Self-Healing and Shape Memory Linear Polyurethane Based on Disulfide Linkages with Excellent Mechanical Property

Self-healing polymeric materials have attracted extensively interests due to the ability to heal the damage autonomously. The self-healing systems based on dynamic disulfide bonds have been the most promising due to the efficient healing capacity at a mild condition. However, it is still of great challenge for designing the polymer with excellent mechanical and self-healing property by a simple synthetic route. Herein, a novel series of self-healing linear polyurethanes with the disulfide linkage as the grafting point were developed. The synthetic polymers all exhibited excellent mechanical properties (breaking strength and elongation at break were as much as 31.91 MPa and 1156% for PU-A). Meanwhile, the effects of different ratios of soft/hard segments on the mechanical properties and healing efficiencies have been investigated by stress-strain tests. The results showed that with the increase of soft segments contents, the breaking strength and elongation at break of the polymer improved significantly, while the healing efficiency and Young's modulus showed a declining trend. The self-healing polyurethane can quickly restore its over 90% of mechanical property after healing at moderate temperature for 10 min. The cyclic tensile tests also showed the dissipated efficiencies and self-recovery abilities of the polymers. Finally, the recovery capability tests verified the shape memory effect in the polymers, which can replace an external force to accelerate the healing process.