Thermodynamic quality of solvent

Kulicke, W. M., and Haas, R. (1984). Flow behavior of dilute polyacrylamide solutions through porous media. 1. Influence of chain length, concentration, and thermodynamic quality of solvent, lnd. Eng. Chem. Fund. 23 308-315. 

Discontinuous and continuous collapse of PCEPAC and poly(carboxyethyl 3-cyclohexylaminocrotonate) (PCECHAC) hydrogels was observed [221] in water/acetone and water/ethanol mixtures (Fig. 4). These results confirm the universal behavior of hydrogels with respect to the thermodynamic quality of solvents. 

Compared with their size in the amorphous state, macromolecules are expanded in good solvents whereas they tend to shrink in poor solvents. In other words, size of macromolecules of given polymer with given molar mass in solution depends on thermodynamic quality of solvent. It is characterized by the expansion... 

Stated that depending on the thermodynamic quality of solvent, the same macromolecule can assnme various conformations and consequently also different sizes in solution Similar thoughts are to be applied also considering role of solvents in liquid chromatography systems, in which macromolecules necessarily interact with eluent molecules. However, the third component has to be taken into account in polymer HPLC, namely the column packing and its interactions not only with the macromolecules of sample but also with the eluent moleeules. 

The second virial coefficient is an additional result that provides information about the polymer-solvent interactions and thus about thermodynamic quality of solvent that increases with increasing value of Ax. The Ax decreases with increasing molar mass, which explains decreasing solubility of polymers with increasing molar mass. 

The thermodynamic quality of solvents for a polymer is represented by values of the Mark-Houwink constants. Constants a and iC, included in Table 4, were deter-... 

Polymer and Highest Molar Mass Mobile Phase Thermodynamic Quality of Solvents Column Packing Ref. 

In tmeharged gels, the equilibrium swelling depends mainly on the thermodynamic quality of solvent with respect to the polymer and on the cross-linldng density, that is, on the length of subchains, which limits their maximum extension. " ... 

The adsorption of polymers from solutions strongly depends on the thermodynamic quality of solvent and the interaction energy between polymer and surface. All theories of adsorption include the thermodynamic parameter of interaction of the Flory-Huggins theory %i2. The thermodynamic interaction between polymer and solvent determines the conformation of macromolecules in solutions and thus the conditions of its interaction with the surface. The interaction between polymer and surface is characterized by the parameter of thermodynamic interaction, which was introduced by Silberberg, using the model of quasi-crystalline lattice of the surface layer, describing the properties of polymer solutions. This parameter may be determined as follows ... 

Figmes 6.6.1 and 6.6.2 show the results of numerical solution of the boundary problem for a variety of solutions of x One can see how the nature of the diffusion process and the shape of swelling kinetic curves changes depending on the deterioration of the thermodynamic quality of solvent. Particularly, it can be seen that as the parameter Floiy-Huggins increases the interval of the boundary concentration decreases, and swelling kinetic curves transform to kinetic curve of the normal sorption. 

The effect of the thermodynamic quality of solvent on the swelling kinetics of elastomeric polymer networks was theoretically and experimentally studied. Swelling is considered as a set of interrelated processes of diffusion and strain of a material. It is shown that the quality of a solvenf estimated by the Floiy-Huggins parameter value, significantly affects the nature of kinetic curves of polymer network swelling. 

Phase transitions in polymer-polymer and gel-linear polymer systems consisting of complexes of acrylic acid/butyl vinyl ether copolymers with linear and crosslinked poly-N-vinyIpyrrolidone, 1,2,5-trimethyl-4-vinylethynylpiperidinol-4/N-vinylpyrrolidone copolymer with linear and crosslinked polyacrylic acid, polyacrylic acid with crosslinked poly-N-vinylcaprolactam taking place as a function of internal (composition of copolymers) and external (thermodynamic quality of solvents, degree of ionization, temperature) factors have been investigated. In most cases the analogy in behavior of interpolymer complexes in a solution and gel-polymer complexes is observed. 

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