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Versatile Material (versatile + material)

Distribution by Scientific Domains

Polymers and Materials Science	40%
Chemistry	40%

Selected Abstracts

Energy Collection, Transport, and Trapping by a Supramolecular Organization of Dyes in Hexagonal Zeolite Nanocrystals,

ADVANCED FUNCTIONAL MATERIALS, Issue 2 2006
C. Minkowski
Abstract The incorporation of guest molecules into the cavities of molecular sieves leads to a large variety of highly interesting materials. Zeolite,L,an aluminosilicate with one-dimensional channels of open diameter 7.1,Å,is a very versatile material for building highly organized host,guest systems. We present materials where organic dye molecules have been incorporated into the channels of zeolite,L by means of diffusion, to build artificial photonic antenna systems. The channel entrance can be plugged by adding closure molecules that then connect the guest molecules inside with materials or molecules outside of the zeolite channels, since they can act as extensions of the interior of the zeolite crystal. The photophysical processes taking place in such dye-loaded zeolite,L antennae can be studied either on single-micrometer- or submicrometer-sized crystals or on crystals dispersed in a solvent or coated as thin layers on a support. The energy-transfer process occurring is of the Förster-type, and its transfer rate can be tuned by separating the donor dyes and the acceptor dyes locally by varying amounts of spacer molecules. The distribution of the dye molecules and empty sites within a zeolite crystal has been modeled by means of a Monte Carlo simulation. The Förster energy migration and transfer steps are described as a random walk. [source]

An investigation into the swelling properties, dimensional changes, and gel layer evolution in chitosan tablets undergoing hydration

ADVANCES IN POLYMER TECHNOLOGY, Issue 1 2009
Manuel Efentakis
Abstract The purpose of this research is to determine several characteristics of chitosan lactate in tablet form such as dimensional changes, gel evolution, swelling (liquid uptake), and erosion using an image analysis method. The examination of these characteristics will be helpful in the design of oral drug delivery systems with this polymer. It has been demonstrated that image analysis is a valuable technique, allowing the study of quantitative measurements of dimensional and core changes and gel evolution. The dimensional expansion changes of the chitosan lactate tablets were greater in water, and the crushing strength and the stirring effect affected these attributes to a limited extent. The fastest and greatest liquid uptake was observed in water, whereas the greatest erosion was observed in HCl. The thickness of the gel layer increased considerably with time up to the eighth hour, indicating the formation and development of a thick and durable gel, particularly in water. This is an essential characteristic for potential sustained drug release delivery. Consequently, this polymer appears to be a versatile material and a promising vehicle for the preparation of various oral sustained release medications and relevant devices. © 2009 Wiley Periodicals, Inc. Adv Polym Techn 28:32,39, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/adv.20147 [source]

Poly(triarylamine): Its synthesis, properties, and blend with polyfluorene for white-light electroluminescence

JOURNAL OF POLYMER SCIENCE (IN TWO SECTIONS), Issue 9 2007
Hung-Yi Lin
Abstract A new high-molecular-weight poly(triarylamine), poly[di(1-naphthyl)-4-anisylamine] (PDNAA), was successfully synthesized by oxidative coupling polymerization from di(1-naphthyl)-4-anisylamine (DNAA) with FeCl3 as an oxidant. PDNAA was readily soluble in common organic solvents and could be processed into freestanding films with high thermal decomposition and softening temperatures. Cyclic voltammograms of DNAA and PDNAA exhibited reversible oxidative redox couples at the potentials of 0.85 and 0.85 V, respectively, because of the oxidation of the main-chain triarylamine unit. This suggested that PDNAA is a hole-transporting material with an estimated HOMO level of 5.19 eV. The absorption maximum of a PDNAA film appeared at 370 nm, with an estimated band gap of 2.86 eV from the absorption edge. Unusual multiple photoluminescence maxima were observed at 546 nm, and this suggested its potential application in white-light-emission devices. Nearly white-light-emission devices could be obtained with either a bilayer-structure approach {indium tin oxide/poly(ethylenedioxythiophene):poly(styrene sulfonate)/PDNAA/poly[2,7-(9,9-dihexylfluorene)] (PF)/Ca} or a polymer-blend approach (PF/PDNAA = 95:5). The luminance yield and maximum external quantum efficiency of the light-emitting diode with the PF/PDNAA blend as the emissive layer were 1.29 cd/A and 0.71%, respectively, and were significantly higher than those of the homopolymer. This study suggests that the PDNAA is a versatile material for electronic and optoelectronic applications. © 2007 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 45: 1727,1736, 2007 [source]

Enhanced control of porous silicon morphology from macropore to mesopore formation

PHYSICA STATUS SOLIDI (A) APPLICATIONS AND MATERIALS SCIENCE, Issue 8 2005
Huimin Ouyang
Abstract Porous silicon (PSi) is a versatile material that possesses a wide range of morphologies. There are two main types of microstructures that are widely used and well studied: branchy mesoporous silicon with pore sizes from 10 nm to 50 nm and classical macroporous silicon with pore sizes from 500 nm to 20 µm. Much less work has been done on structures with intermediate pore sizes from 100 nm to 300 nm. Applications such as immunoassays biosensing can greatly benefit from the intermediate morphology due to the larger pore openings compared to mesopores, and increased internal surface compared to classical macropores. In this work we demonstrate well-defined macropore of 150 nm diameter in average and precise control of the porous silicon morphology transition from smooth macropores to branchy mesopores on one substrate with one electrolyte. A multilayer structure (microcavity) consisting of both mesopores and macropores is presented. (© 2005 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source]

Synthesis of Polysubstituted 3-Iodopyrans by Electrophilic Cyclization

EUROPEAN JOURNAL OF ORGANIC CHEMISTRY, Issue 14 2009
Yong-Xin Xie
Abstract A variety of polysubstituted 3-iodopyrans were readily prepared in good to excellent yield under mild reaction conditions by the reaction of alkynyl carboxamides with ICl, I2, and NIS. The products obtained from this process are versatile materials that can be used to construct other complex functionalized pyran structures of importance. The occurrence of the pyranyl group in both natural products and pharmaceuticals confers important value to this study. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2009) [source]