3D-Printable Self-Healing Soft Materials in Response to Ambient Humidity and Temperature

Stimuli-responsive soft materials exhibit tunable properties in response to external stimuli like heat, light, humidity, or magnetic fields, making them attractive for various applications in smart electronics. Long-term durability and reliability are crucial for these applications, and bioinspired self-healing properties can be incorporated to ensure functionality. Here we have created a moisture-induced, self-healing smart material that exhibits reversible property changes in response to ambient humidity and temperature. This spontaneous smart response is attributed to the synergetic interactions between PPGurea, a polymer with urea linkages, and an ionic liquid, which readily conducts electricity. This material is soft, transparent, and conductive, readily self-healing when hydrated. Dehydration, on the other hand, transforms it into an opaque and less conductive state, while significantly increasing its stiffness, strength, and toughness. The humidity/temperature-responsive smart material holds great promise for 3D-printed optoelectronics and smart windows, adapting seamlessly to ambient changes.