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Kenneth M. Doll Randal L. Shogren J. L. Willett Graham Swift 《Journal of polymer science. Part A, Polymer chemistry》2006,44(14):4259-4267
Copolymers of citric acid and D ‐sorbitol were synthesized with a solvent‐free vacuum‐oven synthesis with molar ratios of citric acid to D ‐sorbitol ranging from 1/1 to 6/1. The extent of the reaction was followed by the monitoring of the residual acid content of the system. As expected, the reaction occurred much more rapidly at 150 than at 110 °C. The Fourier transform infrared (FTIR) spectra of the products showed the expected FTIR bands at approximately 1735 and 1188 cm?1, which were indicative of ester formation. Gel permeation chromatography showed a major product with a molecular weight of approximately 3500 Da. An insoluble material with a water‐absorption index of up to 17 was also synthesized and could lead to possible applications as absorbers, thickeners, and biobased seed coatings. Additionally, the mono‐ and disodium salts of citric acid were also polymerized with D ‐sorbitol in a manner similar to that of the citric acid system. Soluble polymers were synthesized with a residual acid content of 5 mequiv/g of polymer. These materials showed Ca+2‐sequestering ability (up to 0.56 mmol of Ca+2/g of the product). © 2006 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem 44: 4259–4267, 2006 相似文献
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Raymond JW Gardiner EJ Willett P 《Journal of chemical information and computer sciences》2002,42(2):305-316
Recently a method (RASCAL) for determining graph similarity using a maximum common edge subgraph algorithm has been proposed which has proven to be very efficient when used to calculate the relative similarity of chemical structures represented as graphs. This paper describes heuristics which simplify a RASCAL similarity calculation by taking advantage of certain properties specific to chemical graph representations of molecular structure. These heuristics are shown experimentally to increase the efficiency of the algorithm, especially at more distant values of chemical graph similarity. 相似文献
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The EPR linewidths in [(CH3)2CHNH3]2CuCl4 have been measured at 78 K. The salt contains two types of structurally and magnetically inequivalent chains. Each chain can be visuallized as a narrow ribbon cut from the two dimensional (RNH3)2CuCl4 structures. The EPR g values are consistent with the structural characteristics of each chain. The linewidths are influenced by anisotropic and antisymmetric exchange, and also exhibit low dimensional spin diffusion behavior. The symmetry axis of the diffusional behavior is normal to the plane of the ribbon, implying that the spin correlations in the ribbons are two dimensional in nature. 相似文献