Bio-based, healable, and recyclable polyurethane materials conform to the sustainability of the polyurethane industry. By introducing dynamic covalent bonds, the cross-linked polyurethane can obtain the performance of network rearrangement, thereby realizing self-healing and reprocessing. In this work, a self-healing/renewable polyurethane based on bio-based vanillin and tyrosine was successfully synthesized solvent-freely and catalysts-freely. Due to two different thermal reversible mechanisms, metathesis of imines and deblocking/re-blocking of phenolic urethanes, the obtained PU has considerable self-healing efficiency and renewability. At 120 °C, the surface scratches almost completely disappear within 90 min, and the tensile strength can be restored to ∼ 95% within 2 h. After remolded for 5 times, the chemical structure, glass transition temperature, deblocking behavior, tensile strength, elongation at break and gel content didn’t change significantly. Both the environmental friendliness of bio-based raw materials and the renewability of the obtained polyurethane materials meet the requirements of sustainability.
Jingjing Qin,Liyan Liang,Xiaohong Liu,Jiaming Liu,Dingsong Wang,Min Shi,Chaolong Yang
In this paper, a series of small monomers were synthesized to explore the dynamic reversible properties of phenol-carbamate bonds (PCBs), and the bimolecular exchange mechanism of PCBs was verified. Based on this mechanism, a novel thermo-healing recyclable epoxy resin with high mechanical performance and shape memory function was successfully developed. Meanwhile, the number of reversible phenol-carbamate bonds in this system was increased by molecular structure design, which increased the chance of reversible cleavage and recombination of the dynamic covalent bonds . Compared with our previous work, the thermo-healing efficiency of the epoxy thermosets was greatly increased, and the target polymer achieved an excellent balance between high thermo-healing efficiency and good mechanical performance. Further post-treatment experiments show that the cured epoxy resin can also be well recycled by solvent degradation or hot-pressing process. What's more, a novel carbon fiber (CF) reinforced polymer composite material was synthesized by taking that prepared epoxy thermoset as a matrix, which greatly improve the mechanical properties of epoxy resin, and the CF cloths can be recycled when the epoxy resin is removed by chemical degradation . In addition, due to the existence of reversible crystallizable switching segments in the epoxy resin system, when the temperature is above its T g , it can be triggered by thermal energy, so that the film can rapidly recover from the temporary shape to the permanent shape. This study also provides a new direction for the development of novel multifunctional intelligent polymers.
危险品化学品经营许可证（带存储）