The Synthesis Of Carbazole-labeled Hydrophobically Modified Polyacrylamide And The Study Of Its Fluorescence Properties

Because of their good viscoelasticity and shear resistance,hydrophobic associating water-soluble polymers exhibit a broad application in the field of enhancing oil recovery(EOR)used as polymer flooding.However,most related research focused on phenomenological description and evaluation of hydrophobic associated polymers solution with specific composition and structure.There is no clear understandings in microstructure of polymer solution due to limitation of characterization method,which results in a lack of guidance for application of associative polymers.For this reason in this thesis,fluorescent group carbazole was introduced into the molecular chains of polyacrylamide,and the fluorescent properties of this polymer were studied.Because carbazole units were also hydrophobic component,thus association behaviors of hydrophobic associating water-soluble polymer solution could be investigated by fluorescence spectrum directly,which provide alternative way to analyze the microstructure of associative polymer solution.The main results of this research contain following aspects:(1)Series carbazole labeled hydrophobically modified polyacrylamide have been synthesized by copolymerization of N-vinyl carbazole and acrylamide.A co-solvent ethanol was selected as the reaction medium for the precipitation polymerization in order to reach a compromise between the distinct difference in solubility and activity of the two monomers.Meanwhile,the carbazole labeled polymers were characterized by the FTIR,UV and]H NMR,which demonstrated N-vinyl carbazole and acrylamide were copolymerized successfully by comparing the results with that of the pure polyacrylamide.According to calculation of the characteristic peak area of 1H NMR diagram,it could be found that the content of carbazole monotonously changes with its feed ratio of comonomers.Therefore the structure of the carbazole labeled associating polymer can be easily regulated by varying the feed ratio.(2)Steady-state fluorescence of the carbazole labeled hydrophobic modified polyacrylamide was examined at different concentration.Concentration dependence of fluorescence excitation spectra and emission spectra of carbazole labeled polyacrylamide aqueous solution were studied in three concentration regions.Based on the concentration dependence of association behaviors,the influence of concentration on steady-state fluorescence spectrum was attributed to effect of formation of carbazole aggregates.Thus the microstructure of carbazole labeled polyacrylamide could be investigated by steady-state fluorescence spectrum at the condition that fluorescence excitation spectrum and emission were correlated with association behavior.(3)The interaction between different metal ions and carbazole labeled hydrophobic modified polyacrylamide was investigated.The results showed that the addition of Na+?Mg2+?Ca2+?Hl3+?Zn2+?Cu2+ has no apparent influences on the fluorescent property of carbazole labeled hydrophobic modified polyacrylamide,except for Fe3+.Thus,the fluorescence quenching mechanism of carbazole labeled hydrophobic modified polyacrylamide was analyzed in details.It suggested that the quenching level of fluorescence has nothing to do with the concentration of carbazole labeled hydrophobic modified polyacrylamide,which is based on the inner-filter effect of fluorescence.The work provides a new aspect for the application of carbazole labeled hydrophobic modified polyacrylamide.