Dynamic/Static Hybrid Network Enabling Elastomeric Vitrimers with Accelerated Network Relaxation and Superior Creep Resistance

For vitrimeric systems, the undesired exchange of dynamic covalent bonds generally leads to a considerable creep deformation of the network. Although introducing static junctions is a feasible solution, it still suffers from a trade-off dilemma between reprocessability and creep resistance of the system. Herein, a multiphase design based on dynamic/static hybrid networks is outlined by incorporating highly cross-linked rubber granules encapsulated with static junctions far exceeding the percolation threshold into the rubber matrix, followed by cross-linking with dynamic boronic ester-containing cross-linkers. Under external loading, these rubber granules can store the mechanical energy within the network segments upon elastic deformation and spatially hinder the plastic flow of the matrix chains, enabling a system with superior creep resistance at moderate temperatures. Moreover, the elastic potential energy stored within the hard rubber granules can also transfer back to the soft matrix through strong interfacial adhesion, which induces an interfacial stress amplification effect to accelerate the bond exchange in adjacent regions and consequently improves the reprocessability. This strategy offers a feasible methodology to address the trade-off between reprocessability and creep resistance in conventional vitrimers, which is of great importance for promoting their practical applications in load-bearing or temperature-related applicaitons.