Coupling and Decoupling between Stickers and Backbones in Associating Polymers with Terminally Functionalized Side Chains

Associating polymers have recently attracted tremendous attention as self-healing polymers due to the dynamic reversibility of sticker association–dissociation processes. These sticker dynamics inevitably slow significantly as segmental dynamics decelerate below the glass transition temperature that limits the operational temperatures of associating polymers. Using broadband dielectric spectroscopy on a new set of associating polymers composed side chains of various lengths and terminal carboxylic-acid sticker functionality, we discovered an unexpected decoupling near the glass transition (Tg) between the slower backbone and fast sticker motions. These two motions have distinct activation energies for the motion of the sulfur linkage adjacent to the backbone (∼22 to 26 kJ/mol) and the carboxylic acid groups (∼5 to 8 kJ/mol). A second decoupling appears in the polymer with the longest side chain length at Tg – 20 K, reflecting the dynamics of various carboxylic acid binding configurations. Our findings open the door to design associating polymers with the capability of sticker association/dissociation at low temperatures.