Anionic ring-opening polymerization of several N-substituted diphenimides

Five N‐substituted diphenimides were prepared from the corresponding N‐substituted amic acids. Attempts to polymerize the prepared seven‐membered ring imides were partially successful. N‐phenyldiphenimide was relatively the best monomer that polymerized anionically using n‐butyl lithium or sodium metal as the initiater. The other N‐substituted imides were sluggish in anionic polymerization. The resistance of the seven‐membered ring imides toward ring‐opening polymerization was attributed to the stability of the rings caused by the two phenylene groups adjacent to the carbonyls. © 1993 John Wiley & Sons, Inc.