Inverse opals are three-dimensional ordered macroporous materials whose pores are arranged in a hexagonal array with interconnected pore channels. These unique structural attributes provide an excessive surface area with facile...
We demonstrate a water-based synthetic route to fabricate composite inverse opals for simultaneous detection of ascorbic acid (AA), dopamine (DA), and uric acid (UA). Our process involves the conformal deposition of poly(3,4-ethylenedioxythiophene) (PEDOT) and PEDOT/Au on the skeletons of Ni inverse opals via cyclic voltammetric scans (CV) to initiate the electropolymerization of 3,4-ethylenedioxythiophene (EDOT) monomers. The resulting samples, Ni@PEDOT, and Ni@PEDOT/Au inverse opals, exhibit a three-dimensional ordered macroporous platform with a large surface area and interconnected pore channels, desirable attributes for facile mass transfer and strong reaction for analytes. Structural characterization and material/chemical analysis including scanning electron microscope, X-ray photoelectron spectroscopy, and Raman spectroscopy are carried out. The sensing performances of Ni@PEDOT and Ni@PEDOT/Au inverse opals are explored by conducting CV scans with various concentrations of AA, DA, and UA. By leveraging the structural advantages of inverse opals and the selection of PEDOT/Au composite, the Ni@PEDOT/Au inverse opals reveal improved sensing performances over those of conventional PEDOT-based nanostructured sensors.
A simple and effective synthetic approach is demonstrated for the formation of uniform hollow polypyrrole (PPy) microcapsules. This process entails the preparation of homogeneous polystyrene@polypyrrole (PS@PPy; core@shell) microspheres, followed by chemical extraction of the PS cores. By proper dispersion of monodispersive PS microspheres and pyrrole molecules in a water/ethanol cosolvent to minimize the diffusion of pyrrole molecules to the PS microspheres, we are able to prepare uniform PS@PPy microspheres with significantly reduced size variation, deformation, and aggregation. The PS microspheres, in diameter of 490 nm, carry negative surface charges, and after the deposition of PPy, reveal a transition from positive to negative surface charges with increasing pH values. The hollow PPy microcapsules, in diameter of 527 nm and shell thickness of 20 nm, are fabricated after selective removal of PS cores from the PS@PPy microspheres in tetrahydrofuran. Analysis tools including Fourier transform infrared spectroscopy, thermogravimetric analyzer, and zeta potential, as well as scanning and transmission electron microscopes are employed for material characterization.
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