## 4 Discussion
However, electrospinning of pure SA presents inherent difficulties, due to the stiff molecular structure of the SA, the high electrical conductivity of the SA aqueous solution resulting from its polyelectrolyte nature, and the formation of SA intra- and inter-molecular hydrogen bonds. These aspects contribute to the high-surface tension of SA, making the electrospinning process challenging [38]. Although the literature lacks reports of successful electrospinning of aqueous solutions of pure SA, some studies have employed co-solvents or carrier polymers to address this issue [38; 39; 40]. [PERSON] et al. demonstrated the production of uniform SA fibers in the submicron range using glycerol as a strong polar co-solvent [40]. Glycerol ability to enhance the entanglements of SA chains by forming new hydrogen bonds, proved crucial in improving the electro-spininability. However, this approach had limitations, including the presence of spherical clusters on the fiber surface and wide diameter distributions. The other well-explored approach to facilitate SA electrospinning process involves the incorporation of hydro-soluble polymers, such as PVA and PEO, as carrier materials [35]. [PERSON] et al. investigated SA/PEO blends and found that PEO played a pivotal role in enhancing electrospinning by increasing viscosity and relaxation time, while lowering the conductivity and surface tension of the solution [39]. To achieve uniform fiber formation, a minimum PEO molecular weight of 600 kDa was required, while a higher molecular weight PEO (i.e., 1000-2000 kDa) enabled the production of fibers with greater SA content and larger diameters. The addition of 1% Triton X-100, a non-ionic surfactant, revealed to be beneficial to improve SA content, reaching a maximum of 85%. In this research, SA electrospinningming challenges were addressed by utilizing high molecular weight PEO (i.e., 1000 kDa) as a support polymer, ensuring high SA content in the resulting fibers (i.e., 7 \(w\)% SA51 MG03 + 3 \(w\)% PEO). To further enhance the electrospinningmability and promote defect-free structure formation, Triton X-100 was also introduced. The successful electrospinningming of SA/PEO solution was corroborated by the results of the rheological studies, which had a weak shear-thinning behavior, crucial for preventing the disruption of entanglements and promoting fiber elongation during the electrospinningm process. The Hagen-Poiseuille equation calculated a shear rate within the Newtonian region, further underscoring the suitability of this approach [26]. The SA/PEO solution yielded continuous ultrafine fibers, with diameters of 264 \(\pm\) 95 nm and 281 \(\pm\) 79 nm, when collected at rotation speeds of 60 rpm and 1500 rpm, respectively. Optimal fiber morphology was best maintained when crosslinking was carried out by mixing 2 \(w\)/\(v\)% CaCl\({}_{2}\) in a 30/70 \(v\)/\(v\)% ethanol/dH\({}_{2}\)O reticulation bath. Since the crosslinking solution was water based, PEO could be dissolved, allowing the fabrication of SA fibers. However, the fiber diameters increased (i.e., 404 \(\pm\) 10 nm and 434 \(\pm\) 92 nm for collection speeds of 60 rpm and 1500 rpm, respectively). This outcome is consistent with evidence reported in the literature, where the simultaneous and competing influence of PEO removal and SA crosslinking gave rise to an overall increase in fiber size [41]. Furthermore, the presence of ethanol in the crosslinking bath expedited the crosslinking of SA fibers, by accelerating the formation of solid fiber mashes while also enhancing the fibers' swelling behavior [42; 43; 44]. After 24 h in DPBS, a remarkable increase in fiber diameters was observed (i.e., 853 \(\pm\) 22 nm and 666 \(\pm\) 14 nm for collection speeds of 60 rpm and 1500 rpm, respectively). This phenomenon can be attributed to the swelling behavior of the fibers combined with the morphological changes that occurred after crosslinking.