Self-Healable, Stretchable, and Super-Soft Bottlebrush Polyester Elastomers for Sensitive Flexible Sensors

While much effort has been devoted to the creation of super-soft elastomers, there is a dearth of research aimed at self healable and super-soft renewable elastomers. Herein, self-healing and super-soft renewable elastomers are developed based on bottlebrush architecture design and dynamic associative transesterification. The bottlebrush polymer precursors are generated by ring-opening metathesis polymerization (ROMP) of the norbornene-terminated macromonomer poly(epsilon-caprolactone-co-L-lactide) (PCLLA) (NB-PCLLA). After introducing alkyne groups onto the end of PCLLA side chains, the bottlebrush polymers are cross linked to achieve elastomer networks via a UV-induced "click" thiol-yne reaction between the terminal alkyne groups and the dithiothreitol (DTT) additive. The resulting materials exhibit a shear modulus as low as 17 kPa, high stretchability with breaking strains as large as 315%, and a self-healing efficiency of 95.6% at an elevated temperature of 80 degrees C. Taking the super-softness advantage, flexible sensor devices are assembled based on the prepared elastomer, which are highly sensitive to deformation with a gauge factor of 0.347. This work demonstrates that high-performance biodegradable materials with unique properties that conventional linear polymers impossibly possess can be easily constructed by molecular architecture design using bottlebrush polymers as building blocks.