Biao Wang

Preparation and Properties of Polystyrene/Bacterial Cellulose Nanocomposites by In Situ Polymerization

Polystyrene/bacterial cellulose (PS/BC) nanocomposites were prepared via in situ polymerization. Scanning electron microscopy (SEM), Fourier-transform infrared spectroscopy (FTIR), themogravimetry (TG), and mechanical testing were employed to characterize the PS/BC nanocomposites. The polystyrene filled in the network of the BC and a lamellar structure was formed. The FTIR results show that no chemical reaction between PS and BC occurred during the polymerization. These composites showed good mechanical properties.

Color-tunable luminescent CdTe quantum dot membranes based on bacterial cellulose (BC) and application in ion detection

Color-tunable luminescent membranes of CdTe QDs on bacterial cellulose (BC) nanofibers were successfully fabricated by in situ synthesis in aqueous solution. No nitrogen protection and expensive reagents are needed during the preparation process. The luminescent color of the CdTe/BC nanocomposite membranes with green, orange and red luminescence can be tuned easily by controlling the reaction time. The prepared CdTe/BC nanocomposites were characterized by X-ray diffraction (XRD), field effect scanning electron microscopy with energy dispersive X-ray analysis (FESEM-EDX) and transmission electron microscopy (TEM). Ultraviolet-visible (UV-vis), photoluminescence (PL) spectra and PL quantum efficiency (PL QE) were used to investigate the optical properties. Moreover, we attempted to make the luminescent membranes into an ion test paper. The green luminescent membranes had a good selectivity for Cu2+ with a detection limit of 0.016 mM and the mechanism of quenching Cu2+ were also explored. This work provides a simple, effective and eco-friendly method for the construction of luminescent CdTe QDs on BC membranes with high detectability for detection of Cu2+.

Effects of Stabilization Temperature on Structures and Properties of Polyacrylonitrile (PAN)-Based Stabilized Electrospun Nanofiber Mats

An improved heat treatment strategy for electrospun polyacrylonitrile (PAN)-based nanofiber mats is developed. Polyacrylonitrile nanofiber mats were fabricated by electrospining and then were stabilized at different temperatures. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), X-ray diffraction (XRD), and mechanical testing were used to study the effects of temperature (for times of 1 h) on the structures and properties of PAN-based heat stabilized electrospun nanofiber mats. Results showed that at temperature below 250°C, the structure conversion of PAN nanofibers was not obvious. However, when the stabilization temperature was above 260°C, PAN nanofibers became thermally stable and the aromatization indices increased rapidly to 55.8%, which is preferable for stabilized PAN nanofiber mats. After thermal treatment up to 270°C, most of the C≡N groups in PAN macromolecules change to C˭N groups, implying that the cycling reaction was almost complete at 270°C. The tensile strength of the nanofiber mats revealed that for the highest mechanical properties of the nanofiber mats, the stabilization temperature should be around 260°C.

In situ polymerization and characterization of graphite nanoplatelet/poly(ethylene terephthalate) nanocomposites for construction of melt-spun fibers

A set of novel nanocomposites based on graphite nanoplatelets (GnP) and poly(ethylene terephthalate) (PET) were synthesized using an in situ polymerization approach that were subsequently being spun into fibers on a melt spinning apparatus. The GnP/PET nanocomposites with a filler weight fraction below 2% showed a homogenous fractured surface as a result of good dispersion of GnP in the PET matrix through preliminary dispersant treatment coupled with subsequent melt compounding during the polymerization. Compared to unmodified PET, the GnP/PET nanocomposites were confirmed to improve thermal stabilities and increase crystallization rates which were capable of facilitating the downstream procedure of melt spinning. At a low level of GnP loading, the PET matrix nanocomposite fibers were readily melt-spun without detecting fiber breakage or filament defect and exhibited mechanical properties similar to unmodified PET fiber as the compact interaction was formed between GnP and PET matrix. Particularly, the volume resistivity of the resultant nanocomposite fibers was found to be substantially reduced due to the intrinsic electrical conductivity that the GnP imparts as a filler. Taken together, our work introduces a simple and environmentally friendly method for melt spinning of GnP/PET nanocomposite fibers with great potential for applications in antistatic textile and military industries.

Photocatalytic Properties of Zr-Doped TiO2 Fabrics Prepared by a Template Method

Viscose fabrics were used as templates to prepare bare and Zr-doped TiO2 fabrics. The samples were characterized by X-ray diffractrometer, scanning electron microscope, energy dispersive spectrometry, and UV-vis/diffuse absorption, while the photocatalytic efficiency was evaluated using methylene blue (MB) as the model compound. The samples exhibit the same tricot configuration as the templates and show good catalytic efficiency. Small amounts of Zr doping favored the light adsorption of these fabrics. The doped Zr shifted the beginning of the anatase-to-rutile transformation temperature and suppressed the crystal growth of TiO2. The 18 wt% Zr-doped TiO2 fabrics exhibited the highest efficiency of MB degradation among the samples.

In situ synthesis of carbon fiber-supported SiOx as anode materials for lithium ion batteries

The carbon fiber-supported SiOx (CF–SiOx) composites are in situ fabricated using a facile two-step method and evaluated as anodes for lithium-ion batteries (LIBs). The CF–SiOx anodes exhibit a reversible capacity of 1100 mA h g−1 at 50 mA g−1 after a high current charge–discharge cycling test with a capacity retention of 80% (compared with the first 5 cycles). This superior performance of the CF–SiOx are due to the modification of SiOx with the profiled carbon fibers, which effectively construct a continuous conducting network and thus enhance the electrochemical activity of SiOx. The profiled carbon fibers have numerous surface grooves to provide high contact area for rapid lithium-ion transport and enough inter-fiber space for the accommodation of large SiOx volume changes on lithium insertion and extraction.