| Cellulose is an environmentally friendly bio-based polymer,which contains a large number of hydroxyl groups in its structure and is easy to form hydrogen bond networks.Through reasonable design,it is expected to be an excellent durable room temperature phosphorescence(p RTP)material.Organic room temperature phosphorescent materials have the characteristics of low toxicity,low cost,flexible and processable,and are of great significance in biomedical applications,information security,anti-counterfeiting,flexible displays,comfortable wearable devices,photochemical catalysis and other applications.At present,there are two main ways to prepare cellula-based organic room temperature phosphorescent polymers:(1)To prepare RTP materials by physical doping or chemical grafting of cellulose as polymer substrate;(2)RTP materials were prepared by using cellulose as phosphorescent chromophore through hydrogen bond interaction and heteratomic interaction.At present,the research of room temperature phosphorescent materials based on cellulose is mainly focused on improving the phosphorescent life and quantum yield,while the research of room temperature phosphorescent materials with high machinability needs further research,which is the key to the industrialization of room temperature phosphorescent materials.In addition,the accumulation of a large number of hydrogen bonds in cellulose is the main mechanism of cellulose in room temperature phosphorescent materials,and the regulation mechanism of cellulose on phosphorescent behavior and its explanation need to be further clarified.Therefore,it is of great significance to prepare cellulose based room temperature phosphorescent materials with high processability and stimulus response and to reveal the regulation mechanism of cellulose in the phosphorescent process for the development of room temperature phosphorescent materials.In this work,cellulose as the main material,with the "host-guest" interaction strategy of polycyclic aromatic phenanthrene,pyrene doping into hydroxyethyl cellulose or carboxymethyl cellulose two kinds of cellulose containing a large number of hydrogen bonds,can be easily prepared a cellulose-based room temperature phosphorescent material Cel@p RTP.This work by spatial accumulation effect for design strategy,the series of polycyclic aromatic hydrocarbons with amino molecular amidation reaction with carboxymethyl cellulose,another kind of cellulose was prepared at room temperature phosphorescence material CMC-p RTP,the physical properties of two kinds of material structure and optical properties were characterized and analyzed,and two kinds of material process of the optical properties and phosphorescent mechanism.The experimental design of CMC-p RTP with good afterglow effect was carried out to explore its potential application in3 D molding,information encryption and flexible devices.The main conclusions are as follows:1.Using cellulose as polymer skeleton,polycyclic aromatic hydrocarbons containing conjugated units were doped into cellulose rich in hydrogen bonds through "host-guest" interaction to prepare Cel@p RTP composite materials.Cel@p RTP has a good room temperature phosphorescence effect.The two polymers,HEC-Ph T and CMC-Ph T,with phenanthrene as guest doped with small molecules,show dark yellow afterglow,and the afterglow life is between 180 ms and 200 ms.HEC-Ba P and CMC-Ba P,two polymers with pyrene as guest doped small molecules,present red afterglow,and the afterglow lifetime ranges from 150 ms to 180 ms.The mechanism of room temperature phosphorescence of CMC-p RTP is that the semi-rigid matrix in cellulose and the hydrogen bond between pa Hs and matrix protect the guest small molecule phosphorescence process.The room-temperature phosphorescence properties of Cel@p RTP materials confirmed the feasibility of the cellulose/conjugated luminescence composite system,which laid a foundation for the preparation of long-life and multi-functional cellulose based RTP materials.2.Based on the composite system of cellulose/conjugated luminescence groups,the introduction of amide bonds as the facilitators of ISC in the system,and the use of spatial stacking effect for phosphorescent emission tuning by changing the aromaticity of pa Hs small molecules.The CMC-p RTP composite was prepared by grafting the polycyclic aromatic hydrocarbons(PAHs)with amino groups onto carboxymethyl cellulose(CMC)with a certain RTP effect.Small polycyclic aromatic molecules with amino groups in CMC-p RTP successfully polymerize with cellulose to form amide bond structure,and the material is amorphous,which is conducive to the application of deep processing.Cmc-prtp material has excellent thermal stability and mechanical properties with Tg of 300? and young's modulus of 18 Gpa.Cmc-prtp shows good optical properties.The phosphorescence life of C3 can reach820 ms,which belongs to long-life room temperature phosphorescence.The phosphorescence color of C1-C4 material decreases with the aromaticity of the grafted small molecules,resulting in a red shift from cyan to orange-red afterglow,showing color tuning and light activation properties.The color-tunable emission of CMC-p RTP is mainly due to the different spatial accumulation of the aromatic compounds and the interaction between the cellulose chain and the aromatic luminescent groups.The photoactivation characteristics of CMC-p RTP are affected by the dense pore structure of the polymer material.The cellulose/conjugated luminescence composite system has a longer afterglow life than the original system Cel@p RTP,and has the function of light activation and color tuning through the introduction of heteroatoms,the coordination of multiple light groups and the coordination of spatial stacking effect.CMC-p RTP material can be prepared into cube shape,foldable pattern and encrypted image according to the process requirements,reflecting its huge potential application in the fields of Three-Dimensional molding,flexible devices and information encryption. |
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