| abstract |
A method is provided for obtaining crosslinked polymers, particularly fluorinated polymers having pendent sulfonic acid groups, by crosslinking through pendent groups which include a sulfonyl chloride group (—SO 2 Cl). The sulfonyl chloride group may be removed by application of electromagnetic radiation, typically in the ultraviolet band, or a radical initiator, leaving behind a radical which readily binds covalently to other polymer strands or to crosslinking agents to form crosslinks. Typically, the polymer is made by providing a polymer comprising pendent groups which include a group according to the formula —SO 2 F and converting at least a portion of the —SO 2 F groups to —SO 2 Cl. After crosslinking, the remaining —SO 2 F groups may be converted to sulfonic acid groups, yielding a crosslinked polymer electrolyte. Such crosslinked polymer electrolytes may be used to make polymer electrolyte membranes (PEM's) that may be used in electrolytic cells such as fuel cells. |