Positron Annihilation Lifetime Study of Graft-Type Fluorinated Polymer Electrolyte Membranes
Positron annihilation lifetime spectroscopy (PALS) measurements were performed on polymer electrolyte membranes (PEMs) synthesized by radiation-induced graft polymerization of styrene into crosslinked-polytetrafluoroethylene (cPTFE) films and subsequent sulfonation. The base cPTFE and polystyrene grafted films were also measured as references. The cPTFE based PEM was found to have free-volume holes with different radius of 0.28-0.30 nm and 0.44-0.45 nm. The larger holes may be located in PTFE amorphous regions, while the smaller ones are considered to exist in both PTFE crystallites and poly(styrene sulfonic acid) grafts containing no water.
S. J. Wang, Z. Q. Chen, B. Wang and Y. C. Jean
S. Sawada et al., "Positron Annihilation Lifetime Study of Graft-Type Fluorinated Polymer Electrolyte Membranes", Materials Science Forum, Vol. 607, pp. 70-72, 2009