Phase Stability of Hydrogen-Bonded Polymer Mixtures: Application of the Quasichemical Theory

1995 ◽  
Vol 60 (11) ◽  
pp. 1830-1854
Author(s):  
Julius Pouchlý ◽  
Antonín Živný ◽  
Antonín Sikora
Keyword(s):  
Relative Size ◽  
Molecular Surface ◽  
Polymer Mixtures ◽  
Main Attention ◽  
Model Calculations ◽  
Small Deviations ◽  
Polar Groups ◽  
Energy Of Mixing ◽  
Gibbs Energy Of Mixing ◽  
Random Mixing

Expressions for the second derivative of Gibbs energy of mixing with respect to composition and/or the corresponding Flory-Huggins interaction parameter are derived using the Barker-Guggenheim quasichemical theory. The calculation is performed first for a system of compounds with a homogeneous molecular surface, then for a binary mixture of molecules the surface of which consists of various kinds of contact sites. The result is expressed in terms of "indexes of nonrandomness", the factors which characterize deviations of individual types of contact pairs from random mixing at a given composition. Main attention is paid to a mixture of substances, each of which contains a different type of polar groups and a nonpolar residue which is similar for both components. Translucent relations are obtained in two limit cases, namely for small deviations from random mixing and for small attraction between polar and nonpolar groups. The effect of the relative size of the polar groups and of the affinity to formation of various heterocontacts is illustrated using the limit relations derived, as well as by means of model calculations.

Phase Stability of Hydrogen-Bonded Polymer Mixtures. II. Mixtures of Intercomplexing Polymers

1999 ◽  
Vol 64 (1) ◽  
pp. 13-30
Author(s):  
Julius Pouchlý ◽  
Antonín Živný ◽  
Antonín Sikora
Keyword(s):  
Phase Separation ◽  
Gibbs Energy ◽  
Second Derivative ◽  
Polar Group ◽  
Polymer Mixtures ◽  
Phase Instability ◽  
Polar Groups ◽  
Energy Of Mixing ◽  
Gibbs Energy Of Mixing ◽  
The Difference

Equations for the second derivative of the Gibbs energy of mixing with respect to composition were derived on the basis of the Barker-Guggenheim theory of quasichemical equilibrium for mixtures of two polymers containing polar groups and a nonpolar rest. Using equations derived, conditions for the phase separation in mixtures of two strongly intercomplexing polymer components were evaluated. The phase instability appears when the components differ in their polar group contents (strictly speaking, in their surface fractions in respective macromolecules), or due to an unfavorable interaction between nonpolar groups of the components. The effect is conditioned by small affinity of polar to nonpolar groups and may be influenced by the difference in this affinity between both components; nevertheless, the latter factors are not sufficient for a phase instability to occur.

scholarly journals Modelling thermodynamic properties of binary Cu–Eu and ternary Al–Cu–Eu melts

2020 ◽  
Vol 8 (2) ◽  
pp. 73-82
Author(s):  
Natalia Kotova ◽  
Natalia Golovata ◽  
Natalia Usenko
Keyword(s):  
Thermodynamic Properties ◽  
Gibbs Energy ◽  
Excess Gibbs Energy ◽  
Model Calculations ◽  
Gibbs Energies ◽  
Excess Gibbs Energies ◽  
Energy Of Mixing ◽  
Gibbs Energy Of Mixing ◽  
Associated Solution Model ◽  
Associated Solution

Model calculations of the whole set of thermodynamic properties of liquid alloys for the binary Cu–Eu and ternary Al–Cu–Eu systems have been performed. Authors used the ideal associated solution model (IAS model) for calculation of the entropies and excess Gibbs energies of mixing for these systems. The binaries were given as the Redlich-Kister polynomials. The thermodynamic properties for the ternary system are described using the Redlich-Kister-Muggianu formalism. A comparison of the surfaces of excess Gibbs energy and entropy of mixing for liquid Al–Cu–Eu alloys at 1350 K demonstrates that the ordering related to the formation of rather strong associates in the Al–Eu system significantly affects the concentration dependence of the excess Gibbs energy of mixing in the liquid phase at this temperature.

