Room‐Temperature Phosphorescent Tough Hydrogels Based on Ionically Crosslinked Nonaromatic Polymers

Abstract

AbstractOrganic photoluminescent materials exhibiting room‐temperature phosphorescence (RTP) have attracted widespread attention. However, most of them can emit phosphorescence only in the solid state, which strongly limits their applications. Herein, a type of phosphorescent hydrogel with excellent mechanical properties is prepared by immersing an as‐prepared poly(vinyl alcohol) (PVA) hydrogel in a poly(sodium maleate) solution and then in a CaCl2 solution, followed by drying under stretching at 90 °C and finally soaking it in deionized water until equilibrium swelling to produce poly(vinyl alcohol)/poly(calcium maleate)‐DS ( PVA/PMACa‐DS) hydrogels. Such hydrogels exhibit excellent mechanical properties, showing tensile strengths up to 15 MPa, due to the presence of strong hydrogen bonding and especially ionic bonding. The PVA/PMACa‐DS hydrogels emit varied phosphorescence emission colors from blue to yellow‐green upon excitation with 312–400 nm light, with a maximum lifetime of 13.4 ms. Experiments and theoretical calculations demonstrate that ionic crosslinking between Ca2+ and nonconventional chromophores prevents the contact of the nonconventional chromophores with water molecules and hence restricts nonradiative decay, leading to RTP emission. This work provides a reliable strategy for designing RTP hydrogels with excellent mechanical properties based on nonaromatic polymers for emerging applications.