Reprocessable Nitrile Rubber Enabled by Thermoreversible Alkoxyamine Cross-linked Networks

Covalently cross-linked rubber is indispensable in many fields, such as automotive tires, gaskets, and sports equipment. It is of great significance to endow rubber with an efficient recycling performance. Herein, a tetrafunctional nitroxide radical cross-linked agent (QT) was synthesized and introduced into nitrile rubber (NBR) to prepare thermoreversible nitrile rubber (QNBR) by conventional rubber processing technology without additional additives. The nitroxide radicals in QT have the ability to react with the unsaturated carbon–carbon double bonds in the molecular chain of NBR to generate thermoreversible alkoxyamine (C-ON) bonds, which can dissociate and reform at the corresponding temperature. The study indicates that the recyclability and mechanical properties of QNBR are excellent and can meet the needs of practical applications. Furthermore, with the addition of the carbon black, reinforced nitrile rubber composite (QcNBR) also has high mechanical strength (up to 23.79 ± 1.76 MPa) and reversible efficiency (up to 67%). This study demonstrates that constructing a thermoreversible alkoxyamine cross-linking network is an effective method for the sustainable application of rubber materials.