Fig. 4. Self-healing, water-processable, and adhesive properties of PAA/betaine elastomer.

a Self-healing process of the PAA/betaine elastomer was observed by the optical microscope. A scar autonomously healed after 12 h at RH 80%. The experiment was repeated three times independently with similar results. b Three individual PAA/betaine elastomer blocks healed together to withstand bending and stretching. The elastomers were colored blue and orange with methylene blue and semixylenol orange, respectively. c Tensile curves of the original elastomer and those after successive four self-healing cycles. d PAA/betaine elastomer can be dissolved in water in 80 min. e Tensile curves of the original and recasted PAA/betaine elastomer films at RH 60% indicating its water reprocessability. f, g Ninety-degree peeling curves and corresponding interfacial toughness of PAA/betaine elastomer with different substrates (peeling rate = 50 mm min⁻¹). Data are presented as mean values ± SD, n = 3 independent elastomers. h Schematic adhesion mechanisms.