Enhanced mechanoluminescence of ZnS:Mn2+ in flexible polyurethane via interfacial interactions

In this work, we extend the flexible matrix for the mechanoluminescent material of wurtzite ZnS:Mn2+ from conventional polydimethylsiloxane to polyurethane. The results from scanning electron microscopy images and stress-strain curves suggest that there are interfacial interactions between polyurethane chains and ZnS:Mn2+ particles, arousing a significant improvement on the elasticity modulus. The interactions are beneficial for the mechanical energy transfer from polyurethane chains to the embedded ZnS:Mn2+ particles, and thus achieving ca. 40 % improvement on the mechanoluminescence intensity compared to the ZnS:Mn2+/polydimethylsiloxane composite. The Fourier transform infrared spectroscopy results further identify that the interfacial interactions in ZnS:Mn2+/polyurethane should come from the formation of hydrogen bond between -NH- and ZnS:Mn2+, and therefore the enhanced mechanoluminescence mechanism of ZnS:Mn2+ in polyurethane is proposed. Because of the unique application scopes of polyurethane, the as-fabricated ZnS:Mn2+/polyurethane flexible composite shows promising applications in the fields of architectural structure, mechanical seal and aviation industry for mechanics visualizations.