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Immobilized Enzymatic Synthesis And Characterization Of Water-soluble Conductive Polyaniline

Posted on:2007-06-11Degree:MasterType:Thesis
Country:ChinaCandidate:J G WuFull Text:PDF
GTID:2191360182488781Subject:Chemical Engineering
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Enzymatic synthesis of a water-soluble, conducting polyaniline (PANI) using a template-guided approach was studied in this paper. Horseradish peroxidase (HRP) was used to catalyse the polymerization of aniline in the presence of a new polyanionic template, polyacrylate sodium (PAAS). The effects of reaction system conditions on the polymerization were worked out. Meanwhile, the products were compared with those synthesized using different templates. And what is more, the method for the synthesis of polyaniline with the immobilized horseradish peroxidase enzyme was investigated. At last, as the polyaniline which is gained by the enzymatic catalyse is the powder and it doesn't have the mechanical strength, it has to mix with other substances for practice application, this paper did a junior research on the practice application of polyaniline.In the research of polymerization of PANI by the HRP enzyme solution in the presence of new template PAAS, effects of different buffer solution, concentration of initiator (H2O2), and the molar ratio of aniline to PAAS (based on the monomer repeat unit) on the polymerization were investigated in detail. The PANI was characterized by the UV-vis/near IR, FTTR spectroscopy, thermogravimetric analysis (TGA) and four-point probe conductivity measurement. The results demonstrated that PAAS can be used as the template to synthesize PANI, and the optimum value of the buffer solution was about 3.5, the concentration of H2O2 was expected to be 20 mM, and the best molar ratio of the PAAS to aniline was 4. The conductivity of PAAS/PANI complex was 3.5 ×10~-2 S/cm.In the study of the immobilization of HRP enzyme, HRP was immobilized on the surface of the functional beads which were made from chitosan and alginic acid calcium.The immobilization efficiency, relative activity, reuse times and stability of bead-immobilized HRP were investigated. And the performance of enzymatic polymerization using bead-immobilized HRP was compared with that of polymerization employing HRP solution directly. The results showed that thebead-immobilized HRP could be used successfully in the enzymatic synthesis of PANI, the immobilization efficiency was 66.7%, relative activity was 74%, the bead-immobilized HRP can be reused at least 6 times with a satisfactory stability and after being kept for 72 h, the immobilized enzyme could also retain its activity. The effects of the buffer solution, concentration of H2O2, and the molar ratio of PAAS to aniline on the polymerization were the same to the condition of that using enzyme solution directly.In the junior research of polyaniline's practice application, the epoxy resin whose properties was improved by silane was chosen to be mixed with the polyaniline, and the mechanical strength, resistance against water and the conductivity of the mixture were studied in detail.
Keywords/Search Tags:Horseradish peroxidase (HRP), immobilization, enzyme-catalysed polymerization, polyaniline (PANI), polyacrylate sodium (PAAS)
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