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A novel amphiphilic redox-active copolymer was successfully synthesized using vinylferrocene(VF)as functional monomer. The obtained copolymers were used to non-covalently modify carbon nanotubes(CNTs)to solve the dispersing problem of CNTs and meanwhile preserve its original structure and properties. A uniform CNTs aqueous dispersion was achieved through co-assembly of copolymers and CNTs in selective solvents. Then, the CNTs dispersions were uniformly casted onto the surface of Au electrode to construct nanocomposite sensing films for nitrite determination. Transmission Electron Microscope(TEM)was used to observe the morphologies of the modified CNTs. Scanning Electron Microscope(SEM)and electrochemical workstation were employed to characterize the effect of CNTs content on surface morphologies and detecting performances of the prepared nanocomposite sensing films. TEM results showed that colloid nanoparticles were formed and physically attached to the surface of CNTs, which stabilized CNTs in aqueous solvent through electrostatic/steric repulsive forces between each other. And also, with the increase of CNTs content, the colloid nanoparticles aligned with CNTs diminished. From SEM results, a uniform aggregation of colloid nanoparticles aligned with CNTs was formed, and the formation of microstructures which were beneficial to the increase of specific surface area were found at the prepared sensor film. The existence of the redox-active moieties on the side of polymer chains could efficiently decrease the oxidation voltage of nitrite due to its electrochemical catalysis activity. In addition, CNTs could improve the electrical conductivity of the sensor films, with the increase of CNTs content, the detecting responses enhanced. By combining the outstanding electrical property of CNTs and the redox-activity of the synthetic copolymers, as well as the microstructures of the prepared sensor film, the sensing film achieved a fast and high response with a wide liner range of 1—2 000μmol/L and a low detection limit of 0. 29μmol/L under optimizing conditions. And also, the nitrite sensor showed good selectivity and long term stability. [ABSTRACT FROM AUTHOR]

Three cationic surfactants containing double bond of acrylate-ethyl dimethyl (octyl, dodecvl, cetyl) ammonium bromide were synthesized and characterized by IR and UV-Vis spectra. Next, a new type of hydrophobic associated copolymers was synthesized by using these three surfactants as hydrophobic monomers and using acrylamide as a hydrophilic monomer in presence of ammonium persulfate/sodium hydrogen sulfite initiator. The surface activities of the surfactant monomers and the amphiphilic copolymers by the surface tension method were investigated. For three monomer surfactants, the efficiency of reducing surface tension increased with chain length, that is to say, the critical micelle concentrations (cmc) decreases with increasing of carbon numbers. And, the ability of reducing surface tension, ycmc, decreases with the chain length due to the looser arrangement at air/solution interface because of molecular section area increasing. The surface tension curve of amphiphilic copolymers exhibits two break points, critical aggregation concentration (cac) and cmc, which indicates that the intramolecular micelles are formed at the low concentration and the intermolecular micelles are formed at higher concentration. [ABSTRACT FROM AUTHOR]