Linear viscoelasticity of double associative polymers with varied density of the secondary interaction

Abstract

This study examines the linear viscoelasticity of double-associative ionomers based on poly(hexyl methacrylate). The ionomer samples are unentangled and contain a fixed number of ionic stickers per chain, fion≅4, but a varied number of hydrogen-bonding stickers per chain, fH = 5.5–27. Increasing fH has distinct effects on the glassy and rubbery dynamics. On the one hand, the glassy relaxation mode distribution broadens, and the glassy-to-rubbery transition region delays significantly with increasing fH. On the other hand, the delay of the ionic dissociation and, accordingly, the terminal relaxation (activated by continuous ionic dissociations) are much weaker. This contrast suggests that the ionic dissociation is not only activated by the segmental motion of the main backbone but is also partly activated by the motion of the side chains that is less dependent on fH.