Controlling Polymer Microfiber Structure by Micro Solution Blow Spinning
Hofmann, Eddie ; Dulle, Martin ; Liao, Xiaojian ; Greiner, Andreas ; Förster, Stephan
Macromolecular Chemistry and Physics. Bd. 221 (2020) https://doi.org/10.1002/macp.201900453
Recent progress in microfluidic technology allows fabricating microfluidic devices to produce liquid microjets with unprecedented control of the jet diameter and velocity. Here it is demonstrated that microfluidic devices based on the gas dynamic virtual nozzle principle can be excellently used for micro solution blow spinning to continuously fabricate microfibers with excellent control of the fiber diameter and the internal crystalline alignment that determines the mechanical properties. Fiber spinning experiments with small‐ and wide‐angle X‐ray scattering are combined to directly relate the macroscopic spinning conditions to the bulk and molecular structure of the resulting fibers. The elongational rate is shown as the relevant parameter that transduces the nozzle flow conditions to the local macromolecular structure and orientation, and thus the mechanical properties of the resulting fiber. It is observed that the spinning process results in very uniform microfibers with a well‐defined shish–kebab crystal structure, which evolves into an extended chain crystal structure upon plastic deformation. Thus, the presented microfluidic spinning methodology has great implications for a precisely controlled production of microfibers using miniaturized spinning devices.