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Functionalization Of Carbon Nanofubes And Their Application For Electrochemical Sensors

Posted on:2013-04-21Degree:DoctorType:Dissertation
Country:ChinaCandidate:Y G LiFull Text:PDF
GTID:1268330401951389Subject:Polymer Chemistry and Physics
Abstract/Summary:PDF Full Text Request
Covalent functionalization of single-walled carbon nanotubes (SWNTs) with well-defined, azide-derivatized poly(N,N-dimethylacrylamide)-b-poly(N-isopropylacrylam-ide-co-N-acryloxysuccinimide), PDMA-b-P(NIPAM-co-NAS),(f-SWNTs) wasaccompished by nitrene cycloaddition reaction. Subsequently, the co-assembly of thecopolymer and f-SWNT blends was carried out in aqueous solution, leading tothermoresponsive polymeric micelles that adhered to the surface of nanotubes. Thecopolymer aggregates were stabilized and covalently anchored to SWNTs aftercrosslinking with ethylenediamine (SWNT-micelle). In addition, two electrochemicalsensing platforms were developed for the determination of biphenol A (BPA) basedon the immobilization of Fe3O4nanoparticles onto f-SWNTs as well as modificationof nanotubes with melamine. The main research contents were shown as follows:(1) Synthesis and self-assembly of thermoresponsive copolymers. Well-defineddiblock copolymers with azide terminated group, PDMA-b-P(NIPAM-co-NAS) andP(DMA-co-NAS)-b-PNIPAM, were successfully synthesized by reversible addition-fragmentation transfer (RAFT) polymerization. Core and shell cross-linked micelleswere fabricated by ethylenediamine crosslinking. The effect of polymer concentrationas well as copolymer composition (i.e., NAS content) on the self-assembly behaviourof the thermoresponsive copolymers were studied by dynamical light scattering.(2) Co-assembly of copolymers and f-SWNTs. Firstly, covalent functionalizationof SWNTs with block copolymer was accomplished by nitrene cycloaddition, andthen the co-assembly of the copolymer and f-SWNT blends was carried out inaqueous solution. The effect of the concentrations of polymer and f-SWNTs on theresultant co-assembled structures was investigated.(3) Immobilization of magnetic nanoparticles (MNPs) to f-SWNTs (SWNT-MNP)and the application for electrochemical sensing. MNP-NH2was first synthesizedthrough the reaction between MNPs and silane coupling agent. After which it wasimmobilized onto the surface of f-SWNTs through reacting with the NAS units. Theelectrochemical behaviors of BPA at the SWNT-MNP composites modified electrodeexhibited remarkable electrocatalytic behaviors for BPA. Therefore, a quick andsensitive electroanalytical method was developed for the determination of BPA.Under optimized conditions, a good linear relationship between the oxidation peakcurrent and its concentration was obtained in the range of0.005~8.43μM, with a limit of detect of1.21nM.(4) The application of MWNT/melamine complex (MWNT-MAM) for electro-chemical sensing. MWNT-MAM was synthesized through modification of MWNTwith melamine, and a novel electrochemical sensor for the determination of BPA inwater was fabricated by immobilization of MWNT-MAM onto the surface of glassycarbon electrode. The cyclic voltammetry results showed that the sensor exhibitedstrong catalytic activity toward the oxidation of BPA with a well-defined cyclicvoltammetric peak at0.56V. Therefore, a quick, direct and sensitive electrochemicalmethod for the determination of BPA was developed. Under optimal conditions, theelectrochemical sensor exhibited a wider linearity range from10.0nM to40.8μMBPA with a detection limit of5.0nM (S/N=3). This novel sensor was successfullyapplied to determine BPA leached from real plastic samples with good recovery,ranging from96%to102%.
Keywords/Search Tags:Carbon nanotubes, Thermoresponsive block copolymer, Nitrene cycloaddition, Self-assembly, Electrochemical sensor
PDF Full Text Request
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