Values of intrinsic viscosity [ζ] measured in 2,2,2‐trifluoroethanol (TFE) and in 1·0M aq. NaCl solution mean square radii of gyration s2z and weight‐average molecular masses Mw measured in TFE at 298 K for 12 well fractionated poly[N‐(3‐sulphopropyl)‐N‐methacrylooxyethyl‐N,N‐dimethylammonium betaine] (PSPE) samples have been used to derive the unperturbed dimensions (
Poly[N-2-(methacryloyloxy)ethyl-N,N-dimethyl-N-3-sulfopropy~ammonium betaine] (1)which is an interesting polyzwitterion polymer by virtue of its "antipolyelectrolyte solution behaviour" has been prepared by free-radical initiated polymerization in aqueous solution.Isothermal fractionation was conducted at 294 K employing formamide as solvent and acetone as precipitant. -Welve fractions covering a wide range of weight-average molecular weight (21 5 OOO 5 M , 5 2070000) were used to characterise the polymer by light scattering, membrane osmometry and viscosity measurements. The Mark-Houwink equations, established for 1 in two good solvents, 2,2,2-trifluoroethanoI (TFE) and 1,0 M aqueous NaCl solution, show that the polymer has a random coil configuration and that TFE is a thermodynamically better solvent than 1 ,O M aqueous NaCl solution. The random coil configuration of 1 in TFE was confirmed from the dependence of the polymer dimensions on molecular weight. 0 1991, Hiithig & Wepf Verlag, Basel CCC 0025-1 16X/91/$05.00
Since the beginning of the 5th century, people felt the urge to construct a sort of heat insulation system to their houses. This research paper focuses on the preparation, development and design of heat insulating tiles using materials like automobile tires powder and rice husk which are materials that are available at almost negligible costs and great amounts. Throughout this paper, experimental work will be provided to document, analyze and compare different insulating materials based on their thermal conductivity factor (K-factor), economic aspects, contribution to a greener earth, and mechanical properties. The results show that a mixture of used automobile tires powder and epoxy has a K factor of 0.0117 W/m°C, and that of a rice husk mixture with epoxy is 0.0118 W/m°C. These values are considerably lower than the K factor of the currently used polyurethane foam (which is 0.026 W/m°C), and therefore these mixtures are more efficient heat insulators than the currently used foam. Calculations have also shown that the manufacture of these mixtures cost 65% less than that of the polyurethane foam.
A simple green one-step method for the synthesis of highly active palladium nanoparticles embedded on copper oxide as an efficient catalyst for ligand-free Heck and Sonogashira cross-coupling reactions has been developed. The synthetic approach is based on Microwave (MW)-assisted simultaneous chemical reduction of an aqueous solution of palladium and copper salts using hydrazine hydrate as the reducing agent. Selected characterization of the catalyst with transmission electron microscope (TEM), X-ray photoelectron spectroscopy (XPS) and X-ray diffraction spectroscopy (XRD) reveal a size range of 25[Formula: see text][Formula: see text][Formula: see text]2[Formula: see text]nm for the generated catalyst nanoparticles with the highest catalytic activity. The use of the generated Pd/CuO nanoparticles is highly advantageous due to the use of ethanol/water as an environmentally green solvent under mild reaction conditions. Furthermore, the synthesized Pd/CuO nanoparticles catalyst can be recycled and re-used up to five times with negligible effect on the efficiency having turnover number up to 6000 and turnover frequency reaching 72[Formula: see text]000[Formula: see text]h[Formula: see text] for 20[Formula: see text]wt.% Pd loaded catalyst at 150∘C.
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