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Complex Polymer (complex + polymer)
Selected AbstractsTwo-Dimensional Chromatography of Complex Polymers, 7 , Detailed Study of Polystyrene- block -Polyisoprene Diblock Copolymers Prepared by Sequential Anionic Polymerization and Coupling ChemistryMACROMOLECULAR CHEMISTRY AND PHYSICS, Issue 19 2008Valentina Mass Abstract Two-dimensional chromatographic methods were developed using LC-CC in the first and SEC in the second dimension. These methods were applied for the investigation of PS- b -PI diblock copolymers synthesized by different approaches: sequential living anionic polymerization and coupling of living precursor blocks. The first dimension separates according to the individual block length of PS or PI blocks, whereas the second dimension separates with respect to the total molar masses of components. 2D-LC analysis provides information on the purity of the reaction products, the presence of by-products, the chemical compositions and the molar masses of all product components. The accuracy and selectivity of 2D-LC is discussed. [source] THE COST OF MELANIZATION: BUTTERFLY WING COLORATION UNDERENVIRONMENTAL STRESSEVOLUTION, Issue 2 2004W. Talloen Abstract Evolutionary studies typically focus on adaptations to particular environmental conditions, thereby often ignoring the role of possible constraints. Here we focus on the case of variation in dorsal wing melanization in a satyrine butterfly Pararge aegeria. Because melanin is a complex polymer, its synthesis may be constrained if ambient conditions limit the resource budget. This hypothesis was tested by comparing melanization among butterflies that fed as larvae on host grasses experiencing different drought-stress treatments. Treatment differences were validated both at the level of the host plant (nitrogen, carbonate, and water content) and of the butterfly (life-history traits: survival, development time, and size at maturity). Melanization rate was measured as average gray value of the basal dorsal wing area. This area, close to the thorax, is known to be functionally significant for basking in order to thermoregulate. Individuals reared on drought-stressed host plants developed paler wings, and development of darker individuals was slower and less stable as estimated by their level of fluctuating asymmetry. These results provide evidence that melanin is indeed costly to synthesize, and that differences in environmental quality can induce phenotypic variation in wing melanization. Therefore, studies dealing with spatial and/or temporal patterns of variation in wing melanization should not focus on adaptive explanations alone, but rather on a cost-benefit balance under particular sets of environmental conditions. [source] Electrogenerated chemiluminescence of ruthenium complex immobilized in a highly cross-linked polymer and its analytical applicationsLUMINESCENCE: THE JOURNAL OF BIOLOGICAL AND CHEMICAL LUMINESCENCE, Issue 6 2008Lihua Shen Abstract Electrogenerated chemiluminescence (ECL) of a ruthenium complex polymer modified carbon paste electrode and its analytical applications were investigated. The ruthenium complex polymer was prepared using bis(2,2-bipyridine) (4,4-dicarboxy-2,2-bipyridine) ruthenium(II). The ECL behaviours of ruthenium complex polymer modified carbon paste electrode were investigated in the absence and presence of tripropylamine (TPA). The modified carbon paste electrode exhibited long-term stability and fine reproducibility. The ECL intensity of the modified carbon paste electrode was linear with the concentration of TPA in the range 2.0 × 10,6,3.8 × 10,3 mol/L, with a detection limit (S:N = 3) of 6 × 10,7 mol/L. It was also found that raceanisodamine could enhance the ECL intensity of the modified electrode. The ECL intensity of the modified carbon paste electrode was linear with the concentration of raceanisodamine in the range 1.1 × 10,5,6.0 × 10,4 mol/L, with a detection limit (S:N = 3) of 6 × 10,6 mol/L. This work demonstrates that the entrapment of ruthenium complex in a highly cross-linked polymer is a promising approach to construct an ECL modified electrode with long-term stability and fine reproducibility. The modified electrode designed has a potential application in the ECL detector. Copyright © 2008 John Wiley & Sons, Ltd. [source] Simple Determination of Segment Numbers for Complex Polymer-Solvent SystemsCHEMICAL ENGINEERING & TECHNOLOGY (CET), Issue 2 2007S. Machefer Abstract A theoretical analysis was made to show that segment numbers for complex polymers can be determined by interpreting pVT data in terms of an appropriate segment-based equation of state (EOS). Typically, experiments at high pressures have to be performed to obtain these data. In this study, pVT-derived properties, such as compressibility and speed of sound, together with isobaric specific volume measurements were used as an alternative data source. Experiments were carried out for polyol/water mixtures of different compositions. Taking account of the polymorphism of water, segment numbers were obtained by a numerical regression analysis. Mixture viscosities were calculated using an approved segment-based mixing rule and were in good agreement with experimental data over the temperature range of interest, indicating the validity of the determined segment numbers. [source] Description of the Structure and Properties of Atactic Polystyrene Melt Using Integral Equation TheoryCHINESE JOURNAL OF CHEMISTRY, Issue 12 2007Lei ZHAO Abstract The polymer reference interaction site model (PRISM) integral equation theory was used to describe the structure and thermodynamic properties of atactic polystyrene (aPS) melt, in which the monomer of aPS is represented with an eight-site model to characterize its microstructure. The intramolecular structure factors needed in the PRISM calculations were obtained from single chain MD simulations. The calculated results indicate that the results by the integral equation method agrees well with experiments, and can reflect the fine microscopic structure of real aPS melt. This work shows that the PRISM theory is a powerful tool for investigating the structure and properties of complex polymers. [source] | ||||||||||