Flory-Huggins Interaction Parameter

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Synonyms

Polymer-solvent interaction

Definition

The Flory-Huggins interaction parameter χ gives a measure of the interaction of the polymer chains with the solvent molecules as well as the polymer-polymer interaction. To understand the meaning of χ, one must consider the free energy of mixing of pure polymer with pure solvent as considered by Flory and Huggins theory. This theory considers the free energy of mixing of pure polymer with pure solvent, ΔGmix, in terms of two contributions, namely, the enthalpy of mixing, ΔHmix, and the entropy of mixing, ΔSmix. The entropy of mixing is determined by the volume fractions of solvent and polymer, whereas the enthalpy of mixing is determined by the dimensionless interaction parameter χ. χkT (where k is the Boltzmann constant and T is the absolute temperature) expresses the difference in energy of a solvent molecule in pure solvent compared to its immersion in pure polymer. χ is usually referred to as the Flory-Huggins interacti ...