Iron ion cluster-OH coordination as high-efficiency sacrificial bond for reinforcement of elastomer

Although hydroxy is an easily-available group for polymer functionalization and can serve as a ligand to coordinate with metal ions, the hydroxy-ion cluster coordination remains unexploited as sacrificial bond to reinforce elastomers. This work reports a very strong rubber by introducing iron ion cluster-OH coordination into a covalently-crosslinked rubber. With the introduction of 4.2 wt% Fe³⁺, the rubber exhibits a 6-fold increase in tensile strength and an 8-fold increase in modulus when compared with neat rubber. The achieved tensile strength (~20.9 MPa) and modulus (~12.7 MPa) are competitive to the highly-filled engineering rubbers. Overall, this work presents a new method to prepare high performance elastomers based on a hydroxylated polymer. As hydroxylated polymers can be readily prepared with commercially available polymers, the present study should promote comprehensive research and industrial applications of sacrificial bond strategy.