Influence of solvent solubility parameter on the power law exponents and critical concentrations of one soluble polyimide in solution

Abstract

Solvent species influence the interactions of dissolved polymers in solution and consequently induce changes in solution properties. A soluble polyimide was synthesized through polycondensation, and four solvents, namely, N,N-dimethylacetamide (DMAc), N-methyl pyrrolidone (NMP), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO), were selected to investigate systematically the influence of solubility parameter on solution power law behaviors. The power law relationship between specific viscosity and concentration was established using rheology and applying concepts from the Zimm, Rouse-Zimm, and Doi-Edwards models. All power law exponents were higher than theoretical predictions, and in the three concentration regions, i.e. dilute, semidilute unentangled, and semidilute entangled, the exponents increase, decrease, and increase, respectively, with respect to solubility parameter. Arguments derived from the listed models are proposed to explain these trends. The influences of solubility parameter on the overlap and entanglement concentrations are also discussed.

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