Dynamic multiphase semi-crystalline polymers based on thermally reversible pyrazole-urea bonds

• DOI: 10.1038/s41467-019-12766-6
• Publication Date: 2019-10-18T12:05:56Z
• Authors: Wen-Xing Liu; Zhusheng Yang; Zhi Qiao; Long Zhang; Ning Zhao; Sanzhong Luo; Jian Xu
• Keywords: Science; Q; 01 natural sciences; Article; 0104 chemical sciences

AbstractConstructing responsive and adaptive materials by dynamic covalent bonds is an attractive strategy in material design. Here, we present a kind of dynamic covalent polyureas which can be prepared from the highly efficient polyaddition reaction of pyrazoles and diisocyanates at ambient temperature in the absence of a catalyst. Owing to multiphase structural design, poly(pyrazole-ureas) (PPzUs) show excellent mechanical properties and unique crystallization behavior. Besides, the crosslinked PPzUs can be successfully recycled upon heating (~130 °C) and the molecular-level blending of polyurea and polyurethane is realized. Theoretical studies prove that the reversibility of pyrazole-urea bonds (PzUBs) arises from the unique aromatic nature of pyrazole and the N-assisting intramolecular hydrogen transfer process. The PzUBs could further broaden the scope of dynamic covalent bonds and are very promising in the fields of dynamic materials.