Design,Synthesis And Applications Of Room Temperature Phosphorescent Polymers Based On Organic Phosphine Salts

Room temperature phosphorescent（RTP）materials have been widely used in afterglow lighting devices,information sensing,biological imaging,and anti-counterfeiting encryption owing to their unique photophysical properties and innovative applications.Most of them were limited to molecular crystals,which severely confined their practical applications because of stringent conditions required for the cultivation of the crystalline state.In this context,the development of amorphous organic room temperature phosphorescent materials is of great significance.To solve this problem,the development of organic room temperature phosphorescent polymeric materials is one of the most popular approaches.However,the current RTP polymers development is still in infancy,and further research and improvement are needed in terms of on-demand regulation of photophysical properties,improvement of mechanical properties,and expansion of functional applications.In this thesis,we synthesized a series of luminescence efficiency,long-lifetime,excellent processing performance organic room temperature phosphorescent polymers by copolymerizing acrylamide/acrylic acid with triphenylphosphine phosphorescent rotors derivatives,and demonstrated their applications in the fields of information security and X-ray imaging.The main contents are as follows:1.Conformation-dependent organic room temperature phosphorescence from amorphous polymersOrganic room temperature phosphorescent materials exhibiting reversible changes in optical properties upon exposure to external stimuli have shown great potential in diverse optoelectronic fields.Particularly,dynamic manipulation of response behaviors for such materials is of fundamental significance,but it remains a formidable challenge.In this chapter,we synthesized a series of stimulus-responsive organic room temperature phosphorescent polymers by copolymerizing acrylamide with triphenylphosphine phosphorescent rotors.Upon the change of excitation wavelength from 300 nm to 360 nm,the phosphorescence wavelength of polymer P1 was redshifted from 474 nm to 507 nm,and the phosphorescence color was regulated from blue to green.Experimental results and theoretical calculations revealed that the various molecular conformations of monomers are responsible for the excitation wavelength-dependent（Ex-De）RTP behavior.Impressively,after gaining insights into the underlying mechanism,dynamic control of Ex-De RTP behavior was achieved through thermal energy driven molecular rotations of monomers.Upon increasing of the temperature,and the persistent luminescence color changes from a sky blue to a green under excitation at 300 nm.This is because molecular conformations varied along with the molecular rotations driven by thermal stimulus.To demonstrate the universality of our strategy,the other Ex-De RTP organic room temperature phosphorescent polymers,namely P2-P5,were copolymerized.Eventually,we demonstrate the practical applications of these amorphous polymers in anti-counterfeiting areas due to their controllable response behaviors and excellent processability.2.Organic polymers based on phosphine salts with room temperature phosphorescence and stretchablility propertiesOrganic room temperature phosphorescent materials with stable persistent RTP properties and good mechanical properties have great potential in flexible organic electronics and photonics,but it is still a formidable challenge to develop such materials.Here,we prepared highly stretchable RTP phosphorescent polymers,which enabled by blending ionic RTP polymers and polyvinyl alcohol into polydimethylsiloxane（PDMS）matrix.The emission wavelength of the stretchable organic room temperature phosphorescent material was shifted from 449 nm to 628 nm,by modifying the chemical structure of monomers,and the organic room temperature phosphorescent color changed from blue to red emission.Experimental results revealed that the stretchable organic room temperature phosphorescent polymers have stable persistent RTP properties and good mechanical properties.The E3 materials can be restored to its original length after 100 times of stretching at the maximum strain of 173%,and the deformed region remain stable photophysical properties.Finally,these stretchable materials were processed into stretchable organic room temperature phosphorescent fiber and“safety ink”,which demonstrates the application of stretchable organic room temperature phosphorescent materials in the field of optical information anti-counterfeiting.3.Organic room temperature phosphorescent polymers for efficient X-ray imagingPure organic materials have recently emerged as promising scintillators for X-ray detection and radiography due to their diversified design,low cost,and facile preparation.However,recent progress in efficient radioluminescence has mainly focused on small molecules,which are inevitably associated with processability and repeatability issues.A concise strategy was proposed to prepare radioluminescent polymers that exhibit multiple emission colors from blue to yellow with high brightness in an amorphous state by the radical copolymerization of negatively charged polyacrylic acid and different positively charged quaternary phosphonium salts.One of the obtained polymers exhibited excellent photostability under a high X-ray irradiation dosage of 27.35 Gy and had a detection limit of 149 n Gy s^-1.This performance is superior to that of conventional anthracene-based scintillators.By simply drop-casting of polymer methanol solution on a quartz plate,transparent scintillator screen was successfully fabricated for X-ray imaging with 8.7 line pairs mm^-1 resolution.Overall,the pure organic phosphorescent polymers with highly efficient radioluminescence were demonstrated for the first time,and the strategy reported herein offers a promising pathway to expand the application range of amorphous organic scintillators.