Limin Zang

Preparation and application of conducting polymer/Ag/clay composite nanoparticles formed by in situ UV-induced dispersion polymerization

In this work, composite nanoparticles containing polypyrrole, silver and attapulgite (PPy/Ag/ATP) were prepared via UV-induced dispersion polymerization of pyrrole using ATP clay as a templet and silver nitrate as photoinitiator. The effects of ATP concentration on morphology, structure and electrical conductivity were studied. The obtained composite nanoparticles with an interesting beads-on-a-string morphology can be obtained in a short time (10 min), which indicates the preparation method is facile and feasible. To explore the potential applications of the prepared PPy/Ag/ATP composite nanoparticles, they were served as multifunctional filler and blended with poly(butylene succinate) (PBS) matrix to prepare biodegradable composite material. The distribution of fillers in polymer matrix and the interfacial interaction between fillers and PBS were confirmed by scanning electron microscope, elemental mapping and dynamic mechanical analysis. The well dispersed fillers in PBS matrix impart outstanding antibacterial property to the biodegradable composite material as well as enhanced storage modulus due to Ag nanoparticles and ATP clay. The biodegradable composite material also possesses modest surface resistivity (106 ~ 109 Ω/◻).

Nano-cladding of natural microcrystalline cellulose with conducting polymer: preparation, characterization, and application in energy storage

This study demonstrates the possibility to coat individual fibers of natural microcrystalline cellulose with polypyrrole using in situ chemical polymerization to obtain an electrically conducting continuous high charge storage capability composite with a nano-cladding structure. By manipulating the ordered nano-cladding nanostructure, conducting nanocomposites were achieved and outstanding electrical conductivity, as high as 48.7 S cm−1, was obtained with the feeding mass ratio of sisal microcrystalline cellulose SMC : Py = 3 : 7. X-ray photoelectron spectroscopy (XPS) results showed that with the increase in SMC content, doping level of PPy in the composite increased. It was found that the PPy nanoparticles deposited on the surface of the SMC and connected to form a continuous cladding. The as-prepared SMC/PPy nanocomposites demonstrated a mass-specific capacitance (Cs) of 367 F g−1 at a 0.2 A g−1 current density in the supercapacitor application. Moreover, SMC/PPy electrode retained about 87.5% of the initial Cs after 1000 cycles, and about 57.8% of Cs when the current density increased five times. This study provides a straightforward method to utilize the renewable resource sisal microcrystalline cellulose to obtain a conducting composite, which could be applied in sensors, flexible electrodes, and flexible displays. It also opens a new field of potential applications of micrometre-scale natural microcrystalline cellulose.

Preparation of Functionalized Magnetic Silica Nanospheres for the Cellulase Immobilization

Cellulase was immobilized on functionalized magnetic silica nanospheres using glutaraldehyde as a cross-linking agent. The morphologies, structures and magnetic properties of this immobilized cellulase were characterized by transmission electron microscopy, Fourier transform infrared spectroscopy, thermogravimetric analysis, differential thermal analysis and vibrating sample magnetometry. The properties of immobilized cellulase were investigated, including the amount of immobilized cellulase and its relative activity, stability and reusability. The results indicated that immobilized cellulase exhibited better resistance to high temperature and pH inactivation in comparison to free cellulase. Moreover, immobilized cellulase with and without cross-linking agent were investigated and the former had greater amount of immobilized cellulase and better operational stability. The amount of immobilized cellulase with the cross-linking agent was 92 mg/g support. Furthermore, the activity of the immobilized cellulase was still 85.5% of the initial activity after 10 continuous uses, demonstrating the potential of this immobilized cellulase for large-scale biofuel production.

Structural investigation of anionic functional poly(vinyl alcohol) doped polypyrrole nanospheres

This article reports on a facile route for the preparation of polypyrrole nanospheres with improved water solubility, ordering and conductivity in the presence of a polyelectrolyte, such as phosphorylated polyvinyl alcohol. The phosphorylated polyvinyl alcohol (PPVA) was used as both the stabilizer and the dopant in the chemical oxidative polymerization of pyrrole. The resulting PPVA doped polypyrrole (PPy) nanocomposites (PPy-PPVA) were characterized with FTIR, TGA, SEM and AFM techniques. The electrical conductivity of polymer was measured by four-point probe method. Our observation and results suggest a plausible formation mechanism of PPy nanospheres, PPVA micelle might have functioned as ‘template’ during the polymerization of pyrrole monomers, meanwhile, the PPy chains doped with phosphate group. It was found that the size decreased and their dispersion stability in water increased with the increasing feeding ratio of PPVA. The conductivity of PPy with different morphologies was also measured and compared. When the PPVA: pyrrole feeding ratio ranged from 20 to 50 wt%, the PPy-PPVA nanoparticles showed spherical shape with excellent uniformity, good electrical conductivity (up to 33.1 S·cm−1), and weakly temperature dependent conductivity. It’s worth mentioning that the PPy-PPVA nanocomposite prepared in high PPVA feeding ratio has been well-dispersed for more than 24 months, which indicates its significant dispersion stability.

Preparation and Characterization of Bayberry-Like Polypyrrole Composites Using Functionalized Mesoporous Silica as In Situ Dopant

A series of polypyrrole composites with different content of functionalized mesoporous silica, which functioned as the in situ dopant and inorganic host, were prepared. The morphology, structure, thermal stability, and electrical properties of the samples were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, cyclic voltammetry, and galvanostatic charge-discharge test. The content of functionalized mesoporous silica had strongly impact on the morphology and electrical properties of the samples. When the value was 10 wt%, the sample showed a bayberry-like morphology and possessed the maximum electrical conductivity and specific capacitance of 33.33 S/cm and 237.6 F/g, respectively. GRAPHICAL ABSTRACT