Hydrogen-Bond- and Shear-Field-Induced Self-Assembly for the Efficient Preparation of Polybenzoxazole Nanofibers with Excellent Mechanical Properties and Heat Resistance

Protonation and deprotonation are the main methods for the preparation of aromatic polymer nanofibers, but there are problems such as a long preparation period. Herein, we introduce amide bonds into the polybenzoxazole (PBO) chains through molecular design and propose a time-saving method for the preparation of PBO nanofibers (PBONFs) by the hydrogenbond- and shear-field-induced self-assembly. The amide bonds achieve solubilization of PBO in 1-methyl-2-pyrrolidinone (NMP) and enable the formation of strong hydrogen bonds between PBO chains. The PBO chains in the NMP solution are oriented under the shear field, then the oriented chains can be fixed by the hydrogen bonds during the solvent exchange between NMP and coagulation bath to form nanofibers with impressive properties. Notably, the preparation cycle of PBONFs is significantly shortened from 7 to 9 days to 1 h. We anticipate that this study will provide a new strategy for the preparation of aromatic polymer nanofibers with excellent mechanical properties and heat resistance.