Search results for "version"
showing 10 items of 1591 documents
Inorganic Protection of Polymer Nanocapsules: A Strategy to Improve the Efficiency of Encapsulated Optically Active Molecules
2018
Bis(oxalato)chromium(III) complexes: Versatile tectons in designing heterometallic coordination compounds
2011
Abstract The mononuclear oxalato-containing chromium(III) complexes of general formula [Cr(AA)(C2O4)2]− (AA = α-diimine type ligand) are able to produce a large variety of heterometallic complexes by acting as ligands towards either fully solvated metal ions or preformed cationic complexes with available coordination sites. This review focuses on the structural diversity of the polynuclear complexes (oligonuclear and coordination polymers) which are generated by the bis(oxalato)chromate(III) species, with a special emphasis to their magnetic properties.
Transport of amino acids through liquid membranes supported on novel poly(vinylidenefluoride) porous flat-sheet matrix
1997
Flat-sheet membranes from poly(vinylidenefluoride) (PVDF) were prepared by the phase inversion process. LiCl was used as a modifying agent. The porosity, maximum pore size and LEPW (liquid entry pressure of water) were determined. Three types of these membranes were tested as a support for n-decanol supported liquid membranes (SLM). Transport of eight amino acids, selected to cover a wide variety of side chains, and of phenylalanine methyl ester through n-decanol SLM were studied. The ability of amino acids to permeates through these membranes depends on the type of flat-sheet PVDF used as a support. An increase in porosity and pore size of the microporous matrix resulted in an increase of …
Functional Nanohybrids Based on Dyes and Upconversion Nanoparticles
2020
Upconversion nanoparticles (UCNPs) and dyes are combined to make nanohybrid systems, which take advantage of the synergic relationship between lanthanide (Ln)-based UCNPs and dyes. Ln-UCNPs are inorganic nanophosphors which absorb NIR light and emit narrow emission bands in the UV-NIR region with long luminescence lifetimes. These unique properties, when coordinated properly with dyes of the appropriate photophysical features, produce nanosystems with new photophysical properties. In this context, the UCNP-dye nanohybrids are very promising for potential sensing (ions and biomolecules) and theragnosis (imaging and therapy, e.g. photodynamic therapy).
Perovskite solar cells prepared by flash evaporation
2015
A simple vacuum deposition method for the preparation of high quality hybrid organic-inorganic methylammonium lead iodide perovskite thin films is reported. When sandwiched in between organic charge transporting layers, such films lead to solar cells with a power conversion efficiency of 12.2%.
Correlation between polymer architecture, mesoscale structure and photovoltaic performance in side-chain-modified poly(p-arylene-ethynylene)-alt-poly…
2011
Abstract Recent investigations have shown that an anthracene containing poly( p -arylene-ethynylene)-alt-poly( p -arylene-vinylene) statistical copolymer consisting of a well defined conjugated backbone, along which linear and branched alkoxy side chains are attached in a random manner, yields, compared to its counterparts with regular side chain substitution, an improved performance in polymer [6,6]:-phenyl-C 61 -butyric acid methyl ester (PCBM) bulk-heterojunction solar cells. The microscopic origin for the improved power conversion efficiency ( η ≈ 3.8%) of the statistical copolymer – which is the best in its material class – has not been resolved. We conducted grazing incidence wide-an…
Antibacterial chitosan-based blends with ethylene–vinyl alcohol copolymer
2010
Abstract This study reports for the first time about the formulation, morphology, water barrier and the antimicrobial activity of high and low molecular weight chitosonium-acetate based solvent-cast blends with ethylene–vinyl alcohol (EVOH) copolymers. The blends based on the low molecular weight chitosan grade showed enhanced phase morphology, transparency, enhanced water barrier properties, up to 86% water permeability reduction compared to pure chitosonium-acetate films, as well as excellent antimicrobial activity. When the fraction of low molecular weight chitosan exceeded the phase inversion in the blend, phase segregation became noticeable but good interfacial adhesion was still obser…
Transmission of mechanical energy through polymeric liquid crystals and their blends
1988
Molecular composites, also called polymeric liquid crystals (PLC), are contrasted with the traditional composites; the name heterogeneous composites is proposed for the latter. Advantages of blending PLCs with ordinary engineering polymers are discussed. Results reported for blends of poly(ethylene terepthalate) (PET) with a PLC containing sequences of PET and p-hydroxybenzoic acid (PHB) include thermophysical properties, melt rheology, mechanical properties of solid blends, and scanning electron microscopy of fracture surfaces. A model called the island model was developed to explain the results: One assumes that the lines of force as well as propagating cracks tend to concentrate in the p…
Metal-Oxide-Free Methylammonium Lead Iodide Perovskite-Based Solar Cells: the Influence of Organic Charge Transport Layers
2014
Metal-oxide-free methylammonium lead iodide perovskite-based solar cells are prepared using a dual-source thermal evaporation method. This method leads to high quality reproducible films with large crystal domain sizes allowing for an in depth study of the effect of perovskite film thickness and the nature of the electron and hole blocking layers on the device performance. The power conversion efficiency increases from 4.7% for a device with only an organic electron blocking layer to almost 15% when an organic hole blocking layer is also employed. In addition to the in depth study on small area cells, larger area cells (approx. 1 cm(-2)) are prepared and exhibit efficiencies in excess of 10…
Chiroptical inversion of a planar chiral redox-switchable rotaxane.
2019
Reversible redox-switching of a planar chiral [2]rotaxane with a tetrathiafulvalene-bearing crown ether macrocycle generates a complete sign reversal of the main band in the ECD spectrum, as shown by experiment and rationalised by DFT calculations.