New Advances in Polyurethane Materials for Ultra-Fast Repair

The development of polymer materials with self-healing ability, so that damaged materials can effectively self-heal and regenerate, is one of the means to alleviate "white pollution". However, it is difficult to realize room temperature self-repair of glassy polymers because of the high density of molecular stacking and the frozen network of molecular chain movement. Although breakthroughs have been made in the glassy self-healing polymer materials in recent years, the low mechanical properties, complex repair methods and long repair time make it difficult to be practically applied. Therefore, the development of high-performance polymer materials capable of rapid repair in the glassy state is undoubtedly a major challenge.

Recently, Prof. Jinrong Wu's team at the College reported a glassy hyperbranched polyurethane (UGPU) that can be repaired rapidly at room temperature. In this work, the researchers obtained polyurethane materials with acyclic heteroatomic chains and hyperbranched structures by reacting with the coupled monomer method. This unique molecular structure combines the high molecular motility of hyperbranched polymers with the multiple hydrogen bonds of polyurethanes to form a high-density hydrogen bonding network based on urea bonds, urethane bonds, and branched terminal hydroxyl groups.UGPU has a tensile strength of up to 70 MPa, a storage modulus of 2.5 GPa, and a glass transition temperature that is much higher than the room temperature (53 ℃), which makes UGPU a rigid transparent glassy plastic.

UGPU has excellent self-healing ability, and it can realize glassy self-healing under pressure. At the same time, the researchers found that extremely small amounts of water applied to the UGPU section significantly accelerated the repair rate. It's an all-time record for self-healing materials. Moreover, the repaired sample can resist a creep test of 10 MPa, which is sufficient to meet the application requirements of rapid repair and continued service after damage to structural components.