| abstract |
Disclosed is a polyimide ammonium salt comprising the reaction product of an ethylenically unsaturated amine with an aromatic polyimide having pendant carboxylic acid groups, said polyimide comprising the reaction product of diamine and aromatic dianhydride, where the diamine comprises an aromatic carboxylic acid diamine having at least one carboxylic acid. A substrate can be coated with the polyimide ammonium salt by forming a composition of a crosslinking agent and a solution of the polyimide salt in an organic solvent, spreading the composition on the substrate, evaporating the solvent to form a coating, exposing at least some of the coating to actinic radiation to crosslink and insolubilize the exposed portions of the coating, and washing the unexposed portions away by dissolving them in an organic solvent. |