The Experts below are selected from a list of 282 Experts worldwide ranked by ideXlab platform
Sandra C. Greer - One of the best experts on this subject based on the ideXlab platform.
-
Partitioning of Poly(ethylene oxide), Poly(ethylene imide), and Bovine Serum Albumin in Isobutyric Acid + Water
Macromolecules, 2008Co-Authors: Alexander I Norman, Brittney A Manvilla, Evan L Frank, Justine N Niamke, Grant D. Smith, Sandra C. GreerAbstract:We present new measurements of the partitioning of the polymers (poly(ethylene glycol) (PEG) and poly(ethylene imine) (PEI)) and the protein bovine serum albumin (BSA) between coexisting Liquid Phases of isobutyric acid + water. We show that all partition unevenly between the Liquid Phases: In all cases, there is substantially more polymer or protein in the upper, isobutyric acid-rich phase. At molecular masses above about 10 kg/mol, PEG and PEI fractionate between the Liquid Phases, with a higher average molecular mass in the lower, water-rich phase. The fractionation and partitioning are amplified both when the molecular mass of the polymer is increased, and when D2O + isobutyric acid is used instead of H2O + isobutyric acid. The dependence of the distribution coefficient on molecular mass disagrees with the predictions of Flory−Huggins mean field theory for all PEG and PEI systems studied. At low molecular weight, the PEG fractionations are consistent with theoretical predictions that the molecular ma...
-
partitioning of poly ethylene oxide poly ethylene imide and bovine serum albumin in isobutyric acid water
Macromolecules, 2008Co-Authors: Alexander I Norman, Brittney A Manvilla, Evan L Frank, Justine N Niamke, Grant D. Smith, Sandra C. GreerAbstract:We present new measurements of the partitioning of the polymers (poly(ethylene glycol) (PEG) and poly(ethylene imine) (PEI)) and the protein bovine serum albumin (BSA) between coexisting Liquid Phases of isobutyric acid + water. We show that all partition unevenly between the Liquid Phases: In all cases, there is substantially more polymer or protein in the upper, isobutyric acid-rich phase. At molecular masses above about 10 kg/mol, PEG and PEI fractionate between the Liquid Phases, with a higher average molecular mass in the lower, water-rich phase. The fractionation and partitioning are amplified both when the molecular mass of the polymer is increased, and when D2O + isobutyric acid is used instead of H2O + isobutyric acid. The dependence of the distribution coefficient on molecular mass disagrees with the predictions of Flory−Huggins mean field theory for all PEG and PEI systems studied. At low molecular weight, the PEG fractionations are consistent with theoretical predictions that the molecular ma...
-
Molecular weight distributions of polydisperse polymers in coexisting Liquid Phases
The Journal of Chemical Physics, 2002Co-Authors: R. Saurabh Shresth, R. Christopher Mcdonald, Sandra C. GreerAbstract:We present new experimental measurements of the molecular weight (MW) distributions in coexisting Liquid Phases for three polymer/solvent systems. We studied samples at the critical compositions and at four temperatures in the two-phase regions. For polystyrene in methylcyclohexane (with an upper critical solution point), we observed the expected fractionation between Phases, with a higher average MW in the lower, polymer-rich phase. For poly(ethylene oxide) in 2, 6-lutidine+water (with a lower critical solution point), the total polymer mass is nearly equal in the two Phases, but the polymers of higher average MW equilibrate into the upper, 2,6-lutidine-rich phase. For poly(ethylene oxide) in isobutyric acid+water (with an upper critical solution point), most of the total polymer mass is in the upper, isobutyric acid-rich phase, but the polymers of higher average MW equilibrate into the lower, water-rich phase; moreover, the fractionation in this case is quite dramatic, with almost a factor of 2 difference in average MW between the Phases and a significant decrease in polydispersity for the lower phase. Our results support prior experimental results on this phenomenon that find that a basic Flory–Huggins (FH) theory is inadequate. More recent theoretical considerations suggest that the difference between FH theory and experiments is due to non-mean field effects, but this theory awaits direct comparison to experiments.
Syouji Hirota - One of the best experts on this subject based on the ideXlab platform.
