Mechanically Robust\nand Chemically Recyclable Poly(β-Amino\nEsters)-Based Thermosetting Plastics

The development of chemically recyclable thermosetting\nplastics\nusing dynamic covalent bonds is of great importance in the construction\nof a sustainable society. However, there remains a bottleneck barrier\nin fabricating dynamic covalent thermosetting plastics with simultaneously\nhigh mechanical strength, thermal and dimensional stability, and room-temperature\nchemical recyclability. Herein, a series of poly(β-amino esters)\n(PBAEs)-based thermosetting plastics with high mechanical strength,\ndesirable dimensional stability, and room-temperature chemical recyclability\nwere fabricated through the aza-Michael addition reaction of bisphenol\nA glycerolate diacrylate (BG), poly(propylene glycol) bis(2-aminopropyl\nether) (PPG), and adipic acid dihydrazide (ADH). By increasing the\nmolar ratios of ADH, the mechanical properties of PBAE-based thermosetting\nplastics can be scientifically enhanced via the increase of the cross-linking\ndensities and hydrogen bond contents in the polymer networks. Typically,\nthe tensile strength and Young’s modulus of PBAE<sub>5</sub> can be improved to 4.5 and 10.6 times of PBAE<sub>1</sub>, respectively.\nMeanwhile, based on the rigid polymer network structures, PBAE-based\nthermosetting plastics exhibited very small creep strain at evaluated\ntemperatures. More importantly, PBAEs-based thermosetting plastics\ncan be easily depolymerized into value-added monomers in an alkaline\naqueous solution at room temperature through the hydrolysis of β-amino\nesters. Therefore, systematically tailoring the cross-linking density\nand hydrogen bond contents of the polymer network is an efficient\nand feasible strategy to construct mechanically strong and dimensional\nstable dynamic covalent thermosetting plastics with room-temperature\nchemical recyclability.