POROUS MATERIALS, WHICH SHRINK WHEN EXPOSED TO MOISTURE Russian patent published in 2020 - IPC C08J3/75 A61L15/60 C08L33/26 C08L5/04 C08J9/28 

FIELD: technological processes.

SUBSTANCE: invention relates to a substrate which comprises a polymer system with a double network, comprising a crosslinked covalently bonded polymer and a reversible cross-linked polymer, partially bonded by ionic bonds, wherein the substrate is characterized by moisture content equal to 15 percent or less of the total weight of the substrate, the substrate is also porous and provides a concealed tightening force. Invention also relates to a method of making a substrate, comprising obtaining a double-layer hydrogel, comprising a crosslinked covalently bound polymer and a reversible cross-linked polymer bonded by ion bonds; elongation of hydrogel with double net under action of force in at least one direction; treatment of hydrogel with double network with the help of organic solvent, with the help of volatile and water-miscible organic solvent, with displacement of most part of water from hydrogel with double network; evaporation of organic solvent, while hydrogel with double network is still elongated, to form practically dried system based on polymer with double network; and releasing force to obtain substrate.

EFFECT: porous materials based on hydrogel with double network under the invention provide fast shrinkage in one direction and expand in other direction at action of liquid.

20 cl, 2 dwg