Asymmetric dynamic strategy for high-strength self-healing polyurethane and its superhydrophobic composite materials

Developing elastomers with both high mechanical strength and reparability remains a formidable challenge. In this work, asymmetric six-membered ring structures and long side chain structures were introduced into the molecular main chain and side chain, respectively. This caused the hard domains within the molecular chain to be loosely packed, forming asymmetric dynamic hard domain structures. At the same time, multi-level asymmetric hydrogen bond structures were formed between molecules. The structure and properties of the materials were characterized and tested using infrared spectroscopy, mechanical property testing, dynamic mechanical analysis, and contact angle measurement. The experimental results showed that the resulting polyurethane elastomer exhibited strong tensile strength, reaching up to 54.4 MPa, excellent elongation at break (648 %), and good self-healing efficiency (87.8 %). Additionally, using interfacial composite technology, hydrophobically modified TiO2 nanoparticles were compounded with polyurethane to prepare a super-hydrophobic surface coating with a contact angle of up to 160 degrees. This coating demonstrated excellent acid and alkali resistance, wear resistance, and water droplet impact resistance. The multifunctional composite materials prepared in this study have broad potential applications in the fields of coatings and flexible hydrophobic films.