Strain-Responsive Persistent Room-Temperature Phosphorescence from Halogen-Free Polymers for Early Damage Reporting through Phosphorescence Lifetime and Image Analysis

Mechanically responsive materials (MRMs) usually showing observable changes in emission intensity (mechanochromic) under force stimuli have garnered increasing interest due to their broad range of potential applications. Relative to usual mechanochromic materials, a kind of alternative MRMs with changeable lifetime upon force stimuli in terms of mechanodecay is proposed. A catalog of novel MRMs with both mechanochromic and mechanodecay characteristics is reported. Halogen-free semicrystalline polymers doped with chromophores showing bright and ultralong room-temperature phosphorescence (RTP) under ambient conditions are facilely fabricated through melt blending approaches. Upon being stretched or compressed, the RTP polymers show abundant changes in fluorescence intensity, emission color, RTP intensity, and RTP lifetime. Such RTP polymers with multiple strain-responsive visual signals offer a kind of new MRMs useful for visually sensing the deformation of materials. Leveraging remarkable change in RTP lifetime under force stimuli, deformation process of polymers is investigated through phosphorescence lifetime and image analysis. Early damage warning for engineering polymers is achieved. Given the merits of high sensitivity, multiple visual signals, low cost, and simple operation, such RTP polymers provide a class of new MRMs useful for deformation sensing and early damage reporting of engineering materials.

Automated summary

This study reports a new type of mechanically responsive materials, RTP polymers, which possess both mechanochromic and mechanodecay characteristics. These polymers exhibit abundant changes in fluorescence intensity, emission color, RTP intensity, and RTP lifetime under force stimuli, enabling the detection of material deformation. Through phosphorescence lifetime and image analysis, early damage warning for engineering polymers can be achieved.