Viscometric investigations on the intrinsic viscosity of poly(methyl methacrylate) (PMMA) affected by polymer–polymer interactions in binary system

Abstract

The viscosity behavior of poly(methyl methacrylate) (PMMA) (referred to as guest polymer) in pure solvent and in a solvent containing a constant concentration of PMMA (referred to as host polymer) was thoroughly investigated. It has been found that the solvent in which the PMMA was dissolved played a key role in the determination of polymer–polymer interactions in solution, and thus the viscosity behavior of PMMA in a solvent. In good solvent, the intrinsic viscosity of PMMA in (PMMA + solvent), η PMMA , is less than the intrinsic viscosity of PMMA in pure solvent, η 0 , due to the repulsive intermolecular interaction between polymer chains in solution. On the contrary, in poor solvent, η PMMA is larger than η 0 , due to the attractive intermolecular interaction between polymer chains in solution. According to the equation presented in this article, the correlation between η PMMA and the concentration of PMMA in (PMMA + solvent), C PMMA, can be obtained by transforming the plot of the reduced viscosity( η sp/ C) versus concentration of PMMA in pure solvent. It is noted that, in good solvent, η PMMA decreased with the increase of C PMMA in solution, indicating that the polymer chains shrank in size in concentrated solutions. However, in poor solvent, the correlation between η PMMA and C PMMA became much complicated, and η PMMA increased in lower concentration of C PMMA and decreased in higher concentration of C PMMA, which can be attributed to both the attractive intermolecular interaction and the concentration-dependent excluded volume effect in solution.