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 conce ntration 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, th e intrinsic viscosity of PMMA in (PMMA + solvent), [eta](PMMA), is less tha n the intrinsic viscosity of PMMA in pure solvent, [eta](o), due to the rep ulsive intermolecular interaction between polymer chains in solution. On th e contrary, in poor solvent, [eta](PMMA) is larger than [eta](o), due to th e attractive intermolecular interaction between polymer chains in solution. According to the equation presented in this article, the correlation betwe en [eta](PMMA) and the concentration of PMMA in (PMMA + solvent), C-PMMA, c an 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 so lvent, [eta](PMMA) decreased with the increase of CPMMA in solution, indica ting that the polymer chains shrank in size in concentrated solutions. Howe ver, in poor solvent, the correlation between [eta](PMMA) and C-PMMA became much complicated, and [eta](PMMA) increased in lower concentration of C-PM MA and decreased in higher concentration of C-PMMA, which can be attributed to both the attractive intermolecular interaction and the concentration-de pendent excluded volume effect in solution. (C) 2000 Elsevier Science Ltd. All rights reserved.