Construction And Properties Of Functional Room Temperature Phosphorescent Polymers

Room temperature phosphorescent materials have the characteristics of long lifetime and large Stokes shift,which exhibit excellent properties and application prospects that fluorescent materials do not have in the fields of biological imaging and information encryption.Compared with inorganic phosphorescent materials and noble metal complex phosphorescent materials,organic materials have the advantages of low cost,easy preparation,and low toxicity.With the characteristics of easy synthesis,abundant hydrogen bond cross-linking network and abundant intermolecular interactions with chromophores,rigid polymer systems are an important means to construct room temperature phosphorescent materials.In order to promote the diversification and functionalization of the raw materials of the room temperature phosphorescent polymer system and make the preparation of the phosphorescent materials simpler,a room temperature phosphorescent material with natural lignin as the chromophore was designed in this paper.Lignin(LA-H)was extracted with ethanol and then doped into polyvinyl alcohol(PVA)to obtain excitation wavelength-dependent color-tunable room temperature phosphorescence emission.The abundant hydrogen bond network in the PVA matrix effectively disperses and immobilizes LA-H,fully suppresses the aggregation-induced phosphorescence quenching and the non-radiative transition process of excited triplet states,and realizes the multicolor luminescence of LA-H and the naked eye distinguishable long lifetime.The experimental data and theoretical calculations show that the smaller fragments containing phenolic anion generated after hydrolysis are the basis for the luminescence of the alkalized lignin.The exploration of the luminescence mechanism of alkali lignin lays a foundation for the further development of room temperature phosphorescence properties of other chiral bio-molecules.The application of optical anti-counterfeiting and other aspects is realized by utilizing the unique humidity responsiveness and long afterglow luminescence of the polymer hydrogen bond network.In order to further enrich the functions of the existing room temperature phosphorescent polymer systems,a pair of binaphthyl axis chiral chromophore monomers were reported in Chapter 3,which exhibited obvious circularly polarized room temperature phosphorescence emission after radical copolymerization with acrylamide.In addition,the introduction of HBr into the polymer system by utilizing the external heavy atom effect could effectively enhance its room temperature phosphorescence emission performance,and then smart switch materials with acid-base response were prepared.The experimental results also show that the acid-base responsive long-persistence luminescent polymer has potential application value in the preparation of dual anti-counterfeiting materials.Near-infrared long-lived luminescent materials have the advantages of strong penetration,avoidance of biological fluorescence background interference,and long luminescence lifetime,which have important research value in the field of biological imaging.Using triplet excited state to singlet excited state energy transfer(TS-FRET)formed between a phosphorescent energy donor and a long-wavelength fluorescent energy acceptor is an ingenious approach to obtain near-infrared long-lived luminescent materials.Based on the research on the circularly polarized room temperature phosphorescence system in Chapter 3,in Chapter 4,a long-lived near-infrared luminescent polymer was prepared by co-doping with chiral binaphthyl derivatives as the donor and porphyrin as the acceptor.Studies have shown that the fluorescence emission lifetime of porphyrin acceptors is significantly improved by TS-FRET.At the same time,the chiral luminescence properties of the donor binaphthyl are also transferred to the acceptor porphyrin,realizing the transfer of circularly polarized luminescence in amorphous polymers.This strategy has positive guiding significance for the further design of circularly polarized luminescent materials with near-infrared long lifetime.