamellar amorphous regions, the PSSA grafts, and the interface zones inside the lamellae, only shows a slight decrease. From the viewpoint of free‐volume hole sizes, gas molecules are predicted to pass dominantly through the mobile amorphous phases and the PSSA grafts outside of the lamellae. Specifically, the limited hole concentration induced by confining lamellae at the interfacial zones is observed. Thus, the obtained results are associated with a significant reduction of gas passing and the moderate or higher tensile strength for the ETFE‐PEMs in comparison to Nafion‐212.
ISSN:1042-7147
1099-1581
DOI:10.1002/pat.5761