Self-healing Polyurethane Elastomer Based on Molecular Design: Combination of Reversible Hydrogen Bonds and High Segment Mobility

Polyurethane (PU) belongs to a class of special polymeric materials with hydrogen bonds, which has the potential for self-healing ability. In the present work, by introducing polypropylene glycol (PPG) blocks with high segment mobility and different block lengths on the ends of PU chains, the PUs with adjustable self-healing ability were successfully obtained. The self-healing ability of the PUs firstly increases with the increase of the PPG block lengths, but then decreases. This phenomenon can be attributed to the combined effects of the density of hydrogen bonds and the mobility of PPG segments. At first, the increase of the PPG block length leads to the improvement of mobility of PU chains, which is beneficial for the enhancement of the self-healing. However, the further increase of the PPG block length results in the reduction in the hydrogen bond density, finally leading to the decrease of the self-healing ability of the PUs.