To provide a method of producing a water-soluble or wetable, mixed amide/imide polyamino acids such as copolymers of aspartate and succinimide, related imide-containing polyamino acids, polysuccinimide or derivatives thereof.

Disclosed is the method of synthesis of copoly (succinimide-aspartate) copolymers and derivatives thereof, in the presence of an end-capping initiator, prepared in a thermal, a supercritical fluid, in the molten phase or in the solid phase. Also disclosed is the method of isolating, compounding and processing the copoly (succinimide-aspartate) and its derivatives.