Effects of Surfactants on the Linear Rheology of Telechelic Associating Polymers

Abstract

The influence of low-molecular-weight surfactants on the linear rheology of telechelic associating polymers is studied on the basis of the transient network theory. It is shown that dynamic shear moduli are well described in terms of a Maxwell model characterized by a plateau modulus G _∞ and a single relaxation time τ. As reported experimentally, a peak appears in G _∞ and τ (and therefore in the zero-shear viscosity) with an increase in the surfactant concentration under the conditions that the junction multiplicity has upper and lower bounds and that the formation of the pairwise junctions is allowed. As the surfactant concentration increases, a contraction occurs followed by the extension of the concatenated chain comprising several polymers connected in series. The peak of the relaxation time is attributed to this contraction and extension. On the other hand, the peak of the plateau modulus is attributed to the upper and lower bounds on the multiplicity, as suggested by Tanaka [Macromolecules (1998) 31: 384].