GB2575532A — Porous, wet-triggered shrinkable materials

USPTO Abstract

A substrate includes a double-network polymer system including a cross-linked, covalently-bonded polymer and a reversible, partially ionicly-bonded polymer, wherein the substrate has a moisture level less than or equal to 15 percent of the total weight of the substrate, wherein the substrate is porous, and wherein the substrate includes a latent retractive force. A method for manufacturing a substrate includes producing a double-network hydrogel including a cross-linked, covalently-bonded polymer and a reversible, ionicly-bonded polymer; elongating by force the double-network hydrogel in at least one direction; treating the double-network hydrogel with an organic solvent with a volatile and water-miscible organic solvent to replace a majority of water within the double-network hydrogel; evaporating the organic solvent while the double-network hydrogel is still elongated to form a substantially-dried double-network polymer system; and releasing the force to produce the substrate.