Determination of Entangled Supramolecular Polymer Networks Dynamics by High-Order Associations of Strong Hydrogen Bonding Groups
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Dynamics of entangled polymer chains in the melt state are deliberately excluded in most of the studies on supramolecular polymer networks by utilizing non-entangled precursor chains. Relaxation of the system mainly depends on the dissociation of the associative groups in latter case and non-entangled chains deliver nothing to resist afterwards. Conversely, in an entangled system relaxation of polymer chains and dissociation of associative groups can occurred parallel. Supramolecular networks based on an entangled precursor polymer with different levels of strong associating ureidopyrimidinone, UPy, groups are synthesized to screen the corresponding effects on the dynamics of the system. Binary-associated UPy groups phase separate into collective assemblies by stacking and form high-order, needle-like domains at higher UPy contents. Relaxation of polymer chains is significantly hindered due to the trapping of polymer segments between UPy stacks. Above a certain threshold of UPy content (~4 mol%), the plateau level as well as final relaxation time of networks show a significant jump, which is attributed to the onset of high-order association of UPy groups.
KeywordsSupramolecular networks High order associations Chain dynamics Chain entanglements Ureidopyrimidinone groups