Crosslinked reprocessable phosphor/polyurethane composite networks with thermal induced self-healing capacity and ultraviolet conducted fluorescence effect

In recent years, self-healing materials have attracted extensive attentions, however, the low elasticity have limited their applications, and it is difficult to track their healing process on macroscale. Herein covalently crosslinked polyurethane (PU) composite networks were developed with thermal induced self-healing capability and ultraviolet (UV) initiated fluorescence effect, which were synthesized by polytetrahydrofuran glycol (PTMG) as soft segment, hexamethylene diisocyanate (HDI) as hard segment, incorporating with blue phosphate (BP) of SrAl2O4 doped with Eu2+, Dy3+. The physio chemical properties and self-healing process of polyurethane were studied by differential scanning calorimetry (DSC), X-ray diffraction (XRD), atomic force microscope (AFM), optical microscope (OM), dynamic mechanical analysis (DMA) and tensile test. The results showed that the network materials were successfully developed with high elastic tensile properties. After healing at 60 °C for one hour, the PU network demonstrated a high healing efficiency and elongation at break. Moreover, the obtained hybrid networks emitted an intense blue light under UV with high fluorescent intensity to track healing process. Additionally, the synergistic effect of transesterification of dynamic hydrogen bond provided the composite networks reproducibility for recycling use. This self-healing polyester material shows promising applications in the fields of diagnostic healing and optoelectronic components.