Fig. 1. (Color online) (a) ATR-FTIR and (b) UV spectra of neat PAA, PAA & PDMS and PAA-PDMS materials.

Fig. 2. (Color online) Physical properties of PAA-PDMS elastomers. (a) Photographic image of the transparent PAA-PDMS elastomer film. (b) Photographic images of PAA-PDMS films under stretching, bending, and twisting. (c) Typical tensile stress-strain curves of films with various weight ratios between PAA and PDMS-OH (F-1-1, F-2-1, F-3-1, F-5-1, and F-10-1). (d) and (e) Tensile stress-strain curves of PAA-PDMS films within 40% strain under loading-unloading cycle. (f) Tensile stress between PAA-PDMS elastomer and skin. Insert photo shows adhesion strength test of the PAA-PDMS elastomer on skin.

Fig. 3. (Color online) Self-healing properties of PAA-PDMS elastomers. (a) Photographic images of self-healing process of F-3-1 film, the healed film is mechanically stable under stretching. Typical tensile stress-strain curves for (b) F-2-1, (c) F-3-1 and (d) F-5-1 film during three cutting-healing cycles. (e) Self-healing efficiencies of PAA-PDMS elastomer films of F-2-1, F-3-1, and F-5-1 during three cutting-healing cycles.

Fig. 4. (Color online) OM and SEM images of healed PAA-PDMS elastomer. (a) OM images of the self-healing process of F-3-1 without any external stimulus. (b) SEM images of the self-healing process (surface cut) of F-3-1 under vapor treating, the process is finished in ~3 min.

Fig. 5. (Color online) Schematic illustrations of the self-healing process of PAA-PDMS elastomers.

Fig. 6. (Color online) The fabrication, electrical and mechanical properties of PAA-PDMS/PEI-rGO sensors. (a) Schematic illustration of preparing PAA-PDMS/PEI-rGO sensors. (b) Variations of tensile performance of the PAA-PDMS/PEI-rGO sensor vs. applied strain. (c) The response of the self-healing strain sensors under various applied tensile strains after 500 stretching/releasing cycles under 3% applied strain.

Fig. 7. (Color online) Application of PAA-PDMS/PEI-rGO strain sensors: the corresponding response to the (a–c) wrist and (d–f) press of the pristine, surface cut healed and complete cut healed strain sensors.

Table 1. Mechanical properties of elastomer with different ratios of PAA and PDMS-OH.