Multifunctional waterborne polyurethane films: Amine-response, thermal-driven self-healing and recyclability

Currently, the preparation and application of functional waterborne polyurethane has become a research hotspot in the field of polyurethane. In the present work, Different weight ratios of diacetyl oxime and coumarin diol were used as the reactive filler with isophorone diisocyanate (IPDI) and Poly propylene glycol (PPG) to prepare superior amine-response, self-healing and recyclable waterborne polyurethane films (WPU-x). Dynamic mechanical analysis was carried out to identify the self-healing properties of WPU-x. It was revealed that the WPU-2 film show an excellent self-healing capability based on the combination of the mobility of the soft segment, dynamic reaction of oxime carbamate bond and hydrogen bonds, and the mechanical properties self-healing efficiency can reach 91.11% after self-healing at 90 °C for 7 h. UV testing and fluorescence imaging results shown that WPU-2 film exhibit a rapid and concentration-dependent response to dimethylamine (DMA), and it also shows varying degrees of response to other organic amines. The WPU-2 film could be readily applied in cold chain transportation of shrimp and fish for real-time and visual monitoring the freshness of seafoods. At the same time, the WPU-2 film could be recycled via hot-pressing and solution casting. Therefore, this strategy provides some insights for preparing multi-functional waterborne polyurethane.