Synthesis And Self-assembly Of Molecular Brush Block Copolymer PS-b-PEO With AIE Gens

The AIE effect(Aggregation Induced Emission)refers to the unique fluorescence enhancement phenomenon due to changes in factors such as its spatial conformation and molecular arrangement when the material is in the aggregate state or solid state.In this project,the AIE group was introduced into the molecular brush block copolymer,the self-assembly morphology of the polymer was studied,and the detection application of nitrophenol was carried out.The main work includes the following two aspects:1.In terms of synthesis,we synthesized norbornene-terminated polystyrene(PS)and polyethylene glycol(PEO)macromonomers containing AIE groups(tetraphenylethylene,TPE),and then used ring opening metathesis polymerization reaction produces amphiphilic molecular brush block copolymers(BBCP1-7)with different molecular weights.The polymer was characterized by NMR spectroscopy and 18-angle laser light scattering gel chromatography system(GPC-MALS).The results show that the block ratio is close to 1:1,the number average molecular weight is between 180 and 360 kDa,and the POD is between 1.16 and 1.31.Furthermore,the properties of the polymer solution self-assembly were studied.The solution self-assembly structure of the polymer was obtained by adding different proportions of pure water to the polymer's tetrahydrofuran solution.The structure morphology was studied and the AIE properties were characterized by fluorescence spectrometer.2.Photonic microspheres with different structural colors were prepared by the emulsion-constrained self-assembly method.The structure of the surface and the section was characterized by SEM,and it was found that the assembled structure was a long-range ordered porous inverse opal structure,and the pore size of the same sample was uniform.The pore size of the inverse opal structure can be adjusted by adjusting the length of the main chain of BBCP,the pore size is between 150nm-300nm,and the pore wall is about 30 nm.The nanopores in the unique inverse opal structure of the polymer are interconnected,which will greatly facilitate the diffusion of the analyte into the porous structure for fluorescence quenching.The structural color was characterized by optical microscope and reflection spectrometer.Both polymers obtained blue?red full-spectrum pigments.The reflection wavelength range was 423nm-665nm.It was mixed as a pigment in the hydrogel to obtain an angle-dependent color change fluorescent anti-counterfeiting material.In addition,based on the AIE phenomenon,the self-assembly kinetics of BBCP at the water/oil interface is clearly demonstrated,which provides a new understanding of the organized spontaneous emulsification mechanism.3.Good control of the TPE position in the self-assembled porous structure will bring good performance in ultra-trace detection.At the same time,the hydrogen bond interaction between the phenol group and the PEO layer inside the nanoporous structure promotes the enrichment of the analyte.BBCP7 microspheres have a transparent and uniform porous structure and TPE distributed in the outer PEO section for easy contact with the detection object,and have been selected as the most efficient ultra-trace detection microsensor.After reaching the equilibrium for analyte adsorption and desorption,the concentration of the analyte is highly correlated with the relative PL intensity.Based on this equilibrium,quantitative ultra-trace detection can be achieved.The limit of quantification(LOQ)is as low as 0.15 ppb(ng/L).At the same time,the quenching efficiency of different nitrophenols was tested.Among them,m-nitrophenol(mNP)showed the best quenching effect due to its lowest LUMO energy.In addition,the use of different BBCP microspheres will produce different fluorescence changes to form a characteristic response pattern,which can be used as a sensor array for distinguishing analytes.The differentiation is achieved through linear discriminant analysis(LDA),and the three nitrophenol isomers are divided into three clusters with a 100%success rate.This work demonstrates the useful principles of rational design of molecular structures and self-assembled structures to improve sensing performance,which can potentially be extended to sensor designs for different chemical and biological detection applications.