Design,Fabrication And Properties Of Polymer-based Room Temperature Afterglow Materials

Inorganic afterglow materials are highly valued for their exceptional luminescence properties and have been extensively developed for use in energy and light-emitting diode applications.However,the preparation of these materials requires the doping of heavy metals,which significantly increases the cost of raw materials.Moreover,these metal elements are biotoxic and even radioactive,posing a potential hazard to both human health and the environment.Furthermore,the process of preparing the materials requires a complex procedure and a high temperature exceeding 1,000 degrees.Additionally,there is a shortage of inorganic afterglow materials in the infrared or near-infrared range,which limits their ability to meet the demands of optical display and other industries.As a result,organic afterglow materials have emerged as a viable alternative due to their lower cost,relative environmental friendliness,and biocompatibility.Organic afterglow materials have shown superior performance in various fields compared to inorganic afterglow materials.Moreover,due to the distinctive properties of organic molecules,researchers have developed unique organic afterglow materials for specific applications such as oxygen monitoring and molecular sensing.Polymer-based room-temperature afterglow materials are a crucial component of organic afterglow materials,with significant accomplishments in optical display and information encryption.However,the majority of reported polymer-based afterglow materials are created through solution casting and melt casting processes.Unfortunately,these methods often necessitate the use of toxic solvents for slow evaporation or higher temperatures to melt the polymer.Moreover,most conventional polymer afterglow materials are in a solid phase,which restricts their potential applications.To overcome these two major limitations of polymer afterglow materials,we have conducted the following research.1.Polymer-based room-temperature afterglow materials based on various polymerization monomers were prepared via photoinitiated bulk polymerization.By adding photoinitiators to solutions of monomers dissolved with light-emitting molecules and exposing them to UV irradiation for a short term,we successfully obtained room-temperature phosphorescent(RTP)materials with exceptional afterglow properties.We found that increasing the dipole moment of polymer chains results in a longer afterglow time,as demonstrated through our experimentation with different types of monomers.In fact,we received a remarkable afterglow life of 1.46 seconds.Our findings suggest that this increase in dipole moment reduces the exciton singlet level,which in turn promotes intersystem crossing and facilitates efficient phosphorescence emission.Furthermore,we have shown that the bulk polymerization strategy is just as effective as melt casting and solution casting.To enhance this strategy,we introduced a thermal annealing process and conducted experiments to illustrate the impact of oxygen and initiator on system performance.To expand the potential applications,we developed 3D afterglow materials and flexible afterglow materials,both of which exhibited impressive afterglow effects.2.Aqueous afterglow materials were prepared by co-assembling luminescent molecules with block copolymers.Polyethylene glycol-poly(methyl methacrylate)copolymers(PEG-PMMA)with varying hydrophilic and hydrophobic segment lengths were synthesized via reversible addition-fragmentation chain transfer(RAFT)polymerization.The co-assembly of luminescent molecules with block copolymers resulted in RTP in the aqueous phase,with an afterglow lifetime of over 1.0 s.Three luminescent molecules based on the acridone skeleton were designed and synthesized,of which one was selected and doped with a small molecular matrix.This was co-assembled with copolymers to produce micelles with an aqueous-phase delayed fluorescence lifetime of over 200 ms.Dynamic light scattering and transmission electron microscopy showed that the micelle particles ranged in size from 44 to 220 nm,with either spherical or worm-like morphology.