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

摘要

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 wich 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), [#eta#]_(PMMA), is less than the intrinsic viscosity of PMMA in pure solvent, [#eta#]_0, due to the repulsive intermolecular interaction between polymer chains in solution. On the contrary, in poor solvent, [#eta#]_(PMMA) is larger than [#eta#]_0, due to the attractive intermolecular interaction between polymer chains in solution. According to the equation presented in this article, the correlation between [#eta#]_(PMMA) and the concentration of PMMA in (PMMA + solvent), C_(PMMA), can be obtained by transforming the plot of the reduced viscosity(#eta#_sp/C) versus concentration of PMMA in pure solvent. It is noted that, in good solvent, [#eta#]_(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 [#eta#]_(PMMA) and C_(PMMA) became much complicated, and [#eta#]_(PMMA) increased in lower concentration of C_(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.