Oriented PAN/PVDF/PAN laminated nanofiber separator for lithium-ion batteries

Electrospun nanofiber separators have excellent properties in terms of large surface area and high porosity, which benefits the rate capability, electrochemical stability, and safety performance of lithium-ion batteries. Herein, a 0°PAN/PVDF/90°PAN-oriented composite nanofiber separator is prepared, which is prepared layer by layer by electrospinning technology and drum orientation collector. The results show that when the rotating speed of the drum is 600 r min−1, the 0°PAN/PVDF/90°PAN-oriented composite nanofiber separator has high porosity (about 85%), improved transverse and longitudinal tensile properties (10.33 MPa and 11.03 MPa, respectively), good dimensional stability at 160°C, and good electrochemical performance (specific charge capacity of 165 mAh g−1 at 0.5C and 142.7 mAh g−1 at 1C, capacity retention of 90% after 100 cycles).

Dual-Layer Approach toward Self-Healing and Self-Cleaning Polyurethane Thermosets

There is an urgent need for coatings that exhibit both self-healing as well as self-cleaning properties as they can be used for a wide range of applications. Herein we report a novel approach toward fabricating polyurethane thermosets possessing both self-cleaning and self-healing properties. The desired coating was achieved via casting a bottom layer of self-healable polyurethanes comprised of reversible phenolic urethane bonds followed by a subsequent dip-coating of the prepared layer in a solution of bis(3-aminopropyl)-terminated polydimethylsiloxane (PDMS-NH2). The PDMS was used to impart self-cleaning properties to the coating. While the self-healing behavior of the bottom polyurethane layer is achieved through phenolic urethane chemistry, via the exchange of phenolic urethane moieties. The prepared coatings were tested for their optical, mechanical, self-healing, and self-cleaning properties using a variety of characterization methods, which confirmed the successful fabrication of novel self-cleaning and self-healing clear urethane coatings.

Air permeability of nanofiber membrane with hierarchical structure

Air permeability is crucial to nanofibrous membrane applications, such as in wound dressing and membrane distillation. Herein, hierarchical structure membrane is prepared layer by layer with different fiber diameters, using electrospinning method. The results showed that with different layer arrangement results in different air permeability, and optimal condition is found.

Organic-Inorganic Solar Cell Based on Sprayed MEH-PPV/ZnO Nanorods Layers

Zinc oxide layer have been prepared by spray pyrolysis technique. The effect of substrate temperature on structural and optical properties of the prepared layer has been investigated. XRD patterns show that ZnO layers are polycrystalline with (002) plane as preferential orientation. FESM images show that ZnO layeres consist of nanorods. Semi-conducting MEH-PPV polymer, which prepared in our lab, was dissolved in THF and sprayed on glass and KBr substrates at 150 oC with two different carrier gases. Organic-inorganic solar cell from MEH-PPV with ZnO nanorods layers was constructed, characterized and its efficiency was calculated.

Electrochemical Behavior of S-Doped Nanostructured TiO2 Layer Synthesized with PEO Process for Photocatalytic Applications

Sulfur doped and pure micro-nanoporous TiO2 film were synthesized with PEO method to produce a film with a high surface area for photocatalysis applications. The effect of applied voltage and electrolyte concentration on the microstructure and photocatalytic properties of the prepared layer were investigated via SEM, XRD, EIS and DRS studies. Electrochemical Impedance Spectroscopy (EIS) was carried out in order to determine the corrosion and electrochemical properties of the produced layer. It was found that although the barrier layer resistance decreases with the voltage, the layers porosity and consequently the surface area increases. Finally the XRD and DRS spectrums were correlated with corrosion and photocatalytic properties in order to find out the optimum parameters of the PEO process to synthesize a layer with desired Properties.

Characterization of Dislocations in GaAs Grown on Si and Ge

ABSTRACTDislocations are produced at the interface between epilayers and the substrate when there is a lattice mismatch. When GaAs is grown on Ge substrates, these dislocations can propagate into the epilayers. They can then interact with one another or with antiphase boundaries which are generated when the polar-material is grown on a non-polar materials.The interactions between these defects have been investigated using the weak-beam imaging technique of transmission electron microscopy. Possible interactions between the misfit dislocations and heterojunctions were examined in a specially prepared layer structure model of GaAs-AlxGal−xAs.