Polymer-Stretching-Regulated Microscopic Photoluminescence of Vibration-Induced Emission (VIE) Molecules

Photoluminescence materials play an inseparable role in the application of polymer systems. However, intrinsic polymer systems have rarely been intuitively interpreted based on photoluminescence regulation. A novel photoluminescence mechanism called vibration-induced emission (VIE) has recently drawn great attention due to its multicolor fluorescence from a single molecular entity. Based on the unique fluorescent properties of VIE molecules, we doped 9,14-diphenyl-9,14-dihydrodibenzo[a,c]-phenazine (DPAC) and its derivative DPAC-CN in two stretchable polymers, poly(ε-caprolactone) and ethylene vinyl acetate (EVA) copolymer, to explore the important relationship between luminophores and polymer systems. This research focused on the multicolor photoluminescence of the obtained blend films that resulted from stretching exertions and temperature responses. The successive conformational alterations of VIE molecules endowed continuous photoluminescent changes. Meanwhile, the multicolor variations also provided specific visual evidence regarding the amplified tensile stresses and microstructural changes in the polymer. This demonstration will therefore provide advantageous insights into the development of functional optical materials.