The molecular dynamics computer simulation technique has been applied to study the hydration of b... more The molecular dynamics computer simulation technique has been applied to study the hydration of bis(methylsulphonyl)methane (1) in water. This 1,3-disulphone has water-structure breaking properties as is deduced from both simulated time-averaged and time-dependent properties. The time-averaged properties of water molecules in the various atomic hydration shells can be directly related to the solute atom under consideration. Time-dependent properties show a mutual influencing of the hydration shells of neighbouring atoms. Moderate sulphonyl oxygen-water hydrogen bonding competes with water-water hydrogen bonding in the same hydration shell, while methylene hydrogen-water hydrogen bonding is stronger than water-water hydrogen bonding. These results are in accord with previous interpretations of 1H-N.M.R. chemical shift data for the central methylene moiety of (1) in mixtures of water with 1,4-dioxane, 1,3-dioxane, and 1,2-dimethoxyethane.
Page 1. Recueil des Travaux Chimiques des Pays-Bus, 10413, march 1985 79 Recl. Trav. Chim. Pays-B... more Page 1. Recueil des Travaux Chimiques des Pays-Bus, 10413, march 1985 79 Recl. Trav. Chim. Pays-Bas 104, 79-89 (1985) 0034-186X/85/03079-11$3.25 Molecular dynamics computer simulation as a tool for the analysis ...
The hydration of two simple organic solutes has been studied using the molecular dynamics (MD) co... more The hydration of two simple organic solutes has been studied using the molecular dynamics (MD) computer simulation method. Results of the simulations of a single 1,4-dioxane or 1,3-dioxane molecule dissolved in 122 water molecules are compared with those of a MD simulation of an empty cavity of corresponding size in 216 water molecules. This yields the opportunity to trace the specific effects of the polar and dispersion solute-solvent interactions on the properties of the water molecules in the hydration shell of the solute. The hydration shell properties of 1,4-dioxane (mu) = 0·14 D) are very similar to those of the corresponding cavity, whereas those of 1,3-dioxane (mu) = 1·91 D) show significant deviations. Earlier conclusions that water structure-making and water structure-breaking properties of 1,4-dioxane are about equally balanced, while 1,3-dioxane is definitely structure-breaking, are confirmed. Moreover, it is shown that a slower self-diffusion and reorientation of water molecules upon addition of a cosolvent does not necessarily point at structure-making properties, additional to those that are already induced by the cavity formation. The introduction of an empty cavity also slows down self-diffusion and molecular reorientation in the hydration shell.
ABSTRACT A combination of DSC, SAXS, WAXD, 1H time-domain, and frequency domain NMR measurements ... more ABSTRACT A combination of DSC, SAXS, WAXD, 1H time-domain, and frequency domain NMR measurements was used for determining the amount of rigid/crystallinity, semirigid, and soft fractions of iPP. Changes in the rigid, semirigid, and soft fractions of isotactic polypropylene (iPP) were investigated as a function of temperature, annealing time, and annealing temperature. The most probable iPP morphology was established by TEM and by comparing 1H spin-diffusion data with data from multidimensional solutions of the spin-diffusion equations. Proton NMR spin-diffusion method, which employs double-quantum (DQ) and Goldman−Shen dipolar filters, was used in order to provide the domain thickness in iPP. The temperature dependence of spin diffusivities was taken into account, and a semiquantitative theory is presented for this dependence in the case of amorphous domains. A combination of 1H spin-diffusion NMR and SAXS was used to estimate the lamellar thicknesses for nonannealed and annealed iPP samples. Annealing at temperatures above 110 °C causes increases in the lamellar thickness and the crystallinity and a decrease in the chain mobility of rigid and semirigid fractions. The above quantities and the chain dynamics are reported for three annealing temperatures, 134, 143, and 153 °C, and an annealing time in the range of 15 min to 30 h. It is shown that the crystalline domains thickening during annealing of iPP can be described by a model based on irreversible thermodynamics. A phenomenological correlation is established between 1H transverse magnetization relaxation rate of the rigid fraction of iPP and the annealing temperatures.
ABSTRACT Fractionation techniques such as temperature rising elution fractionation or crystalliza... more ABSTRACT Fractionation techniques such as temperature rising elution fractionation or crystallization analysis fractionation fail to fractionate the ethylene–propylene (EP) copolymers, which are a component of high-impact polypropylene (hiPP), according to their chemical composition. High-temperature high-performance liquid chromatography separates blends of EP-copolymers and polypropylene. The elution volume of the EP-copolymers depends linearly on the average content of ethylene. The separation according to the chemical composition was hyphenated with size exclusion chromatography. In this way, the relationship between the distribution with regard to chemical composition and molar mass, that is, the full chemical heterogeneity of hiPP, was revealed for the first time.
