LAUSR

The development of degradable polymeric materials such as degradable polyurethane or polyurea has been much highlighted for resource conservation and environmental protection. Herein, we demonstrate a facile strategy of constructing mechanically strong and tough poly(urea-urethane) (PUU) thermosets that can be degraded under mild condition by using triple boron-urethane bonds (TBUB) as cross-linkers. By tailoring the molecular weight of the soft segment of the prepolymers, the mechanical performance can be finely controlled. Based on the cross-linking of TBUB units and hydrogen-binding interactions between TBUB linkages, the as-prepared PUU thermosets have excellent mechanical strength of ∼40.2 MPa and toughness of ∼304.9 MJ/m3 . Typically, the PBUU900 strip can lift a barbell with 60 000 times of its own weight, showing excellent load bearing capacity. Meanwhile, owing to the covalent cross-linking of TBUB units, all the PUU thermosets show the initial decomposition temperatures over 290 °C, which are comparable to those of the traditional thermosets. Moreover, the TBUB cross-linked PUU thermosets can be easily degraded in mild acid solution. The small pieces of PBUU sample can be fully decomposed in 1 M HCl/THF solution for 3.5 h at room temperature. This article is protected by copyright. All rights reserved.