## 2 Materials and Methods
### Production and Characterization of Nanocellulose Films  
The nanocellulose films were produced using the solvent casting methodology. Initially, the diluted nanocellulose suspensions (1%, \(w\)/\(w\)) were mixed with glycerol (25%, \(w\)/\(w\) in relation to nanocellulose) as the plasticizer. This procedure was performed at room temperature for 15 min, maintaining stirring at 300 rpm. For better homogenization, the mixture was taken to the Ultra-Turrax (IKA, Staufen, Germany) for 2 min at 6000 rpm. Subsequently, to eliminate the air created during this process, the blend was placed in a low pressure rotavapor for approximately 30 min. Finally, the mixture was poured into Petri dishes and dried at 60 \({}^{\circ}\)C for 6 h in an oven with air circulation. The films were then stored at 50 \(\pm\) 3% RH and 23 \(\pm\) 2 \({}^{\circ}\)C for further characterization. For the wax coating, 3 mg of extracted wax was mixed with 4 g of dichloromethane in a test tube placed in a polyethylene glycol (Merck, Darmstadt, Germany) bath at 30 \({}^{\circ}\)C for 90 min. Subsequently, molten wax was applied to the surface of nanocellulose films (0.2 g) with a heated glass rod. To ensure the uniform application of wax onto the film surface, the film was placed on a preheated glass plate. A small volume of wax solution was then poured along one edge of the film, and a preheated glass rod was used to spread the wax while applying light and even pressure. The single-sided wax-coated films were dried at room temperature and afterward characterized. For this purpose, structural properties, transparency, contact angle, surface energy, water vapor permeability, FTIR and DSC tests were performed. Regarding the structural properties of the films, specifically grammage, thickness and density were evaluated. Grammage was assessed by the mass-to-area ratio (g.m\({}^{-2}\)) following the ISO 536:1995 standard [13]. Thickness (\(\upmu\)m) was measured on a digital micrometer, Adamel Lhomargy (model MI 20) (Saint Baldoph, France), following the ISO 534:2011 standard [14], obtaining five random readings for each film. Following the same standard protocol, the density (g.cm\({}^{-3}\)) of the films was determined by the ratio between grammage and thickness. Transparency was accessed on the Technidyne Color Touch 2 spectrophotometer, (Technidyne, New Albany, IN, USA) following the ISO 22891 standard [15], using the D65 illuminant and the 10\({}^{\circ}\) observer. Two measurements were taken for each type of film. Contact angle measurements were made by applying the sessile drop method on an OCAH 200, DataPhysics Instruments (DataPhysics, Filderstadt, Germany). At least six measurements were performed for each film. Three reference liquids (deionized water, ethylene glycol and diiodomethane) were used to estimate the surface free energy of the films (total, dispersive and polar components) following the Owens, Wendt, Rabel and Kaelble (OWRK) approach [16]. To assess water vapor barrier properties, the desiccant method of ASTM E96-22 standard [17] was followed at 23 \(\pm\) 2 \({}^{\circ}\)C and 50 \(\pm\) 3% RH. Firstly, WVTR was evaluated and afterward the water vapor permeability (WVP) of the films was determined. For this purpose, using an analytical balance, weight changes (\(\Delta\)w) were recorded over a period of 48 h every 2 h. After that, the graph of mass variation as a function of time allowed the assessment of the slope of the straight line (\(\Delta\)w/\(\Delta\)t). The WVTR was reached through the quotient between this value and the exposed sample area (m\({}^{2}\)). Lastly, the WVP was determined using the WVTR values multiplied by the film thickness and dividing by the vapor pressure on each side of the film. Two replicate samples were carried out. This method measured the amount of water vapor that diffused through the film and was absorbed by the desiccant placed beneath it. The water vapor that permeated the film was achieved by the increase in mass of the desiccant.