-
binodal curve of two Liquid Phases and solid Liquid equilibrium for water fatty acid ethanol systems and water fatty acid acetone systems
Fluid Phase Equilibria, 1997Co-Authors: Kouji Maeda, Satoshi Yamada, Syouji HirotaAbstract:Abstract To determine the Liquid-Liquid-solid three-phase equilibrium (LLSE), binodal data of the Liquid-Liquid equilibrium (LLE) and the solid-Liquid equilibrium (SLE) have been measured for the ternary water + acetone or ethanol + lauric acid, myristic acid or palmitic acid systems. The binodal region for two Liquid Phases increases successively in the following order of the third component: lauric acid myristic acid > palmitic acid. The solubility of fatty acids in aqueous solutions containing acetone is smaller than in those containing ethanol. Predictions of both the binodal curve for LLE and the SLE curve by the UNIFAC method and the NRTL equation do not represent the experimental data. However, data of the binodal curve and solubility are well correlated by the NRTL equation, and also the LLSE relationship could be represented.
Dirk De Vos - One of the best experts on this subject based on the ideXlab platform.
-
immobilization of molecular catalysts in supported ionic Liquid Phases
Dalton Transactions, 2010Co-Authors: Charlie Van Doorslaer, Joos Wahlen, Pascal Mertens, Koen Binnemans, Dirk De VosAbstract:In a supported ionic Liquid phase (SILP) catalyst system, an ionic Liquid (IL) film is immobilized on a high-surface area porous solid and a homogeneous catalyst is dissolved in this supported IL layer, thereby combining the attractive features of homogeneous catalysts with the benefits of heterogeneous catalysts. In this review reliable strategies for the immobilization of molecular catalysts in SILPs are surveyed. In the first part, general aspects concerning the application of SILP catalysts are presented, focusing on the type of catalyst, support, ionic Liquid and reaction conditions. Secondly, organic reactions in which SILP technology is applied to improve the performance of homogeneous transition-metal catalysts are presented: hydroformylation, metathesis reactions, carbonylation, hydrogenation, hydroamination, coupling reactions and asymmetric reactions.
Michelangelo Gruttadauria - One of the best experts on this subject based on the ideXlab platform.
-
Covalently Supported Ionic Liquid Phases: An Advanced Class of Recyclable Catalytic Systems
Chemcatchem, 2016Co-Authors: Francesco Giacalone, Michelangelo GruttadauriaAbstract:In this review, the most recent advances in the synthesis and catalytic applications of covalently supported ionic Liquid (IL) Phases will be discussed. This class of recyclable catalytic materials is based on the covalent attachment of several types of ammonium salts, usually imidazolium, but also thiazolium, triazolium, and pyrrolidinium salts, on the surface of different supports, for example, silica, periodic mesoporous organosilica, polystyrene, magnetic-based materials, carbon nanotubes (NTs), halloysite NTs, polyhedral oligomeric silsesquioxane (POSS), and fullerenes. Moreover, poly(ionic Liquid) materials, in which the IL-based structure also acts as a support, will be considered. The synthetic applications of these materials will be presented, with special emphasis on their roles as catalysts, without added organocatalysts or metal-based catalysts, as supports for organocatalysts, and as supports for metal-based catalysts.
Kouji Maeda - One of the best experts on this subject based on the ideXlab platform.
-
binodal curve of two Liquid Phases and solid Liquid equilibrium for water fatty acid ethanol systems and water fatty acid acetone systems
Fluid Phase Equilibria, 1997Co-Authors: Kouji Maeda, Satoshi Yamada, Syouji HirotaAbstract:Abstract To determine the Liquid-Liquid-solid three-phase equilibrium (LLSE), binodal data of the Liquid-Liquid equilibrium (LLE) and the solid-Liquid equilibrium (SLE) have been measured for the ternary water + acetone or ethanol + lauric acid, myristic acid or palmitic acid systems. The binodal region for two Liquid Phases increases successively in the following order of the third component: lauric acid myristic acid > palmitic acid. The solubility of fatty acids in aqueous solutions containing acetone is smaller than in those containing ethanol. Predictions of both the binodal curve for LLE and the SLE curve by the UNIFAC method and the NRTL equation do not represent the experimental data. However, data of the binodal curve and solubility are well correlated by the NRTL equation, and also the LLSE relationship could be represented.
