From Spherulites to Strain-Induced Crystals: Process-Driven Crystallinity Design in Melt Electrospinning Writing of Polycaprolactone

In this study, the crystallization behavior of poly(ε-caprolactone) (PCL) under MEW processing conditions was systematically investigated to clarify its role in governing fiber morphology and functional properties. By systematically varying critical processing parameters, both the degree of crystallinity and the orientation of crystalline domains were modulated and quantitatively assessed using polarized light microscopy (PLM), scanning electron microscopy (SEM), wide-angle X-ray diffraction (WAXD), and small-angle X-ray scattering (SAXS). The findings reveal that crystallization kinetics are strongly dictated by the thermal and shear histories imposed during MEW, resulting in pronounced differences in surface topography, interfiber fusion, and layer-to-layer stacking. These microstructural transformations are further correlated with changes in alter surface roughness and wetting behavior, indicating that controlled crystallization can be exploited as a key process-driven design parameter linking fiber microstructure to interfacial and mechanical performance in MEW-fabricated constructs.