Application Of Aggregation-induced Emission Effect In Visual Monitoring Of Polymer Microstructure Evolution Process

Amphiphilic block copolymers would generate nanostructures with a variety of morphologies during self-assembly process,including spherical,rod-shaped,vesicle,sheet,and composite micelles.Benefiting from the development of living polymerization technology,the types and proportions of structural units of block copolymers could be easily adjusted.The diverse structures and morphologies guaranteed a wide range of application fields,such as biomedicine,nanomaterials and cell recognition.However,the existing detection technologies for self-assembly are discontinuous and invasive,which failed to efficiently realize real-time monitoring of the continuous process of self-assembly.The development of a continuous,convenient and non-invasive self-assembly structure monitoring technology is of great significance for both scientific research and industrial generation.In this thesis,a series of amphiphilic block copolymers labeled with fluorescent molecules were designed and synthesized.The continuous visual monitoring of the self-assembly process was realized owing to the sensitivity of aggregation-induced emission(AIE)effect to the microenvironment.The specific work is:(1)Visual monitoring of polymer self-assembly through the copolymerization of AIE monomersThe TPEE monomer with AIE characteristics was selected as the fluorescent probe,and the amphiphilic block copolymer(PS-co-TPEE)-b-P(OEGA)was prepared by ATRP reaction.In the process of self-assembly,the assembly was characterized by fluorescence spectroscopy,transmission electron microscope and other equipment.The results showed that the structure and morphology of the assembly had an obvious correlation with the fluorescence of the system,which proved the feasibility of this method.(2)Visual monitoring of polymer self-assembly through AIE initiatorThe ATRP initiator with AIE characteristics was prepared by the reaction of 4-(1,2,2-triphenylvinyl)phenol(TPE-OH)and ?-bromophenylacetic acid.Block copolymers with TPE groups at the hydrophilic and hydrophobic chain ends were prepared by ATRP reaction.In the monitoring of the self-assembly process of the two copolymer,it was found that when the similar self-assembly structure and morphology appeared,the fluorescence performance of the two was very different.This indicates that the fluorescence of the TPE group in the system was formed by the aggregation of hydrophobic segments after self-assembly and was almost unaffected by the change of solvent,which proves the accuracy of this method.(3)Visual monitoring of the polymerization-induced self-assembly(PISA)processIn order to verify whether this method had practical significance,TPEE monomer was used to monitor the polymerization-induced self-assembly process.The P(OEGA)macromolecular chain transfer agent was prepared by RAFT polymerization,and the subsequent chain-extension reaction was carried out in ethanol and a small amount of TPEE monomer was added.During the PISA process,the molecular weight,selfassembly morphology and fluorescence of the product were monitored.The results show that the fluorescence of the system has a linear relationship with the molecular weight,and has an obvious correlation with the hydrodynamic diameter of the selfassembly objects.It realized the monitoring of the polymerization process and the assembly process at the same time.Compared with the physical blending method,it had much higher sensitivity.