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

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), ηPMMA, is less than the intrinsic viscosity of PMMA in pure solvent, η0, due to the repulsive intermolecular interaction between polymer chains in solution. On the contrary, in poor solvent, ηPMMA is larger than η0, due to the attractive intermolecular interaction between polymer chains in solution. According to the equation presented in this article, the correlation between ηPMMA and the concentration of PMMA in (PMMA + solvent), CPMMA, can be obtained by transforming the plot of the reduced viscosity(ηsp/C) versus concentration of PMMA in pure solvent. It is noted that, in good solvent, ηPMMA decreased with the increase of CPMMA in solution, indicating that the polymer chains shrank in size in concentrated solutions. However, in poor solvent, the correlation between ηPMMA and CPMMA became much complicated, and ηPMMA increased in lower concentration of CPMMA and decreased in higher concentration of CPMMA, which can be attributed to both the attractive intermolecular interaction and the concentration-dependent excluded volume effect in solution.