Preparation And Sensing Application Of Conducting Polymer/Ionic Liquid Composite Materials

In this study, new composites of conducting polymers doped with different ionic liquids(IL) were prepared through electrochemical polymerization, and their microstructure, composition, and electrochemical performances were characterized with varous technologies. Experimental results showed that these composites had excellent electrochemical and antifouling properties, which can promote the development of antifouling materials and electrochemical sensors. The main contents of this thesis are summarized as follows:(1) A conducting polymer based composite material of poly(3,4-ethylenedioxythiophene)(PEDOT) doped with pure insoluble IL,1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide, was prepared through a cost-effective electrodeposition method. A very tiny amount of insoluble IL(less than15 μL), containing 0.1 M conducting polymer monomer, was drop-coated on an electrode surface and then used for electropolymerization using a homemade electrochemical cell filled with aqueous supporting electrolyte. With this design, the consumption of expensive IL for the preparation of the PEDOT/IL composite was greatly reduced, and thus effectively reduced the cost. The prepared PEDOT/IL composite was found to be highly conductive and stable, and it exhibited a highly nanoporous microstructure and excellent electrocatalytic activity toward the oxidation of dopamine(DA). Based on the excellent stability and electrocatalytic activity of the PEDOT/IL nanocomposite, a highly stable, sensitive and selective DA sensor with a detection limit of about 51 n M was developed.(2) A conducting polymer nanocomposite, PEDOT doped with pure ionic liquid 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide(PEDOT/IL),was electrochemically synthesized and used for antifouling electrochemical sensing.The PEDOT/IL composite exhibited superior antifouling ability owing to its porous microstructure(target screening effect) and good hydrophilic property(reduce nonspecific protein adsorption associated with hydrophobic interactions). Combing excellent conductivity and antifouling ability, the PEDOT/IL composite can be used for the development of novel electrochemical sensors capable of detecting small molecules like dopamine directly in complex biological media.(3) A novel conducting polymer PEDOT doped with water soluble ionic liquid(SIL) 1-Butyl-3-methylimidazolium tetrafluoroborate(PEDOT/SIL), was prepared by electrochemical polymerization(cyclic voltammetry and potentiostatic method). The surface morphology and element composition of the above prepared composites were characterized by Scanning Electron Microscopy(SEM), Energy Dispersive X-ray Spectroscopy(EDS) and Raman Spectroscopy. Moreover,PEDOT/SIL composites exhibit excellent conductivity and large specific surface area,which makes them suitable for the development of electrochemical sensors for the detection of nitrite and DA. Under optimal conditions, the sensor showed good catalytic activity towards the electrochemical reduction of nitrite with a linear range from 0.5 μM to 2.45 m M and a low detection limit of 169 n M(S/N = 3). Moreover, the catalytic ability of the modified electrode to DA was also excellent, and it possessed a detection range form 0.2-683.4 μM and a detection limit of 67 n M(S/N = 3), and it can selectively detect DA in the presence of ascorbic acid and uric acid without suffering from interference.