Patterned functionalisation of conducting polymer films

Heavy metals have serious detrimental effects on human health and the environment, even at low concentrations. Therefore, the need to monitor these ions has become an urgent global issue. Although there are many analytical techniques used for the determination of metal ions, electrochemical sensors have a number of advantages, notably construction of small and portable devices with high performance. The application of functionalised polymers as sensing elements offers a means to control selectivity and sensitivity in the detection of metal ions in a solution. In addition, patterned surfaces creates the possibility to form two-dimensional, spatially heterogeneous film surfaces with diverse chemical functionalities. This thesis describes fabrication of patterned electrodes using photolithographic technique for detection of metal ions. Synthetic methods to introduce receptor functionalities into polymer surfaces were developed. This study successfully generated films of two derivatives of pyrrole, aniline and thiophene monomers, which contain carboxylic and amino free groups, through potentiodynamic electropolymerisation. Then, the protection of amino and carboxylic acid groups was performed by using fluorenylmethyloxycarbonyl chloride and pentafluorophenol groups, respectively. Polymerization and electrochemical behaviours of all films were studied and monitored using cyclic voltammetry and EQCM techniques. In the next step, patterned polymer films were made by using a photolithographic technique to control functionalisation of polymer surfaces. Then, patterned ester polymer films were reacted with the Nα,Nα-bis(carboxymethyl)-L-lysine and amide polymer films with 2-hydroxyquinoline-4- carboxylic acid. The prepared patterned films (with receptors) were used as electrochemical sensors to detect copper, nickel and cobalt ions at different concentrations in aqueous solution. The voltammetric responses as a function of scan rate were used to determine metal ion uptake and electroactivity. These films gave interesting results for detection of these heavy metals down to 1 ppm. The detection of metal ions was studied as a function of concentration to fit the data to the Langmuir, Frumkin, Temkin and Freundlich isotherms. The relative features of these isotherms were discussed to most appropriately select the isotherm model.