Speed-Induced Extensibility Elastomers with Good Resilience and High Toughness

The relationship between elongation at break of a material and stretching speed has always been known to be an inversed one. In this work, however, thermoplastic elastomers based on two thermodynamically immiscible components, poly(dimethylsiloxane) (PDMS) and poly(propylene glycol) (PPG), exhibit speed-induced extensibility (SIE). This leads to significant enhancement in Young's modulus, strength, and elongation at break with increased stretching speed. As such, the system is capable of achieving elongation at break of more than 9000% at a 70 min–1 stretching speed and excellent notch resistance such that the strain and the fracture energy of the notched specimen can reach up to ∼2000% and ∼53,600 J/m2, respectively, surpassing the most reported PDMS-based elastomers. The toughness is also enhanced by 6.4 times merely by increasing the stretching speeds from 2 to 70 min–1. In addition, the microphase re-separation of PDMS and PPG, together with entropy elasticity of polymer chains, endows the elastomer with a good elastic recovery of ∼98%. Last, the incorporation of a reversible hydrogen bond also allows the elastomers with autonomous self-healing ability (efficiency ∼ 95%). This work opens up the possibility for developing highly stretchable and resilient materials, which can be applied in areas such as artificial muscles.