Activities of Components in the Ca2MgSi2O7-CaSiO3Molten System

1996 ◽  
Vol 61 (6) ◽  
pp. 837-843
Author(s):  
Ladislav Kosa ◽  
Ivan Nerád ◽  
Katarína Adamkovičová ◽  
Jozef Strečko ◽  
Ivo Proks
Keyword(s):  
Gibbs Energy ◽  
Molar Mass ◽  
Excess Entropy ◽  
Enthalpy Of Mixing ◽  
Real Particle ◽  
Entropy Of Mixing ◽  
Energy Of Mixing ◽  
Gibbs Energy Of Mixing

Activities of the components, the Gibbs energy of mixing, and the excess entropy of mixing have been calculated for the Ca2MgSi2O7-CaSiO3 system. The mole fractions of the components were calculated assuming that in the point of the formal component Ca2MgSi2O7, the molar mass of the quasi-real particle in the melt corresponds to its formula molar mass, whereas in the point of the formal component CaSiO3 the molar mass of the quasi-real particle in the melt is 8.5 times higher than as corresponds to its formula. The fact that the enthalpy of mixing is zero whereas the excess entropy of mixing is non-zero suggests that Ca2MgSi2O7-CaSiO3 melts behave as athermal solutions.

scholarly journals In Silico–Based Structural Analysis of Arylthiophene Derivatives for FTase Inhibitory Activity, hERG, and Other Toxic Effects

2011 ◽  
Vol 16 (9) ◽  
pp. 1037-1046 ◽  
Author(s):  
N. S. Hari Narayana Moorthy ◽  
Sergio F. Sousa ◽  
Maria J. Ramos ◽  
Pedro A. Fernandes
Keyword(s):  
Inhibitory Activity ◽  
In Silico ◽  
Linear Regression Analysis ◽  
Multiple Linear Regression Analysis ◽  
Quantitative Structure Activity Relationship ◽  
Structural Features ◽  
Molecular Surface ◽  
Polar Groups ◽  
The Common

In the present investigation, the authors have performed an in silico–based analysis on a series of arylthiophene derivatives for the determination of their structural features responsible for farnesyltransferase (FTase) inhibitory activity, hERG blocking activity, and toxicity by quantitative structure–activity relationship and pharmacophore analysis techniques. The statistically significant models derived through multiple linear regression analysis were validated by different validation methods. The applicability of the descriptors contributed in the selected models show that the polar and polarizable properties on the van der Waals (vdW) surface area of the molecules are important for the FTase inhibitory and hERG blocking activities, while being detrimental for the toxicity of the molecules. It is interesting to note that the topological properties, molecular flexibility, and connectivity of the molecules are positively correlated to all the activities (FTase inhibition, hERG blocking, and toxicity). This implies that the flexibility of the molecules is the common feature for interaction in all targets, whereas the presence of polar groups on the molecular surface (vdW) is a determinant for the favorable (FTase inhibition) or unwanted effect (hERG blocking and toxicity) of the molecules. The pharmacophore analysis of the molecules demonstrated that the aromatic/hydrophobicity and polarizability features are important pharmacophore contours favorable for these activities.

Phase Stability of Hydrogen-Bonded Polymer Mixtures. III. Spinodal Diagrams

1999 ◽  
Vol 64 (1) ◽  
pp. 31-43 ◽  
Author(s):  
Julius Pouchlý ◽  
Antonín Živný ◽  
Antonín Sikora
Keyword(s):  
Relative Content ◽  
Strong Interactions ◽  
Polar Group ◽  
Polymer Mixtures ◽  
Phase Instability ◽  
Temperature Range ◽  
Polar Groups ◽  
Boltzmann Function ◽  
Chain Lengths ◽  
Two Temperature

Relations derived on the basis of the Barker-Guggenheim quasichemical theory were used for construction of spinodal diagrams (temperature versus composition) of a mixture of two polymers in which hydrogen bonds and other strong interactions exist. A function dependence of parameters of quasichemical equilibrium, η, was proposed, which has the form of the Boltzmann function at lower temperatures, but at higher temperatures corresponds to random mixing. The spinodal diagrams were constructed for several sets of dependences of η on temperature in a wide temperature range for different chain lengths, r, or for different values of the content of polar groups in one of the polymers. According to circumstances, the phase diagram shows one or two temperature regions of phase instability or the phase instability occurs in a certain range of composition at any temperature. Though the chain length was chosen equal for both polymers, the phase diagrams are asymmetric in the sense that the critical points are shifted towards that border of the diagram which corresponds to the component with a larger relative content of the polar group. The temperature range of phase instability is strongly influenced by small changes in the relative surface area of polar groups in the molecules.

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