Influence of the rheological behavior of polycaprolactone-borosilicate hybrid compositions on the electrospinning fibers' performance

• Sol-gel chemistry determines hybrid solution rheology and processing stability • P1 protocol yields a 6-hour electrospinning window, producing larger, porous fibers • P2 protocol limits the processing window to 2 hours, forming smaller, denser fibers • Viscosity and crosslinking degree control hybrid-solution behavior and nanofiber morphology The successful electrospinning of hybrid sol-gel organic-inorganic fibers is challenging, as it relies on the viscosity and temporal stability of the precursor solution. In sol-gel, ongoing hydrolysis-condensation reactions continuously modify rheology, thereby influencing fiber diameter and morphology. To address this, two distinct sol-gel protocols (P1 and P2) were developed by varying water, acid, solvent, and concentration levels to tune crosslinking kinetics. The protocols exhibited different stability profiles and processing windows, resulting in class I hybrids with tailored morphologies. P1 provided a longer 6-hour processing window, yielding porous membranes with larger fibers (∼500 nm), while P2 produced denser membranes with smaller fibers (∼100 nm) within a 2-hour window. These findings demonstrate that adjusting sol-gel chemistry offers a powerful approach to control crosslinking degree and membrane morphology within the same hybrid system. This tunability expands the potential of these membranes for diverse tissue engineering applications, including scaffolds designed to match the distinct structural requirements.