Novel multiblock polyesterurethanes containing crystalline hard and amorphous soft segments and pendant cinnamamide moieties were designed and synthesized via a two-step polyaddition reaction using N,N-bis(2-hydroxyethyl) cinnamamide (BHECA), biodegradable poly(l,l-lactide) (PLLA), and poly(ε-caprolactone) (PCL) diols as raw materials and hexamethylene diisocyanate (HDI) as coupling agent and characterized by (1)H NMR, FTIR, UV, DSC, tensile and photomechanical tests, and so on. The copolymers behaved as typical thermoplastic elastomers and showed satisfactory thermal and mechanical properties. They also exhibited light-induced shape memory effect (LSME) at room temperature on exposure to light stimuli. The pendant cinnamamide groups work as photoresponsive molecular switches and provide the polymer with LSME via reversible [2 + 2] cycloaddition cross-linking. The strain fixity (R(f)) increases with the content of BHECA and the strain recovery (R(r)) increases with the content of PLLA. The R(f) reaches 50% at a BHECA content of 20 wt % and the R(r) reaches >95% at PLLA content of 50 wt %.

Compared to ultraviolet light, visible light as an excitation light source has lower phototoxicity and deeper penetrability. This is of importance to explore the application of long afterglow materials with visible light as the excitation wavelength. In this work, multicolor long afterglow materials excited by visible light were prepared by embedding carbon dots (CDs) in boron oxide (B 2 O 3 ) and the formation of carbon−boron bonds, and the glassy state of B 2 O 3 during the heating process protected the triplet excitons from being quenched, thereby promoting the emission of long afterglow. In addition, some CDs/ B 2 O 3 composites show dual-mode afterglow emission with thermally activated delayed fluorescence (TADF) and roomtemperature phosphorescence (RTP) at the same time. These as-designed multicolor CDs/B 2 O 3 composites exhibit a long lifetime of 445.9 ms, a high afterglow quantum efficiency of 17.61%, and high stability. Meanwhile, the afterglow can be observed at room temperature by the naked eye and lasts for several seconds when the visible light is just switched off. These as-obtained CDs/B 2 O 3 composites with visible-light-excited multicolor long afterglow emission have shown potential in reversible ratiometric temperature sensing, latent fingerprint identification, information anticounterfeiting, and encryption.

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