Role of weak and transient interactions in the polymer-free electrospinning of β-cyclodextrin derivatives

Polymer-free electrospinning enables the fabrication of nanofibers from low-molecular-weight compounds without polymeric additives, where intermolecular interactions or molecular aggregates substitute for polymer chain entanglements. Cyclodextrins (CDs) are among the most widely studied examples, yet the electrospinning behavior of hydrophobic CDs lacking hydroxyl groups remains poorly understood. Here, we investigated the viscosity, solubility, and spinnability of four side-chain-modified β-cyclodextrins-triacetyl (TAc), tripropionyl (TPr), tributanoyl (TBu), and triethyl (TEt)-to elucidate the role of intermolecular interactions in electrospinning. Triacetyl-β-cyclodextrin (TAc-β-CD) exhibited spinnability from supersaturated solutions, where weak interactions between carbonyl and hydrocarbon groups were suggested by viscosity, NMR, and FT-IR analyses. Comparative studies revealed that CDs with stronger intermolecular interactions and higher melting points could be electrospun at lower concentrations, while weaker interactions required higher concentrations. Notably, TEt-β-CD, which lacks carbonyl groups, was successfully electrospun across a broad concentration range (110-250 w/v%) with excellent stability, despite its weak intermolecular interactions. These results indicate that polymer-free electrospinning can proceed without the formation of stable or long-lived molecular aggregates. Rather, weak and transient intermolecular interactions at high concentrations appear sufficient to maintain the solution continuity required for fiber formation. This systematic comparison across β-cyclodextrin derivatives clarifies the physicochemical conditions under which low-molecular-weight compounds can be electrospun.