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.