Tuning the Viscoelasticity of Hydrogen-Bonded Polymeric Materials through Solvent Composition

Abstract

The interactions between polymer molecules in solution are strongly affected by the way that the constituent polymers interact with the solvent. In this work, we use a mixed solvent system (dimethyl sulfoxide and ethylene glycol) to tailor the strength of the hydrogen-bonding interactions between partially quaternized poly(4-vinylpyridine) [QVP] and poly(methacrylic acid) [PMAA]. The charge introduced by the quaternization reaction enables homogeneous solutions to be formed over a large concentration range, even in the presence of attractive hydrogen-bonding interactions between the proton-donating PMAA and the proton-accepting QVP. The viscoelastic properties of equimolar QVP/PMAA solutions are superposed onto master curves that are well-described by a fractional Maxwell liquid model. This model provides a means for quantifying the dependence of the relaxation times on the solvent composition. These relaxation times increase by a factor of 1000 as the hydrogen-bonding interactions are strengthened by a decrease in the DMSO content of the solvent, within a composition regime where the solutions remain homogeneous. A much stronger effect is obtained when the ethylene glycol is replaced by water.