Condensation polymers are prepared by agitating a mixture comprising glyoxal, a monomer comprising two or three primary aromatic amine groups, an organic solvent, and water at a temperature between 20° C. and 100° C. The resulting solution can be applied to a surface of a substrate, forming an initial film. Curing the initial film layer using two or more heating steps, wherein one of the heat steps is performed at a temperature of 150° C. to 250° C., produces a cured film layer. Depending on the relative amounts of glyoxal and monomer used, the film layer can contain predominantly high Tg imine-containing units or predominantly lower Tg aminal-containing units. All film layers were highly resistant to the solvent used to prepare the polymer. The Tg of the polymer can be about 190° C. to greater than 300° C.