In‐situ Robust Polymeric Networks Prepared via Facile Uncatalyzed Huisgen Cycloaddition of Alkyne‐terminated Polyurethane with Terminal Azides

We carried out catalyst – and solvent‐free Huisgen azide‐alkyne cycloadditon (AAC) to develop the polyurethane‐based networks crosslinked through triazole moieties at chain‐ends. An asymmetrical divalent compound carrying the hydroxyl and electron‐deficient alkyne as terminal groups was newly synthesized to prepare the alkyne‐terminated polymer containing urethane moieties within polymer backbone. Additionally, three kinds of terminal‐azide crosslinkers were introduced to react with alkyne‐terminated polyurethanes without any promoters. Kinetics of the uncatalyzed AAC were monitored by using real‐time FT‐IR technique at 50 °C temperature. The rate of AAC using aromatic azide dipole was faster than other dipoles. Compared to the non‐polyurethane‐based networks crosslinked via either urethane or triazole moieties at chain‐ends, triazole chain‐ends crosslinked polyurethane networks conveyed the excellent mechanical properties. However, thermal properties at low temperature were not as good as those of non‐polyurethane networks. Especially, Tg of polyurethane networks formed by an oligomeric azide crosslinker was much higher than others.