Supramolecular Polymer Based on Poly (Ethylene-co-Vinyl Alcohol)-g-Ureidopyrimidinone: Self-Assembly and Thermo-Reversibility

The synthesis of a poly (ethylene-co-vinyl alcohol) (EVOH)-based supramolecular polymer by graft functionalization of EVOH with ureidopyrimidinone groups (UPy) has been studied. The resulting polymer, designated as EVOH-U, has been studied from a thermo-reversibility point of view. Generally, UPy, itself, can be self-assembled through fourfold hydrogen bonding, but in dimethyl sulfoxide solvent, it favors a tautomeric form that is incapable of self-assembly. Thermal treatment was applied as a means of manipulating the tautomerism. With applying consecutive heating and annealing procedures, the disruption and reversible regeneration of UPy hydrogen bonds were investigated by differential scanning calorimetry. The results showed about 91% and 86% of the hydrogen bonds regenerated after first and second adequate thermal treatments. Dynamic mechanical-thermal analysis (DMTA) confirmed the thermo-reversibility of EVOH-U as well. Moreover, DMTA showed that, after disruption and regeneration of hydrogen bonds, the EVOH-U specimen retained its structural integrity.