Preparation And Sensing Application Of Conducting Polymer/Functionalized Cellulose Composite Materials

In this study,the different modified electrodes were prepared mainly from conducting polymers and carboxylated nanocrystalline cellulose(CNCC)through electrochemical polymerization.The electrochemical sensors based on these modifed electrodes were developed to detect several electrochemical active small molecules.The main contents of this thesis are summarized as follows:(1)Based on layer-by-layer self-assembly,negatively charged CNCC and positively charged poly(diallyldimethyl ammonium chloride)(PDDA)were alternatingly assembled on the surface of a glassy carbon electrode to form relatively uniform polyelectrolyte multilayer nanocomposite(CNCC/PDDA)_n.It was then incorporated into a matrix of conducting poly(3,4-ethylenedioxythiophene)(PEDOT)electrodeposited on the surface of the electrode.The nanocomposites were prepared in various ratios of PEDOT and(CNCC/PDDA),and then characterized by transmission electron microscopy,scanning electron microscopy,electrochemical impedance spectroscopy,cyclic voltammetry,and differential pulse voltammetry.The PEDOT/(CNCC/PDDA)4 nanocomposite showed the lowest electrochemical impedance and best electrocatalytic activity towards the oxidation of nitrite.Based on these findings,an amperometric sensor was developed which,if operated at 0.80 V(vs.SCE),can detect nitrite in the 0.2 ?M to 1.73 mM concentration range with a 57 nM detection limit.(2)Ag nanoparticles with uniform size were prepared and dispersed uniformly on the surface of CNCC using NaBH4 as reductant.Novel conducting polymer nanocomposites of PEDOT doped with AgNPs/CNCC were deposited on the GCE by electrochemical method.The prepared nanocomposites were characterized by scanning electron microscopy,transmission electron microscope,electrochemical impedance spectroscopy,cyclic voltammetry and differential pulse voltammetry.The prepared PEDOT/AgNPs/CNCC showed very low electrochemical impedance and good electrocatalytic activity to dopamine and paracetamol.Based on the excellent catalytic activity of the PEDOT/AgNPs/CNCC towards the oxidation of dopamine,a sensitive amperometric sensor for the detection of DA with a detection limit of 16.6 nM was developed.(3)Au nanoparticles with uniform size were prepared and dispersed uniformly on the surface of CNCC using Na BH4 as reductant.Novel conducting polymer nanocomposites of PEDOT doped with AuNPs/CNCC were deposited on the glassy carbon electrode by electrochemical method.The prepared nanocomposites were characterized by scanning electron microscopy,transmission electron microscope,electrochemical impedance spectroscopy,cyclic voltammetry and differential pulse voltammetry.The prepared PEDOT/AuNPs/CNCC showed very low electrochemical impedance and good electro catalytic activity to ascorbic acid.Based on the excellent catalytic activity of the PEDOT/AuNPs/CNCC towards the oxidation of ascorbic acid,a sensitive amperometric sensor for the detection of ascorbic acid with a detection limit of 0.29 ?M was developed.Operated at-0.15 V,the sensor can detect ascorbic acid in the range of 0.88 ?M to 15021 ?M.