Mechanically induced radical crosslinking strategies for material self-strengthening have been widely applied in soft robotics and impact protection. However, this mechanism predominantly relies on polymer chain scission to generate active radicals, necessitating large loads to initiate reactions. This often induces damage and fails to address low-energy, precise reinforcement needs. Here, we introduce a mechano-oxidative synergistic strategy by incorporating the mechanosensitive small molecule initiator triethylborane-4-methoxypyridine (TEB-MeOPy) into a block copolymer network. At only 0.15 MPa stress, mechanical force synergizes with ambient oxygen to convert TEB-MeOPy into active radicals that drive efficient, irreversible crosslinking in the solid-state polymer, giving rise to an increment in mechanical strength for elastomers. This enables self-reinforcement triggered by localized high stress fields, bypassing the need for global high stress activation. Moreover, predictions from our stress-crosslinking degree model match well with the system's dynamic evolution, enabling controlled self-strengthening of the elastomer. The material exhibits superior responses under multimodal loading, surmounting environmental dependencies in solid-state polymer and conventional high threshold constraints, offering fresh insights for mechanochemically driven next-generation intelligent soft materials.
Fan et al. (Tue,) studied this question.