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

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.