Printable, Down/Up‐Conversion Triple‐Mode Fluorescence Responsive and Colorless Self‐Healing Elastomers with Superior Toughness

Abstract Expanding the practical application range of self‐healing materials has become an important challenge for developing smart materials. Herein, the synthesis of printable, triple‐mode fluorescence responsive, and colorless self‐healing elastomers, formed by the combination of disulfide cross‐linked polyurethane (PU) polymers, carbon dots (CDs) down‐conversion fluorescence materials, and lanthanide ions doped upconversion fluorescence materials. The PU elastomers with optimal mechanical properties and good restorability (recover large strain of 500% after relaxation at room temperature (R.T.) for 2 h) are selected to incorporate CDs for fabricating fluorescence responsive elastomers (denoted as PU‐CDs). Significantly, the prepared PU‐CDs exhibit not only superior tensile strength and toughness (20.95 MPa and 85.13MJ m –3 , respectively) than the previously reported R.T. self‐healing elastomers but also show good self‐healing properties and achieve blue fluorescence emissions under the ultraviolet excitation. Furthermore, a series of dual‐mode fluorescence patterns based on formulated core@shell structural upconversion inks are prepared on the transparent PU‐CDs elastomers by a directly screen‐printing method. Self‐healing and integrating a series of fluorescence patterns and damaged electrical patterns can also be accomplished successfully. The designed self‐healing materials provide new ideas and important guidance for developing and applying the next generation of smart materials.