The molecular dynamics computer simulation technique has been applied to study the hydration of b... more The molecular dynamics computer simulation technique has been applied to study the hydration of bis(methylsulphonyl)methane (1) in water. This 1,3-disulphone has water-structure breaking properties as is deduced from both simulated time-averaged and time-dependent properties. The time-averaged properties of water molecules in the various atomic hydration shells can be directly related to the solute atom under consideration. Time-dependent properties show a mutual influencing of the hydration shells of neighbouring atoms. Moderate sulphonyl oxygen-water hydrogen bonding competes with water-water hydrogen bonding in the same hydration shell, while methylene hydrogen-water hydrogen bonding is stronger than water-water hydrogen bonding. These results are in accord with previous interpretations of 1H-N.M.R. chemical shift data for the central methylene moiety of (1) in mixtures of water with 1,4-dioxane, 1,3-dioxane, and 1,2-dimethoxyethane.
Page 1. Recueil des Travaux Chimiques des Pays-Bus, 10413, march 1985 79 Recl. Trav. Chim. Pays-B... more Page 1. Recueil des Travaux Chimiques des Pays-Bus, 10413, march 1985 79 Recl. Trav. Chim. Pays-Bas 104, 79-89 (1985) 0034-186X/85/03079-11$3.25 Molecular dynamics computer simulation as a tool for the analysis ...
The hydration of two simple organic solutes has been studied using the molecular dynamics (MD) co... more The hydration of two simple organic solutes has been studied using the molecular dynamics (MD) computer simulation method. Results of the simulations of a single 1,4-dioxane or 1,3-dioxane molecule dissolved in 122 water molecules are compared with those of a MD simulation of an empty cavity of corresponding size in 216 water molecules. This yields the opportunity to trace the specific effects of the polar and dispersion solute-solvent interactions on the properties of the water molecules in the hydration shell of the solute. The hydration shell properties of 1,4-dioxane (mu) = 0·14 D) are very similar to those of the corresponding cavity, whereas those of 1,3-dioxane (mu) = 1·91 D) show significant deviations. Earlier conclusions that water structure-making and water structure-breaking properties of 1,4-dioxane are about equally balanced, while 1,3-dioxane is definitely structure-breaking, are confirmed. Moreover, it is shown that a slower self-diffusion and reorientation of water molecules upon addition of a cosolvent does not necessarily point at structure-making properties, additional to those that are already induced by the cavity formation. The introduction of an empty cavity also slows down self-diffusion and molecular reorientation in the hydration shell.
ABSTRACT A combination of DSC, SAXS, WAXD, 1H time-domain, and frequency domain NMR measurements ... more ABSTRACT A combination of DSC, SAXS, WAXD, 1H time-domain, and frequency domain NMR measurements was used for determining the amount of rigid/crystallinity, semirigid, and soft fractions of iPP. Changes in the rigid, semirigid, and soft fractions of isotactic polypropylene (iPP) were investigated as a function of temperature, annealing time, and annealing temperature. The most probable iPP morphology was established by TEM and by comparing 1H spin-diffusion data with data from multidimensional solutions of the spin-diffusion equations. Proton NMR spin-diffusion method, which employs double-quantum (DQ) and Goldman−Shen dipolar filters, was used in order to provide the domain thickness in iPP. The temperature dependence of spin diffusivities was taken into account, and a semiquantitative theory is presented for this dependence in the case of amorphous domains. A combination of 1H spin-diffusion NMR and SAXS was used to estimate the lamellar thicknesses for nonannealed and annealed iPP samples. Annealing at temperatures above 110 °C causes increases in the lamellar thickness and the crystallinity and a decrease in the chain mobility of rigid and semirigid fractions. The above quantities and the chain dynamics are reported for three annealing temperatures, 134, 143, and 153 °C, and an annealing time in the range of 15 min to 30 h. It is shown that the crystalline domains thickening during annealing of iPP can be described by a model based on irreversible thermodynamics. A phenomenological correlation is established between 1H transverse magnetization relaxation rate of the rigid fraction of iPP and the annealing temperatures.
ABSTRACT Fractionation techniques such as temperature rising elution fractionation or crystalliza... more ABSTRACT Fractionation techniques such as temperature rising elution fractionation or crystallization analysis fractionation fail to fractionate the ethylene–propylene (EP) copolymers, which are a component of high-impact polypropylene (hiPP), according to their chemical composition. High-temperature high-performance liquid chromatography separates blends of EP-copolymers and polypropylene. The elution volume of the EP-copolymers depends linearly on the average content of ethylene. The separation according to the chemical composition was hyphenated with size exclusion chromatography. In this way, the relationship between the distribution with regard to chemical composition and molar mass, that is, the full chemical heterogeneity of hiPP, was revealed for the first time.
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