Extrudable Vitrimeric Rubbers Enabled via Heterogeneous Network Design

The state-of-the-art reprocessing of vitrimers still struggles in crude hot-compression processes. The highly cross-linked nature and glass-like viscoelastic behavior of vitrimers critically restrict the network chain mobility, which limits the application of continuous processing techniques during reprocessing. Herein, a multiphase design strategy is outlined through incorporating highly cross-linked vitrimeric powders into a polymer matrix, followed by cross-linking with dynamic covalent bonds (DCBs) containing cross-linkers to form multiphase DCB-based networks. Accordingly, inhomogeneous stress distribution can be achieved inside the networks during deforming. The resulting high interfacial stress significantly accelerates the network relaxation upon mechanical activation enabling extrudable reprocessability to the vitrimeric rubbers with ∼100% recovery of overall performance. Moreover, the inhomogeneous stress distribution also promotes the chain orientation of the networks, leading to a remarkably mechanical reinforcement of the samples without compromising the elasticity. We envisage that this design concept can indeed facilitate the vitrimers toward industrial applications, which is significant to the sustainable development of rubber industry.