From Nanofibrous Hollow Microspheres to Nanofibrous Hollow Discs and Nanofibrous Shells

摘要

Nano- and micro-sized structures are of central importance to advanced materials and nanotechnologies, which have tremendously impacted both biomedical and physical sciences. Herein, we report novel emulsification and thermally-induced phase separation (TIPS) techniques to fabricate linear polymers into nanofibrous hollow objects for the first time. Through manipulating the emulsification conditions, we can control the evolution of the emulsion structure and fabricate nanofibrous hollow microspheres with controllable opening size and nanofibrous shells. Through adjusting the rheological properties of the emulsions, we also create nanofibrous hollow discs. We then propose new mechanistic hypotheses of the nanofibrous hollow object formation: the nano- and micro-scaled structure are independently determined by TIPS and emulsification process, respectively. Guided by this theory, we identify the nanofiber formation conditions for two further additional polymers (polyacrylonitrile and Nylon) under TIPS, and create solidanofibrous non-hollow/hollow microspheres from these two additional polymers under TIPS and emulsification for the first time. Therefore, the developed strategy is applicable to various polymer systems, and can broadly impact nano- and micro-fabrication technologies.