Graphene oxide reinforced poly (vinyl alcohol) nanocomposite: fabrication and characterization for thermal and mechanical properties investigations

We reported the fabrication of poly (vinyl alcohol) incorporated with two different sizes of graphene oxide particles. Scanning electron microscopy (SEM) revealed two sizes of graphene oxide, the first size is as prepared GO_300 nm and the second size is 100nm after hard sonication. The alteration in thermal and mechanical properties of PVA/ GO (5, 10, 15, 20%) nanocomposite compering with PVA are mainly due to the uniform dispersion of GO particles in the polymer matrix and huge interfacial interaction between PVA and GO sheets. Differential scanning calorimetry shows obvious changes in thermal characteristics of PVA after mixing with GO particles. The composite samples exhibit a significant finding at different concentrations and size distribution of GO. First published online 17 April 202

Study on the morphology of polyacrylamide – silica fumed nanocomposite thin films

Silica fumed nanoparticles were dispersed in polyacrylamide thin films by direct mixing. Atomic Force Microscopy study was carried out in order to analyze the surface roughness. Height distribution of surface roughness changes from Gaussian like for polyacrylamide to skew asymmetric when increasing the silica concentration. The length of the distribution tail increases, indicating the formation of multi-scale features that increase in number and size, as the silica increase.The authors acknowledge the financial support of the German research foundation (DFG), French academy of sciences and French Ministry of Foreign Affairs, Prof. Philippe Meyer and the Meyer Foundation

Copper selenide film electrodes prepared by combined electrochemical/chemical bath depositions with high photo-electrochemical conversion efficiency and stability

Copper selenide (of the type Cu2-xSe) film electrodes, prepared by combined electrochemical (ECD) followed by chemical bath deposition (CBD), may yield high photo-electrochemical (PEC) conversion efficiency (~14.6%) with no further treatment. The new ECD/CBD-copper selenide film electrodes show enhanced PEC characteristics and exhibit high stability under PEC conditions, compared to the ECD or the CBD films deposited separately. The electrodes combine the advantages of both ECD-copper selenide electrodes (in terms of good adherence to FTO surface and high surface uniformity) and CBD-copper selenide electrodes (suitable film thickness). Effect of annealing temperature, on the ECD/CBD film electrode composition and efficiency, is discussed.The results of this work are partly based on K. Murtada M.Sc. Thesis, under direct supervision of H.S. Hilal. Other experimental measurements and calculations, including dark current experiments, film thickness measurement, electrical conductivity, SEM analysis, XRD &AFM analysis revisions were performed by A. Zyoud after the thesis completion. Additional film electrode stability experiments under PEC conditions, were also performed by A. Zyoud after the Thesis completion. SEM micrographs and EDX spectra were measured by T.W. Kim and H-J.C. at the KIER, Korea. The XRD patterns were measured by D-H. Park and H. Kwon at PUK. M.H.S. Helal and H. Bsharat contributed with literature search, discussions and modeling. M. Faroun measured AFM micrographs at Al-Quds University. H.S. Hilal acknowledges financial support from ANU, Islamic Development Bank, Al-Maqdisi Project and Union of Arab Universities. T.W. Kim and H-J. Choi acknowledge financial support from the framework of the Research and Development Program of the Korea Institute of Energy Research (B6-2523)

Functional Π-conjugated polymers based on maleimide for photovoltaic applications

A series of new bis-(2-thienyl) maleimide monomers have been synthesized and characterized. The bis-(2thienyl)maleimide unit has been copolymerized with dierent aromatic comonomers. Stille coupling polymerizations under various conditions have been utilized. The copolymers were then characterized by size-exclusion chromatography and their optical and electronic properties were investigated by UV-Vis absorption spectroscopy and cyclic voltammetry. All maleimide based copolymers shared similar LUMO energy levels, which are largely determined by the acceptor moiety, and are close to that of PC61BM to be eective for charge dissociation. These low band gap polymers have been tested for photovoltaic applications and have shown moderate photovoltaic performance. Interesting results were obtained by adding the polymer to the P3HT:PC61BM mixture, as a third component. The ternary blend BHJ solar cells showed power conversion eciencies of 35% exceeding those of the corresponding binary blends

