Functional limitations of one-step particle integration in nanofibers: insights from needle and wire electrospinning

The fabrication of functional nanofibrous composites by one-step electrospinning relies on the assumption that incorporated particles remain accessible after fiber formation. In practice, however, particle positioning within the fibers is strongly governed by the spinning process. In this work, we compare needle-based and needleless wire electrospinning to evaluate how processing conditions influence the distribution and functional accessibility of UiO-66 and NH 2 -UiO-66 particles embedded in polyacrylonitrile (PAN) nanofibers. Although the crystalline structure of the metal organic frameworsks (MOFs) is preserved after electrospinning, X-Ray Photoelectron Spectroscopy (XPS), specific surface area analysis, and CO 2 sorption measurements show that their porosity remains largely inaccessible due to encapsulation within the polymer matrix. Needle-spun composites exhibit the strongest loss of accessible surface area and no measurable enhancement in CO 2 uptake, while wire-spun fibers show slightly higher porosity and a modest sorption increase, indicating reduced but still significant pore obstruction. These results demonstrate that electrospinning technology critically determines particle accessibility and, consequently, the functional performance of MOF/polymer composites. The findings highlight an inherent limitation of the one-step blending approach and underscore the need for surface-directed spinning strategies when accessible active sites are required for sorption or catalytic applications. • Electrospinning technology governs MOF distribution and accessibility in PAN nanofibers. • Needle spinning causes stronger MOF encapsulation than wire electrospinning. • MOF crystallinity is preserved, but porosity remains largely inaccessible. • BET and CO 2 sorption confirm technology-dependent pore blocking effects. • One-step electrospinning limits functional use of MOFs in sorption applications.