Interplay of entanglement and association effects on the dynamics of semidilute solutions of multisticker polymer chains

Abstract

We analyze the effects of polymer concentration, Cp, and physical crosslinking ratio, rc, on the linear viscoelasticity of lightly entangled, linear, associating polymers with multiple crosslinkable groups along the chain backbone. To accomplish this goal, we utilize three novel tools: a robust tunable chemistry based on electrophilic methacryl-succinimidyl modified poly(N-isopropylacrylamide); a modified state-of-the-art entanglement theory, called the discrete slip-link molecular model; and a novel experimental technique, surface fluctuation specular reflection. This experimental technique allows the extraction of the complex viscoelastic modulus covering up to six decades of frequency, from the sample's surface fluctuations at constant temperature. We demonstrate that our theoretical model with a consistent set of parameters can qualitatively reproduce the observed features of the complex viscoelastic modulus over the entire probed frequency range. Furthermore, the effects of Cp and rc on the viscoelastic properties agree with scaling laws predicted by the “sticky reptation model” and other published experimental data. Finally, we discuss nonadditivity of the effects of entanglements and transient associations.