Method for the preparation of hydrophilic spongy gels

摘要

A method for the preparation of a hydrophilic acrylonitrile-containing polymer comprising admixing a solution of said polymer in 47% to 75%, preferably 50 to 72% concentrated HNO3, with solid particles of a substance insoluble in said acid solution and soluble in water, aqueous solutions of said substance being operative to precipitate said polymer from said HNO3, shaping the mixture of the dissolved polymer with said solid substance to a desired physical shape, coagulating said shaped polymer in an aqueous medium and washing said solid particles out from the coagulated polymer, and articles made therefrom.