Search

Mesoporous silica (SiO2) nanoparticles were prepared using the cationic surfactant cetyltrimethylammonium bromide as a soft template in a basic medium. The particles were coated with a carbon layer through a facile hydrothermal process. The carbon-coated mesoporous SiO2 (C#SiO2) nanoparticles were used as core for the in situ chemical-oxidative polymerization of conductive polypyrrole (PPy). The structure and morphology of the PPy/C#SiO2 nanocomposites were analyzed by transmission electron microscopy, wide-angle X-ray diffraction, and Fourier transform infrared spectroscopy. A glassy carbon electrode was modified with the PPy/C#SiO2 nanocomposites. The performance of the modified electrode for the dopamine (DA) detection was examined by cyclic voltammetry, electrochemical impedance spectroscopy, and differential pulse voltammetry. The modified PPy/C#SiO2 glassy carbon electrode exhibit large peak currents for the DA oxidation reaction, suggesting the electrochemical performance of the nanocomposites is enhanced. The impedance evaluation of the fabricated PPy/C#SiO2 nanocomposites reveals a very small charge-transfer resistance. Additionally, the nanocomposites showed a linear response for DA detection in the concentration range of 1 × 10−6 to 2 × 10−4 M with a detection limit of 7.6 × 10−7 M (S/N = 3). Moreover, DA detection was successful in the presence of uric acid and l-ascorbic acid. Due to their outstanding electrochemical performance, the PPy/C#SiO2 nanocomposites may be considered for the DA detection devices.

In this study, the foaming of nonwoven fabrics and bulk polymers was investigated. Four different polymers that are commonly used for textiles including polyethylene terephthalate, thermoplastic polyurethane, thermoplastic polyether ester elastomer and polypropylene were foamed by batch foaming. Among the polymers, thermoplastic polyurethane seems to be the most promising material since it possesses the highest cell density and smallest cell size. In addition, nanoclay was added to thermoplastic polyurethane to promote cell nucleation and to increase the cell density. The results showed that well dispersed nanoclay in thermoplastic polyurethane served as an excellent nucleation agent and the cell structure was improved. The cell size of thermoplastic polyurethane nanocomposite foam decreased to 1 µm while the cell density increased to 3 × 1011 cells/cm3.