Wrap‐around electrodes for microLED tiled displays

The authors have developed a process to create wrap‐around electrodes (WAEs) on glass for use in tiled microLED display applications. The electrodes have small size and spacing, low resistance, and good reliability. In addition, an opaque overcoat protects the edges of the tiles and reduces seam visibility. These electrodes allow bezel‐free tiled operation for high‐resolution displays.     

Preparation of High‐Performance Conductive Polymer Fibers through Morphological Control of Networks Formed by Nanofillers

A general method is described to prepare high‐performance conductive polymer fibers or tapes. In this method, bicomponent tapes/fibers containing two layers of conductive polymer composites (CPCs) filled with multiwall carbon nanotubes (MWNT) or carbon black (CB) based on a lower‐melting‐temperature polymer and an unfilled polymer core with higher melting temperature are fabricated by a melt‐based process. Morphological control of the conductive network formed by nanofillers is realized by solid‐state drawing and annealing. Information on the morphological and electrical change of the highly oriented conductive nanofiller network in CPC bicomponent tapes during relaxation, melting, and crystallization of the polymer matrix is reported for the first time. The conductivity of these polypropylene tapes can be as high as 275 S m^?1 with tensile strengths of around 500 MPa. To the best of the authors' knowledge, it is the most conductive, high‐strength polymer fiber produced by melt‐processing reported in literature, despite the fact that only ～5 wt.% of MWNTs are used in the outer layers of the tape and the overall MWNT content in the bicomponent tape can be much lower (typically ～0.5 wt.%). Their applications could include sensing, smart textiles, electrodes for flexible solar cells, and electromagnetic interference (EMI) shielding. Furthermore, a modeling approach was used to study the relaxation process of highly oriented conductive networks formed by carbon nanofillers.     

Crystallization of poly(ε-caprolactone)/MWCNT composites: A combined SAXS/WAXS,electrical and thermal conductivity study

In situ crystallization of poly(ε-caprolactone) (PCL) filled with different contents (0.2–5 wt%) of multiwalled carbon nanotubes (MWCNTs) was investigated in X-ray (SAXS/WAXS) synchrotron experiments simultaneously with thermal and electric conductivity measurements. The combined study provides information on nucleation ability of MWCNT, crystallization and melting kinetics, degree of crystallinity as well as the evolution of thermal diffusivity and electrical conductivity of PCL/MWCNT composites during isothermal and non-isothermal crystallization.     

On the Friction of Carbon Black- and Silica-Reinforced BR and S-SBR Elastomers

Friction of carbon black- and silica-reinforced elastomers is studied experimentally and theoretically, using Persson’s model. The effect of reinforcement fillers on elasticity was determined by dynamical mechanical analysis. Carbon black-filled samples have a higher Young’s modulus than the silica-filled compounds. Silica-filled rubbers have a higher tan (δ) at lower temperatures and a lower loss tangent at higher temperatures, which is a rough indication for higher wet grip and lower rolling resistance, respectively. Friction tests on a ball-on-disk test rig were performed to study the effect of the reinforcement fillers and their amount on the friction between rubber samples (disks) and relatively smooth or rough granite surfaces (balls). The results were discussed and compared with the friction model presented by Persson. It was shown theoretically and experimentally that hysteresis does not play a significant role in the friction of rubber samples in contact with smooth granite and that it plays a minor role in contact with a rough granite sphere. Therefore, the hysteresis contribution of friction can be neglected in the contact of rubbers with just smooth spheres. Moreover, a higher friction coefficient is seen in samples with a higher content of fillers. Silica-filled compounds show a slightly higher coefficient of friction compared with the carbon black-filled compounds. The effect of attached wear debris to the granite surfaces on the friction level has been studied. The results are supported by SEM and confocal microscopic images of the wear debris itself and wear debris attached to the granite spheres, respectively.     

Optical absorption,induced bleaching,and photoluminescence of CdSe nanoplatelets grown in cadmium octanoate matrix

CdSe nanoparticles (NPs) are chemically synthesized in thermotropic ionic liquid crystalline (LC) phase of cadmium octanoate that was used as a nanoreactor. The nanocomposite samples are obtained by the rapid cooling of the LC phase to room temperature. Observed doublet structure in absorption spectra of the nanocomposites is characteristic for the two-dimensional CdSe nanoplatelets (NPLs). The thicknesses of the CdSe NPLs are 1.6, 1.9 and 2.3 nm as determined from the absorption spectra, and correspond to 4, 5 and 6 CdSe monolayers, respectively. Induced simultaneous bleaching of the doublet components observed under femtosecond laser excitation, as well as photoluminescence spectra and their kinetics are found compatible with the model of excitons with heavy- and light-hole valence bands confined in nanoplatelets.