Boronic-Ester-Based SBS Vitrimer with a Synergistic Zn2+-Coordinated Network Toward Mechanically Robust and Malleable Elastomers

The incorporation of dynamic covalent bonds (DCBs) has transformed thermoplastic elastomers into vitrimers. However, it still remains a challenge to solve the trade-off between mechanical properties and processability of vitrimer-like elastomers. In this work, poly(styrene–butadiene-styrene) (SBS) vitrimer with dual dynamic networks were prepared through thiol–ene click chemistry and reactive processing. By grafting 3-mercaptopropionic acid (MPA) onto SBS and subsequent cross-linking with zinc oxide and BDB, dynamic networks with zinc ion(Zn2+) coordination and dynamic boronic ester bonds were established. The structure and mechanical performance could be tailored by adjusting the ratio of the two networks. When increasing Zn2+ coordination bonds along with fixed BDB content, the gel content of SBS vitrimers varies from 30.62% to 69.54%. The dual-network sample demonstrated a synergistic effect with the highest elongation at break (526.41%) and a tensile strength of 13.40 MPa, outperforming single-network samples. All the SBS vitrimers show Arrhenius-type stress relaxation behavior, and the activation energy for dynamic bond exchange energy (Ea) of SBS with dual dynamic network was 76.69 kJ/mol. After three reprocessing cycles, the elastomer retained over 80% of its original mechanical properties. Therefore, this work offers a promising strategy for fabricating elastomers with excellent mechanical performance and recyclability, which is expected to have a significant impact on the design and preparation of high-performance elastomers.