Dynamic Crosslinked Phosphorescent Poly(vinyl alcohol)-Terpyridine Films with Enhanced Mechanical Properties and Tunable Shape Memory

Achieving versatile room temperature phosphorescence (RTP) materials, especially with tunable mechanical properties and shape memory is attractive and essential but rarely reported. Here, a strategy was reported to realize multi-functional RTP films with multicolor fluorescence, ultralong afterglow, adjustable mechanical properties, and shape memory through the synergistic dynamic interaction of lanthanide (Ln^III)-terpyridine coordination, borate ester bonds, and hydrogen bondings in a poly(vinyl alcohol) (PVA) matrix. By varying the amount of borax, the mechanical properties of the films could be finely controlled due to the change of crosslinking degree of dynamic borate ester bonds in PVA. The assembly and disassembly of borate ester bonds upon the trigger of borax and acid were applied as reversible linkage to achieve programmable shape memory behavior. In addition, the films displayed both fascinating multicolor fluorescence and ultralong afterglow characteristics due to the presence of Ln^III doping and confinement of terpyridine in PVA. This study provides a new avenue to impart modulable mechanical strength and shape memory to RTP materials.