We show that poly­(ethylene oxide) (PEO) solutions formulated using solvent mixtures of acetonitrile (AcN) and water can be centrifugally spun into fibers. We find that spinnability and fiber morphology depend on solvent choice if polymer concentration, solution shear rheology, the number of entanglements, extensional relaxation time, and the parameters for centrifugal spinning are nearly matched. We obtain an intrinsic spinnability map for volatile entangled (VE) polymer solutions by contrasting the measured shear relaxation time with the evaporation rate determined using thermogravimetric analysis (TGA). Finally, we chart a processability map for centrifugal spinning by plotting extensional relaxation time, measured for the volatile polymer solutions using a closed-cell dripping-onto-substrate (DoS) rheometry, against the time of flight (from the nozzle to the collector) by scaling both the timescales with an evaporation time. The processability map incorporates the influence of centrifugal spinning speed, nozzle diameter, distance from the collector, ambient conditions, and solvent and polymer properties, establishing an imitable paradigm for distinguishing between spinnable and sprayable formulations.

Centrifugal force spinning (CFS), also known as centrifugal spinning, forcespinning, or rotary jet spinning, provides considerably higher production rates than electrospinning (ES), but the more widespread use of CFS as an alternative depends on the ability to produce fibers with robust thermal and mechanical properties. Here, we report the CFS of poly(ethylene oxide) (PEO) fibers made using a spinning dope formulated with acetonitrile (AcN) as the volatile solvent, and we describe the thermal and mechanical properties of the centrifugally-spun fibers. Even though the formation, diameter, and morphology of electrospun and centrifugally-spun PEO fibers are relatively well-studied, the article presents three crucial contributions: the pioneering use of PEO solutions in AcN as spinning dope, characterization of crystallinity and mechanical properties of the centrifugally-spun PEO fibers, and a comparison with the corresponding properties of electrospun fibers. We find that fiber formation occurrs for the chosen CFS conditions if polymer concentration exceeds the entanglement concentration, determined from the measured specific viscosity. Most significantly, the centrifugally spun PEO fibers display crystallinity, modulus, elongation-at-break, and fiber diameter that rival the properties of electrospun PEO fibers reported in the literature.

Designing application-ready fibers involves multifaceted challenges related to correlating the formulation properties and processing parameters to the fiber engineering trifecta of spinnability, morphology, and properties. Here, we characterize the influence of macromolecular and solvent properties on the trifecta for poly(ethylene oxide) (PEO) fibers produced using a bespoke centrifugal force spinning (CFS) setup and matched processing parameters. We illustrate the influence of changing solvent on spinnability, morphology, and properties (thermal and mechanical) by varying the acetonitrile (AcN) fraction in the spinning dope formulated with PEO dissolved in AcN/H 2 O mixtures. We contrast the numerical values of measured diameter, tensile strength, elongation-at-break, and crystallinity of centrifugally spun PEO fibers with the published data sets for electrospun fibers using the Berry number (or the overlap parameter) as the ordinate. We compile, analyze, and replot ES and CFS data sets obtained for various solvents, PEO (M w and c), and processing parameters. Even though distinct forces determine the jet trajectory and fiber formation for ES and CFS, we find that centrifugally spun PEO fibers emulate electrospun fiber properties, morphology, and spinnability. We discuss the mechanism underlying volatile-entangled spinnability, displayed here by PEO solutions in certain AcN/H 2 O mixtures, in contrast to extensibility-enriched spinnability of multicomponent formulations, enabled by the addition of an ultrahigh M w polymer fraction.

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