Self-healing polyurethane (pu) material, double-layer self-healing pu film, and preparation method and use thereof

A double-layer self-healing polyurethane (PU) film, comprising

• a soft-layer PU film arranged on a surface of a matrix;
• and
• a hard-layer PU film arranged on a surface of the soft-layer PU film,
• wherein the soft-layer PU film is prepared from a PU material I of a self-healing PU material;
• and the hard-layer PU film is prepared from a PU material II of the self-healing PU material;
• the PU material I is prepared from raw materials comprising a polyol substrate I, a diisocyanate I, a tin-based catalyst I, a T-type chain extender, and a chain extender I at a molar ratio of (10-20):(20-40):(1-3):(2-8):(8-12);
• the PU material II is prepared from raw materials comprising a polyol substrate II, a diisocyanate II, a tin-based catalyst II, the T-type chain extender, a metal salt, and a chain extender II at a molar ratio of (10-20):(20-40):(1-3):(5-10):(2.5-10):(5-10);
• a metal ion in the metal salt being one or more selected from the group consisting of Zn2+, Cu2+, and Fe3+;
• the polyol substrate I and the polyol substrate II each are independently selected from the group consisting of a polyester polyol and a polyether polyol;
• and
• the T-type chain extender has a structure represented by formula A: