Abstract: Disclosed is a method of treating a polyimide, comprising: providing a polyimide to be treated; and contacting the polyimide to be treated with a fluid to obtain a treated polyimide; wherein the polyimide comprises a first repeat unit derived from pyromellitic dianhydride (PMDA) and a second repeat unit derived from 4,4?-oxodianiline (4,4?-ODA); and wherein the fluid comprises a supercritical fluid, a liquid with a surface tension of 10.0 mN m?1 or less under the conditions of the contacting step, or a mixture thereof. Also disclosed are polyimides obtainable by the methods of the invention, formed polyimide products comprising the polyimides of the invention, and articles comprising the formed polyimide products of the invention.