Effect of Rosin Structure Position in Chain Segment on Properties of Self-Healing Polyurethane

The advancement of modern technology has driven the development of engineering polymer materials with integrated properties. However, achieving a combination of exceptional mechanical strength and toughness remains a significant challenge. In this paper, a kind of prospective polyurethane elastomer reinforced by high steric hindrance ring structure is reported. Using polytetramethylene ether glycol or rosin-based polytetramethylene ether glycol, a prepolymer was synthesized by adding isophorone diisocyanate, followed by the incorporation of 2,5-dithiobiurea or rosin-based diol as a chain extender, resulting in elastomers with a rosin skeleton in soft or hard segments through molecular engineering. Among them, the tensile strength and toughness of the elastomer with rosin skeleton located in the soft segment are 23.3 MPa and 132.6 MJ·m–3, respectively. The elastomer with rosin skeleton locate·d in the hard segment exhibits superior mechanical properties, with tensile strength and toughness of 31.5 MPa and 184 MJ·m–3, respectively. The reinforcing effect of the rosin skeleton, combined with its ability to increase the free volume of segments and promote their migration, achieves the combination of robust mechanical properties and high healing efficiency (>97%). The bulky rosin backbone effectively addresses the inherent trade-off between toughness and strength, offering a potential strategy for the future development of high-performance self-healing engineering materials.