| abstract |
The sulfonation of aromatic polyether sulfones in a controllable manner is possible by means of sulfur trioxide in concentrated sulfuric acid as solvent. By maintaining a sulfur trioxide content of less than 6 percent by weight, based on the solvent, and a reaction temperature of less than 30° C., side reactions and degradation reactions are to a large extent suppressed. The resultant products are suitable for preparation of membranes. |