Electrospun polymer nanofibers: the booming cutting edge technology

Electrospinning has been recognized as a simple and efficient technique for the fabrication of ultrathin fibers from a variety of materials including polymers, composite and ceramics. Significant progress has been made throughout the past years in electrospinning and the resulting fibrous structures have been exploited in a wide range of potential applications. This article reviews the state-of-art of electrospinning to prepare fibrous electrode materials and polymer electrolytes based on electrospun membranes in the view of their physical and electrochemical properties for the application in lithium batteries. The review covers the electrospinning process, the governing parameters and their influence on fiber or membrane morphology. After a brief discussion of some potential applications associated with the remarkable features of electrospun membranes, we highlight the exploitation of this cutting edge technology in lithium batteries. Finally the article is concluded with some personal perspectives on the future directions in the fascinating field of energy storag

Liquid crystal micro-lenticular array assembled by a fringing field

Based on dielectrophoretic effect, the phase separation morphology of liquid crystal ( LC) in a liquid monomer can be manipulated by a fringing field. Applying the fringing field generated from interdigitated electrode upon the LC/monomer mixture, the randomly dispersed LC droplets can be assembled to grating-like stripes. When the field is removed, the LC stripes break into tiny droplets again. This process is reversible and stable. Our results show that the surface profile of each LC stripe exhibits a lenticular shape. The response time of the LC morphology converting from droplets to stripes and from stripes to droplets is similar to 0.96 s. Potential applications of this controllable morphology can be found in optical communications, beam steering, imaging, and displays

Carbon nanotube-reinforced elastomeric nanocomposites: a review

This review is focused on carbon nanotube (CNT)-elastomeric polymer nanocomposites, which have attracted industrial and academic interest over the years due to their enhanced properties. Major factors notably CNT type, surface modification, dispersion of CNT, and processing techniques that affect the physical properties of CNT-elastomeric polymer nanocomposites are reviewed, and several key physical properties, including tensile, electrical, and thermal properties, were also included in this review. Some of the key challenges that undermine the effectiveness of CNTs and their composites with elastomeric polymers, and the potential applications of CNT-elastomeric composites are also captured

Free-Standing and Circular-Polarizing Chirophotonic Crystal Reflectors: Photopolymerization of Helical Nanostructures

The preparation of materials exhibiting structural colors has been intensively studied in biomimetic science and technology. Utilizing a newly synthesized cholesteric liquid-crystal (CLC) monomer (abbreviated as BP₁CRM), we have prepared CLC films. Photoinitiated copolymerization of this monomer with a common achiral liquid-crystalline monomer produced free-standing films with homogeneous and nanoscale pitch distributions. Employing the thermal sensitivity of the CLC monomer, chirophotonic crystal reflectors were prepared exhibiting a range of colors. The free-standing and circular-polarizing chirophotonic crystal films maintain excellent thermal, mechanical, and chemical stabilities, and the composition can readily be applied as polarized optical films and smart paints

Three-dimensional actuators transformed from the programmed two-dimensional structures via bending, twisting and folding mechanisms

Combining the physical principle of actuators with the basic concept of photonic crystals, colour-tunable three-dimensional (3D) photonic actuators were successfully fabricated. By controlling the d-spacings and the refractive index contrasts of the self-assembled 3D colloidal photonic crystals, colours of the photonic actuators were tuned. Various shapes of these 3D actuating objects were constructed by transforming the programmed 2D structures via bending, twisting and folding mechanisms. These 2D structures were first programmed by breaking the symmetry. The selective swellings were then applied as driving forces to control the shapes and colours of the photonic actuators. Scroll photonic actuators had been first demonstrated by bending the traditional 2D cantilever structure (K.-U. Jeong, et al., J. Mater. Chem., 2009, 19, 1956). By breaking the symmetry of a cantilever structure perpendicular to its long axis, polypeptide-/DNA-like 3D helical photonic actuators were obtained from the programmed 2D structure via twisting processes. Both left-and right-handed scrolls and helices with various colours can be achieved by changing the polarity of solvents. Different types of 3D actuators, such as cube, pyramid and phlat ball, were also demonstrated via the folding mechanism. The reversible 3D photonic actuators transformed from the programmed 2D structures via the bending, twisting and folding mechanisms may be applied in the field of mechanical actuators, and optoelectronic and bio-mimetic devices.close221

Electrodeposited Binder-free Mn-Co‑S Nanosheets toward High Specific-Energy Aqueous Asymmetric Supercapacitors

A simple single-step electrodeposition technique was followed for the three-dimensional (3D)-interconnected binary metallic manganese-cobalt sulfide nanosheets on nickel foam (MnCoS@NF). The architecture and chemical composition of the as-synthesized binder-free electrodes were analyzed by field-emission scanning electron microscopy (FESEM), high-resolution transmission electron microscopy (HRTEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The MnCoS@NF achieves exceptionally high specific capacitance (1952.8 F g–1 at 2 A g–1) along with high cycle stability in a three-electrode cell measurement. Furthermore, an aqueous asymmetric supercapacitor (AAS) device was designed using electrodeposited MnCoS@NF in combination with reduced graphene oxide-coated NF (rGO@NF) as a positrode and negatrode, respectively. This device was able to provide very high specific energy (105.1 W h kg–1) at a specific power (7.25 kW kg–1) along with high cyclic stability (93.9% of specific capacitance retained after 3000 consecutive GCD cycles), which demonstrates its excellent candidature in supercapacitor applications

Colour-tunable spiral photonic actuators

Combining the multi-faceted environmental responsiveness of polymers with photonically active structures, we developed spiral photonic actuators which can reversibly change both shape and colour in response to the chemical environment.close131

PDMS-ZnSnO₃/Ag₂O‑Based Nanocomposites for Mechanical Energy Harvesting and Antibacterial Applications

Bacterial fouling of self-powered implantable devices poses severe concerns for device implantation in the human body or water system installation. Here, a piezocomposite based on polydimethylsiloxane-zinc stannate/silver oxide (PDMS-ZnSnO3/Ag2O) has been fabricated and studied for its mechanical energy harvesting capability, as well as its antibacterial activity toward the Pseudomonas aeruginosa bacterium model. The surface decoration of n-type ZnSnO3 nanocubes with p-type Ag2O made an effective bulk p–n heterojunction, which augmented its energy harvesting and biological activities. The maximum output voltage, current, and power density of the fabricated piezoelectric nanogenerator (PENG) are ∼36 V, ∼1.9 μA, and ∼11.4 μW/cm2, respectively, under finger tapping. The enhanced energy harvesting property has been well explained by the high piezoelectric coefficient of modified nanoparticles obtained from the piezoresponse force microscopy (PFM) study. Moreover, the energy conversion efficiency of the PENG estimated during capacitor (10 μF) charging is ∼2.49%. Moreover, a Gram-negative bacterium model is chosen for the biofilm formation study. Biofilm assay, antimetabolite, and intracellular reactive oxygen species (ROS) studies reveal that the piezocomposite containing ZnSnO3/Ag2O is an excellent material for antibacterial activities. Thus, this work has proposed the idea of utilizing an electron-screen-enabled antibacterial piezocomposite, which could efficiently harvest human motion/blue energy incessantly with a specially designed electrode