*2.2. Electrospinning and Meshes Characterization*

Fibers were electrospun using a set-up with the climate-controlled chamber (IME Technologies, Waalre, The Netherlands) at T = 25 ◦C and H = 40%, then deposited on the slowly rotating (10 rpm) collector covered with an Al foil; see the schematic in Figure 1. Three different fiber mats were produced: PS, PA6, and PS-PA6. For the first two mats, only one nozzle was used. High voltage with positive voltage polarity in the range of 13–20 kV was applied to the needle kept at a distance of 15–22 cm from the collector, with all the other parameters listed in Table 1. The quality of the electrospun fibers was analyzed with the scanning electron microscope (SEM, Merlin Gemini II, Zeiss, Oberkochen, Germany) after the samples were sputtered with gold (Q150RS, Quorum Technologies, Laughton, UK). The diameters of the fibers were measured using ImageJ (v1.51s, USA), and the average fiber diameter was calculated from 100 measurements in the SEM images. Additionally, the contact

angles were measured on the electrospun mats using deionized water. Pictures of water droplets were taken with a Canon EOS 700D camera (Tokyo, Japan) with an EF-S 60 mm f/2.8 Macro USM zoom lens 3 s after placing the 3-μL droplets on the mats. The contact angles were measured using MB-Ruler (version 5.3, Germany) based on the sessile drop method and the mean value was calculated as the average of 10 droplets. The roughness of the electrospun samples was analyzed in our previous reports [38], where a laser microscope (Olympus OLS4000, Tokyo, Japan) was used. Prior to the roughness analysis, the electrospun samples were deposited on glass slides and covered with the 5-nm gold layer. Ten measurements per sample type were performed, with the investigated area of <sup>646</sup> <sup>×</sup> <sup>646</sup> <sup>μ</sup>m<sup>2</sup> for PS and PS-PA6 composites, and 130 <sup>×</sup> <sup>130</sup> <sup>μ</sup>m2 for PA6.

**Figure 1.** The electrospinning set-up consisting of two nozzles to produce polystyrene (PS) and PS with nylon 6 (PA6) fibers at the same time to obtain the composite meshes.

**Table 1.** Electrospinning parameters of PS, PA6, and with two nozzles spinning at the same time to produce PS-PA6 composite meshes.

