Jinshan Guo

Crosslinked polyaniline nanorods with improved electrochemical performance as electrode material for supercapacitors

To improve the electrochemical performance of polyaniline (PANI), crosslinked polyaniline nanorods (CPANI) were prepared via the chemical oxidative copolymerization of aniline with p-phenylenediamine (PPDA) and triphenylamine (TPA). Their morphology and structure were compared with polyaniline (PANI) via transmission electron microscopy (TEM), scanning electron microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), X-ray powder diffraction (XRD) and thermogravimetric analysis (TGA) techniques. CPANI nanorods exhibited an improved electrical conductivity (33.3 S cm−1) in comparison with PANI (4.26 S cm−1). Its electrochemical performance was studied by galvanostatic charge–discharge (GCD), cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) tests. CPANI nanorods exhibited a maximum specific capacitance of 455.1 F g−1 at a scan rate of 1 mV s−1 in a 1.0 mol L−1 H2SO4 electrolyte, which is much higher than that of PANI (286.7 F g−1). Note that the cycling stability of CPANI electrode was improved significantly by chemical crosslinking, and showed higher capacitance retention after 1300 cycles.

Functionalized Graphene Oxide Nanoparticles for Cancer Cell-Specific Delivery of Antitumor Drug

The unique reduction-triggered functional graphene oxide nanoparticles (GON) with well-defined size and uniform distribution were designed as an innovative drug delivery platform for cancer treatment for the first time, via the redox radical polymerization of methacrylic acid from the polyethylene glycol (PEG) modified GON (GON-PEG), following by cross-linking with cystamine. Thermogravimetric analysis demonstrates that the typical PMAA2-GON-PEG carriers contain about 16 wt % PEG segments and 33 wt % poly(methacrylic acid) (PMAA) brushes. PEG moieties are incorporated to make the drug delivery platforms stealthy during blood circulation. Notably, introducing the cross-linked PMAA brushes efficiently minimizes the premature release of doxorubicin (DOX) in the stimulated normal tissues, and accelerates DOX release in the stimulated tumor tissues through response to reduce agent. The carriers showed a 6-fold faster releasing rate at pH 5.0 in the presence of 10 mM glutathione (GSH) (stimulated tumor tissues) than at pH 7.4 with 10 μM GSH (stimulated normal tissues). In vitro cytotoxicity test also showed that the cross-linked PMAA2-GON-PEG (CPMAA2-GON-PEG) carriers had remarkable cytocompatibility, and that the DOX-loaded CPMAA2-GON-PEG had excellent killing capability to SiHa cells.

Crosslinked Carbon Nanotubes/Polyaniline Composites as a Pseudocapacitive Material with High Cycling Stability

The poor cycling stability of polyaniline (PANI) limits its practical application as a pseudocapacitive material due to the volume change during the charge-discharge procedure. Herein, crosslinked carbon nanotubes/polyaniline (C-CNTs/PANI) composites had been designed by the in situ chemical oxidative polymerization of aniline in the presence of crosslinked carbon nanotubes (C-CNTs), which were obtained by coupling of the functionalized carbon nanotubes with 1,4-benzoquinone. The composite showed a specific capacitance of 294 F/g at the scan rate of 10 mV/s, and could retain 95% of its initial specific capacitance after 1000 CV cycles. Such high electrochemical cycling stability resulting from the crosslinked skeleton of the C-CNTs makes them potential electrode materials for a supercapacitor.

Improving cyclic stability of polyaniline by thermal crosslinking as electrode material for supercapacitors

The poor cyclic stability of polyaniline restricts its application as an electrode material for supercapacitors, due to the volume changes during the long charge/discharge process. In this work, a thermal crosslinking strategy was developed to improve the cyclic stability of polyaniline electrode materials by thermal treatment of the conventional linear polyaniline (PANI). The heat-treatment conditions including the temperature, atmosphere and time were investigated. Morphology analysis indicated that crosslinked polyaniline (CPANI) had a rougher surface than that of the linear PANI, which could be expected to result in a higher specific area. Compared to the linear PANI, the electrical conductivity of the CPANI increased with the increase of treatment temperature at first and then decreased. The CPANI sample by thermal treatment at 140 °C in air showed the highest electrical conductivity of 6.78 S cm−1. As an electrode material for supercapacitors, the CPANI exhibited an improved electrochemical performance than the linear PANI. After 1300 CV cycles, the CPANI electrode still retained 88.81% of its initial capacitance due to its crosslinking structure.