7: POLY(ARYLENE ETHER SULFONE)S 185
presence of groups, such as −−Cl,−−NH
2
,−−OH,
−−SH, etc. In fact, the active agent in the sulfonation
reaction is theSO
+
3
cation. The sulfonationof aromatic
compounds is a reversible reaction. Sulfonating agents
can be classified into three groups, namely [39]:
1. Electrophilic agents: sulfuric acid, chlorosul-
fonic acid, fluorosulfonic acid,
2. Nucleophilic agents: sulfites, hydrogen sulfites,
and sulfur dioxide, which react with halogen
derivatives and double bonds, and
3. Radically reacting agents: sulfuryl chloride,
mixtures of sulfur dioxide and chlorine.
The sulfonation of the monomers prior to conden-
sation or direct sulfonation of the polymer results
in hydrophilic materials. These materials are used in
membrane technology ...