Electrochemical and spectroscopic characterization of poly (bithiophene + 2-methylfuran) copolymer

Effect of surface properties on the electrochemical response of cynarin by electro-synthesized functionalized-polybithiophene/MWCNT/GNP

Cynarin is one of the biologically active functional components present a wide range of pharmacological applications. Herein, we reported the fabrication and surface properties investigation of a new highly sensitive electrochemical sensor for the detection of cynarin. The electrochemical sensors were fabricated in several steps; the first being the synthesis of bi-thiophene derivatives-based monomers 3,3'-bithiophen (M1); 2-methoxy-5-carbaldehyde-[3,3'-bithiophene] (M2) and 2-((2-methoxy-[3,3'-bithiophen]-5-yl)methylene)malononitrile) (M3) followed by electrochemical polymerization on a glassy carbon electrode after which multi-walled carbon nanotube (MWCNT) and gold nanoparticles (GNP's) were electrodeposited layer-by-layer on the polymer coating to obtain multilayer electrochemical sensors. The morphological properties of the formed polymers were evaluated using SEM analysis and the apparent contact angles to preview the changes in surface properties after the functionalization of monomers and therefore their effects on the detection of cynarin. Analytical parameters such as the accumulation time and pH of the PBS solution which influence the sensitivity of the electrochemical sensors were optimized. Under the optimal conditions the GCE/P3/MWCNT/GNP's showed a wide range of analyte concentrations (1 to 100 μM and 0.01 to 1 μM) and detection limit of 0.0095 using pulse differential voltammetry. In addition, the electrochemical sensors showed good reproducibility, stability and selectivity and they were used successfully for the determination of cynarin in real solutions.

Electrochemical behavior, characterization and corrosion protection properties of poly(bithiophene+2-methylfuran) copolymer coatings on A304 stainless steel

Polybithiophene (PBTh), poly(2-methylfuran) (PMeFu) and poly(bithiophene+2-methylfuran) noted poly(BTh+MeFu) copolymer films were synthesized by electrochemical deposition on 304-stainless steel, from an acetonitrile (ACN) solution containing 10−2m bithiophene, 10−2m 2-methylfuran and 10−1m lithium perchlorate (LiClO4), by cyclic voltammetry (CV) between 0 V and 2 V vs. SCE, with a scan rate of 50 mV·s−1. The copolymers coated were studied in a corrosive sulfuric acid medium (H2SO4·1 N) using the potensiodynamique polarization method and the electrochemical impedance spectroscopy (EIS). Copolymers coated characterization was performed using scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The polarization curves show that the copolymer film formed on A304, shifts the corrosion potential towards more positive potentials. The presence of the poly(BTh+MeFu) improves the corrosion resistance of the metal in a corrosive medium, H2SO4. This protection against corrosion is caused by the barrier effect of the layer of copolymer, which covers the surface of the A304 stainless steel against the aggressive ions of the corrosive medium.