(37d) Triboluminescent Composites for Engineering Applications

Triboluminescence (TL) is a phenomenon/process that materials could emit light under mechanical stimuli, e.g., impact, rub, stretch, compression, etc. The synthetic TL materials are usually in the form of powders, which could be further composited with various matrices for practical applications. In this presentation, we will introduce our recent work on the synthesis and performance regulation of TL composites as well their applications in engineering. We first introduced the green emitting TL material SrAl₂O₄: Eu²⁺, Dy³⁺ in epoxy/graphite solid lubricating materials, and prepared SrAl₂O₄: Eu²⁺, Dy³⁺/epoxy/graphite composites. Based on the optimization of the chemical compositions, TL was achieved in the SrAl₂O₄: Eu²⁺, Dy³⁺/epoxy/graphite composites, while the mechanical and tribological properties were maintained simultaneously. By further developing a bilayer structure of SrAl₂O₄: Eu²⁺, Dy³⁺/epoxy/graphite composites (top layer: epoxy/graphite; bottom layer: SrAl₂O₄: Eu²⁺, Dy³⁺/epoxy/graphite), the epoxy/graphite-based solid lubricating materials were endowed the function of early warning of lubrication failure based on TL, which is significant to avoid major accidents in industry induced by the wear out of solid lubricating materials. In addition to the failure early warning applications in solid lubricants, we also introduced the red emitting TL material Sr₃Al₂O₆: Eu³⁺ in flexible polydimethylsiloxane (PDMS). The as-fabricated Sr₃Al₂O₆: Eu³⁺/PDMS flexible composites could emit luminescence under the stimuli of either rubbing or stretching, while the luminescent color was readily manipulated by varying the synthesis atmosphere of Sr₃Al₂O₆: Eu³⁺. Based on the above characteristics, two types of intriguing flexible devices were fabricated, i.e., a dual-responsive anti-counterfeiting device and a comprehensive stretching/strain sensor capable of sensing both strain level and stretching states. The above flexible devices were fabricated based on the unique dynamic stress responsiveness of Sr₃Al₂O₆: Eu³⁺/PDMS composites, representing the state of art in their own fields. Particularly, the developed stretching/strain sensor breaks the limit of static strain sensing in present researches, showing broad applications in damage monitoring, intelligent artificial skin, and other related fields.