Synthesis And Properties Of Star-shaped Polyacrylamide Fluorescent Polymers

In recent years,non-conjugated polymer systems can be widely used in the field of biomedical materials due to their excellent biocompatibility and unique fluorescent luminescence properties,which has attracted the interest of more and more scientific researchers.The rapid development of life sciences greatly promote the study of fluorescence emission of non-conjugated polymers,which include luminescence phenomenon,luminescence mechanism and its applications.Existing research on fluorescence luminescence of non-conjugated polymers mostly focuses on hyperbranched polymers with better structural rigidity after clusters,but the research on fluorescence luminescence of star-like non-conjugated polymers is less involved.Therefore,the design and synthesis of star-like non-conjugated polymers are of great significance to enrich the research and application of non-conjugated polymers.In this paper,star-like polyacrylamides with different numbers of arms and different molecular weights were designed and synthesized,and the influence of the number of arms and the molecular weight of the arms on the fluorescence properties of star polymers was studied.The specific work is as follows:Six-arm polyacrylamide,twelve-arm polyacrylamide and eighteen-arm polyacrylamide(Tpo-(PAMn)6,Epd-(PAMn)12,Ted-(PAMn)18 respectively)were synthesized by the first nucleus and second arm method.The polymer prepared in present paper has the advantages of simple synthesis method,easy-to-control structure,excellent water solubility and strong fluorescence emission intensity.The chemical structure of the target polymer was determined by hydrogen nuclear magnetic spectroscopy(1H-NMR)and multifunctional imaging photoelectron spectrometer(XPS),and the molecular weight and molecular weight distribution of the polymer were characterized by gel permeation chromatography(GPC).Optical characterization was carried out by ultraviolet-visible spectrophotometer,fluorescence spectrophotometer,absolute quantum yield measurement system and laser confocal microscope.The results showed that the fluorescence luminescence performance of star-like polyacrylamide not only depends on its concentration change,but also depends on its concentration.In the arm structure determined by the number of arms and the molecular weight of the arm.Tpo-(PAMn)6 and Epd-(PAMn)12 show similar aggregation-induced emission(AIE)fluorescence emission phenomenon,while Ted-(PAMn)18 and linear polyacrylamide PAM show similar aggregation-caused quenching(ACQ)fluorescence emission phenomenon.The arm number inspection experiment shows that the fluorescence of Tpo-(PAMn)6 is stronger than that of Epd-(PAMn)12 and Ted-(PAMn)18.The branch molecular weight inspection experiment shows that it is not that the greater the molecular weight of the branch arm,the stronger the fluorescence emission intensity when the number of arms is the same.Star-like polyacrylamide fluorescence has excitation wavelength dependence,which as the excitation wavelength increases,the emission wavelength red-shifts.The unique fluorescence emission phenomenon caused by the aggregation of heteroatoms to form different clusters(chromophores).Finally,the effects of 11 cations on the fluorescence emission of Ted-(PAM33)18 were studied,and Fe3+showed prominent fluorescence quenchability.When the concentration of Fe3+ is in the range of 0.1?0.8?mol/L,the fluorescence intensity decreases linearly,and when it rises to 1 × 103?mol/L,the fluorescence of the system is almost completely quenched.This provides the possibility for the application of this type of star-like polyacrylamide in the field of Fe3+ detection.