Growth of 2,2-Biimidazole-Based Nanorods on Mica Substrate

The synthesis of a one-dimensional single-stranded helix using the crystallization of silver (I) nitrate and 2,2-biimidazole has promising potential for use in the area of nanotechnology mainly because of its unique electrical properties and its structural similarity to naturally occurring nucleic acids. In this study, we report a new method for the deposition and growth of 2,2-biimidazole-based nanorods on mica substrates by employing a complex solution of silver nitrate (I) and 2,2-biimidazole. The morphology and electrical polarizability of the prepared nanorods are investigated by tapping mode atomic force microscopy (AFM) and noncontact electrostatic force microscopy (EFM). The experimental results show highly polarizable and singly separated nanorods oriented in three preponderant directions. In addition, we show that the active K+ ions on the mica surface are required for the formation of these nanorods. Additionally, these potassium ions are a critical factor in controlling the nucleation and morphology of nanostructures

Preparation and characterization of carvedilol-loaded poly(d,l) lactide nanoparticles/microparticles as a sustained-release system

<p>Carvedilol poly(d,l)-lactide nanoparticles/microparticles were prepared. The size and morphology of the developed particles were optimized to study the carvedilol release profile by studying the effect of organic solvents and polymer amount through atomic force microscopy analysis. Spherical particles were obtained with a minimum size of 125 nm in the case of acetone and a maximum size of 970 nm in the case of dichloromethane affording microparticles formation. The interaction was confirmed by differential scanning calorimeter and Fourier transform infrared. The <i>in vitro</i> release profile of the multicompartment system (pure carvedilol, loaded nanoparticles and microparticles) has shown a sustained release with Korsmeyer–Peppas with T lag model.</p

Functional Π-conjugated polymers based on maleimide for photovoltaic applications

A series of new bis-(2-thienyl) maleimide monomers have been synthesized and characterized. The bis-(2thienyl)maleimide unit has been copolymerized with dierent aromatic comonomers. Stille coupling polymerizations under various conditions have been utilized. The copolymers were then characterized by size-exclusion chromatography and their optical and electronic properties were investigated by UV-Vis absorption spectroscopy and cyclic voltammetry. All maleimide based copolymers shared similar LUMO energy levels, which are largely determined by the acceptor moiety, and are close to that of PC61BM to be eective for charge dissociation. These low band gap polymers have been tested for photovoltaic applications and have shown moderate photovoltaic performance. Interesting results were obtained by adding the polymer to the P3HT:PC61BM mixture, as a third component. The ternary blend BHJ solar cells showed power conversion eciencies of 35% exceeding those of the corresponding binary blends

Enhancement of CdSe film electrode PEC characteristics by metalloporphyrin/polysiloxane matrices

A facile and low-cost strategy to improve stability and conversion efficiency of CdSe film electrodes prepared by chemical bath deposition (CBD) onto FTO/glass substrates, is described. The naked CdSe film electrodes, with band gap value 1.8 eV, photo-corroded under the photoelectrochemical (PEC) working conditions and exhibited no photocurrent. The CdSe film peeled out in short times. Attempts made to enhance stability and efficiency of naked CdSe electrodes, by chemical etching or pre-scratching the FTO surface with fine sand-paper, failed to improve film PEC characteristics. Annealing the glass/FTO/CdSe film also failed to improve its PEC stability or efficiency. When coated with the electro-active species Tetra(-4-pyridyl)porphyrinatomanganeseIII/II sulfate embedded inside polysiloxane films (MnPyP/Polysil) the CdSe films did not peel out under the PEC conditions. The coated electrode (glass/FTO/CdSe/MnPyP/Polysil) clearly exhibited photocurrents. Pre-annealing the naked CdSe film at 350 °C, followed by coating with MnPyP/Polysil further enhanced the electrode PEC characteristics. Additional heating of the prepared glass/FTO/CdSe/MnPyP/Polysil electrode at 120 °C also enhanced its PEC characteristics. The mode of action of the MnPyP/Polysil coating has been attributed to its ability to behave as a charge transfer catalyst at the solid/liquid interface. The new technique described here could also be potentially valuable for other types of thin film electrode materials