*2.8. Mechanical Strength*

The mechanical strength of the nanofibrous films was measured through a mechanical testing instrument (Instron 5944, Norwood, MA, USA) quipped with a loadcell of 10 N used at ambient temperature. The force rate was 1 mm min−1. The films were tailored into strips with a thickness of 0.1 mm.

#### *2.9. Water Contact Angle (WCA)*

A OCA20 device (Data Physics Co., Ltd., Bad Vilbel, Germany) was employed to investigate the WCA of the nanofibrous films through the sessile drop method [32]. The nanofibrous films were fixed on the object slides, and then a droplet of distilled water (3.5 μL) was deposited on the nanofibrous films. The water drops at 0 and 3 s were both recorded and averaged to determine the values of the WCA. The WCA value was computed from three positions on the films [33].

#### *2.10. Water Vapor Permeability (WVP)*

The ASTM E96 gravimetric method was used to calculate the WVP values. Fibrous film was fixed on top of a permeation cup filled with distilled water and kept in a desiccator loaded with dry silica gel. Following the attainment of steady state (approximately 1 h), the permeation cups were weighed every 12 h during a 5-day period. The WVP was obtained according to the following Equation [34]:

$$\text{WVP} = \frac{\Delta M \times d}{\Delta t \times A \times \Delta p} \tag{1}$$

where Δ *M*/Δ*t* is the weight of water loss per unit time (g <sup>h</sup>−1), *d* is the film thickness (mm), *A* is the area of the film exposed to moisture (m2), and Δ*p* is the water vapor pressure difference crossing the film (3.1671 kPa at 25 ◦C), respectively.
