Tailoring vinylogous urethane chemistry for the cross-linked polybutadiene: Wide freedom design, multiple recycling methods, good shape memory behavior

Abstract

Vinylogous urethane chemistry can provide the sustainable way to address the demands for reprocessing the cross-linked polymers. In this paper, we extended this method to prepare the existing commercially available cross-linked polybutadiene (PB) with multiple reprocessing ways. We firstly attach acetoacetyl group to the chains of PB and then use diamines as cross-linkers to form vinylogous urethanes involved network, which could be tailored with great freedom, including via the content of attached acetoacetyl group, the ratio of amine to acetoacetyl group and different types of amine. Furthermore, the dynamic nature of the cross-linked PB is studied by stress relaxation. Based on the Arrhenius equation, the activation energy for chain re-arrangement is calculated about 48 ± 5 kJ mol−1 and the network could be efficiently reshuffled at the temperature between 120 °C and 150 °C. More important, the cross-linked PB could be effectively remolded by hot pressing or solvent assisted welding methods via catalyst-free transamination of vinylogous urethanes. We envisage that this strategy may provide an eco-environmental method to dispose the waste rubbers and prolong their life time.