Hydrogel-assisted microfluidic wet spinning of poly(lactic acid) fibers from a green and pro-crystallization spinning dope

Poly(lactic acid) (PLA) fibers have found a broad range of applications in medical textiles. While traditional spinning methods usually involve harsh conditions, such as high temperature or toxic organic solvents, the challenges in producing PLA fibers via a green route are yet to be overcome. Herein, we described a new strategy for PLA fiber production, which combines the controlled and benign spinning conditions enabled by microfluidics and a novel green spinning dope with bio-sourced CyreneTM as a non-toxic solvent for PLA. This strategy is enabled by the in-situ formation of a hydrogel shell around the focused PLA/Cyrene™ spinning dope stream. This hydrogel shell stabilizes the core stream and facilitates the solidification of the PLA fiber. Our hydrogel-assisted microfluidic wet spinning (HA-MWS) strategy represents the first-ever method that allows for the continuous room-temperature production of highly porous PLA fibers (porosity > 80 %) without the need for petroleum-based chemicals. We characterized the solution properties of the PLA/CyreneTM spinning dope and discovered that CyreneTM can induce PLA crystallization, with resultant crystals acting as cross-linking centers for the spinning dope gelation. We then explored the microfluidic wet spinning process, using the spinning dope as the core flow and the alginate aqueous solution as the shell flow to achieve controlled fiber production. The resulting PLA fibers underwent comprehensive morphological, structural, and mechanical characterization. Our process enables the green production of PLA fibers under mild conditions. More importantly, a bio-based green and pro-crystallization solvent was for the first time used to develop PLA spinning dope, which gives rise to a range of promising fiber properties (e.g. high porosity), which can broaden potential biomedical applications of PLA fibers.