Thermally healable PTMG-based polyurethane elastomer with robust mechanical properties and high healing efficiency

Polymers can repair their own mechanical damage and prolong their service life by self-healing, so it has received extensive attention in recent years. But the self-healing polymers through the exchangeable dynamic covalent bonds have relatively poor mechanical performance. The polyurethanes were prepared with poly(tetramethylene ether) glycol (PTMG) as soft segments and 4,4′-diphenylmethane diisocyanate, 1,4-butanediol as hard segments, in the absence of catalyst. The change of carbamate and hydrogen bonding in polyurethane was studied by variable-temperature infrared spectroscopy. The results showed that there were exchangeable dynamic equilibria of above two. The effect of molecular weight of soft segments on the healing efficiency was also discussed. The results showed that the higher molecular weight of soft segments enhanced the microphase separation of polyurethane. It not only provided the high mechanical strength, but also facilitated the reversible exchange of carbamate and hydrogen bonding in the region of the fracture, thus promoting the self-healing effect. The study will provide a healing method for the PTMG-based polyurethane elastomer of scale production. (paper)