Polymers based on divalent metal salts of p-aminobenzoic acid: a review

Divalent metal salts of p-aminobenzoic acid are useful starting materials for syntheses of ionic polymers into which metal is firmly incorporated. This paper is a review of a series of polymers that have been prepared using the metal salts. The salts can react with compounds having functional groups capable of reacting with amino groups.

By polyaddition reactions of the salt–aromatic diamine with diisocyanate, and with isocynate-terminated adducts of diisocyanate and dialkylene glycol, halatotelechelic polyureas and polyurethane-ureas are obtained. By amine–epoxy reactions of systems of the salt–diamine–bisepoxide, and addition reactions of systems of the salt–dicarboxylic acid anhydride–bisepoxide, metal-containing cured resins are obtained. In this case, the metal carboxylate groups of the salts have catalytic activities for the curing reactions, and also for etherification of epoxy groups as a side reaction. Therefore, crosslinking of bisepoxide with the salts, and with adducts of the salts and the anhydride, has been investigated by taking advantage of the catalytic activity of the metal carboxylate groups for the etherification of epoxy groups. Interestingly, the metal-containing cured resins obtained by crosslinking by etherification of bisepoxide with the adducts show very high impact strength. © 1997 John Wiley & Sons, Ltd.