## 3 Results and Discussion
The spectra are presented in Figure 8. The FTIR spectrum of the filament produced with pure E100 (E100 sample) exhibits characteristic vibration bands of the polymer (provided by the manufacturer) at 2954 cm\({}^{-1}\), 2770 cm\({}^{-1}\), 2873 cm\({}^{-1}\), 2820 cm\({}^{-1}\), 1729 cm\({}^{-1}\), 1460 cm\({}^{-1}\), 1385 cm\({}^{-1}\), and 1150 cm\({}^{-1}\). These vibrational bands are in agreement with results obtained in previous works in the literature (as detailed in Table 1). Figure 7: X-ray diffractograms (XRD) of the pristine Hesperidin (Hsp) and E100, E100/Hsp(\(-\)) and E100/Hsp(\(+\)) type filaments. obtained for the E100/Hsp-type filament samples were similar. In addition, the hybrid filaments present the stretching and bending vibrations of the separated materials before extrusion, indicating the viability of the production process for these composites, with combined characteristics of the polymer and the drug. In addition to the FTIR data, the attenuated total reflectance (ATR) method was used to verify the solubility of E100, E100/Hsp(\(-\)), and E100/Hsp(\(+\)) filaments when immersed in basic pH fluid (inset of Figure 8). The results of the analysis of the solution where the samples were immersed, after 60 min under constant agitation, showed the total absence of vibrational bands of the polymer and drug, across the entire wavenumber range studied (with negligible variation in transmittance intensity from 500 to 4000 cm\({}^{-1}\)). In fact, the E100 polymer is highly hydrophobic and this characteristic is already widely known in the literature for the synthesis of nanostructures to encapsulate drugs [17]. When immersed in fluids with basic pH, the E100-based filaments retain their chemical structure and their shape remains unchanged, without gaining mass and/or volume. The thermal analysis of the E100, E100/Hsp(\(-\)) e E100/Hsp(\(+\)) filaments and pristine Hsp were investigated based on the obtained DSC spectra (Figure 9). The E100, E100/Hsp(\(-\)), and E100/Hsp(\(+\)) DSC spectra of the filament samples display an endothermic peak at 56 \({}^{\circ}\)C, which corresponds to the glass transition point of the polymer [17; 26; 42]. In addition, the signal noted at 282 \({}^{\circ}\)C (for all three filament types) corresponds to the degradation temperature of the E100 [17]. The DSC spectrum of Hesperidin (Hsp) showed an endothermic peak at 263 \({}^{\circ}\)C, corresponding to the melting point of the drug, in agreement with data in the literature [43; 44; 45]. No signal of degradation of the Hsp molecule was detected in the temperature range analyzed, which endorses the thermal stability of the compound at the processing temperatures of the filaments. The DSC thermogram of pure Hsp also shows a smaller peak centered at 145 \({}^{\circ}\)C (not widely discussed in the literature), possibly due to its glass transition temperature occurring above 100 \({}^{\circ}\)C or to a dehydration process in the material [35; 46]. This temperature is shifted to 119 \({}^{\circ}\)C and 113 \({}^{\circ}\)C for the E100/(Hsp(\(-\)) and E100/(Hsp(\(+\)) filaments, respectively. These changes do not influence the usability of the drug for its intended purpose. The DSC spectra also highlighted that the melting point temperature of the Hsp molecules in the E100/(Hsp(\(-\)) and E100/(Hsp(\(+\)) filaments was shifted to lower temperatures (247 and 250 \({}^{\circ}\)C, respectively), with a lower intensity of the respective endothermic peaks.