Contact drawing of core-shell polymer fibers using an aqueous two-phase system

Core-shell polymer fibers, prepared primarily through electrospinning-based approaches, have numerous applications, including spun-bonded nonwovens, optics, electronics, as well as self-healing composites, drug delivery, drug release, tissue engineering, and sensors. Our study explores the contact drawing technique and a special class of water-in-water mixtures known as aqueous two-phase systems (ATPSs) to produce core-shell fibers. This approach can be precisely tuned by immersing the end of a microneedle into the ATPS and then retracting it at a defined speed. We investigate core-shell fibers' formation over a wide range of polymer concentrations and molecular weights in the two phases. We also monitor fiber diameter by varying the retracting speed while keeping the final fiber length constant. Fibers prepared in this method are found to have fine dimensional control, continuous fabrication, low production cost and sustainability.