Premium
Polyphosphazene membranes. IV. Polymer morphology and proton conductivity in sulfonated poly[bis(3‐methylphenoxy)phosphazene] films
Author(s) -
Tang Hao,
Pintauro Peter N.
Publication year - 2000
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/1097-4628(20010103)79:1<49::aid-app60>3.0.co;2-j
Subject(s) - phosphazene , materials science , conductivity , ionic conductivity , polymer , polyphosphazene , polymer chemistry , membrane , activation energy , arrhenius equation , chemical engineering , composite material , chemistry , biochemistry , engineering , electrode , electrolyte
The microstructure of sulfonated poly[bis(3‐methylphenoxy)phosphazene] was studied using wide‐ and small‐angle X‐ray diffraction. A reflection peak, attributed to the presence of ionic clusters, was observed in the small‐angle X‐ray diffraction patterns of hydrated and dry polymers with an ion‐exchange capacity (IEC) ≥0.6 mmol/g. The Bragg spacing from the ionic cluster structure was about 30 Å for the nonhydrated polymer and 50 to 90 Å for fully hydrated films. The effects of IEC, cation form of the polymer, temperature, and polymer water content on the cluster structure were investigated. The specific proton conductivity of water‐swollen, sulfonated poly[bis(3‐methylphenoxy)phosphazene] films at 25°C increased with increasing IEC, with a maximum conductivity of 0.1 S/cm at a polymer ion‐exchange capacity of 1.6 mmol/g. The water‐content percolation threshold for conductivity was between 17.5 and 25 vol %, and decreased with polymer IEC. The temperature dependence of proton conductivity for 1.2 mmol/g IEC poly[bis(3‐methylphenoxy)phosphazene] membranes exhibited Arrhenius behavior with an apparent activation energy of 27.8 and 36.7 kJ/mol for crosslinked and noncrosslinked polymers, respectively. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 79: 49–59, 2001