Transparent Pullulan/Mica Nanocomposite Coatings with Outstanding Oxygen Barrier Properties

Abstract

This study presents a new bionanocomposite coating on poly(ethylene terephthalate) (PET) made of pullulan and synthetic mica. Mica nanolayers have a very high aspect ratio (α) at levels much greater than that of conventional exfoliated clay layers (e.g., montmorillonite). A very small amount of mica (0.02 wt%, which is ϕ ≈ 0.00008) in pullulan coatings dramatically improved the oxygen barrier performance of the nanocomposite films under dry conditions, whereas this performance was partly lost as the environmental relative humidity (RH) increased. This outcome was explained in terms of the perturbation of the spatial ordering of mica sheets within the main pullulan phase because of RH fluctuations, as confirmed by modelling of the experimental OTR data according to Cussler's model. The presence of the synthetic nanobuilding block (NBB) led to a decrease in both static and kinetic coefficients of friction compared with neat PET (≈12% and 23%, respectively) and PET coated with unloaded pullulan (≈ 26% reduction in both coefficients). In spite of the presence of the filler, all of the coating formulations did not significantly impair the overall optical properties of the final material, which exhibited haze values below 3% and transmittance above 85%, with the only exception represented by the formulation with the highest loading of mica (1.5 wt%, which is ϕ ≈ 0.01). These findings revealed, for the first time, the potential of the NBB mica to produce nanocomposite coatings in combination with biopolymers for the generation of new functional features, such as transparent high oxygen barrier materials.

Effect of the hyaluronic acid‐poloxamer hydrogel on skin‐wound healing: in vitro and in vivo studies

“…A moisture permeability analyzer (Cat # Permatran‐W3/61, Mocon Corporation, Illinois, USA) was used to examine the water vapor transmission rate (WVTR, g/m 2 /day) of hydrogel . An oxygen permeability analyzer (Cat # 8001, Mocon Corporation, Illinois, USA) was used to examine the oxygen transmission rate (OTR, ccm/m 2 /day) of hydrogel . Test temperature ( T ) and relative humidity (RH) conditions were T = 25°C, RH = 0 for OTR measurement and T = 25°C, RH = 50% for WVTR measurement.…”

Nano-inspired oxygen barrier coatings for food packaging applications: An overview

“…1). On one hand, the reason probably lies in the increasingly recognized role of coating technology in pursuing the packaging optimization goal, i.e., down-gauging current packaging structures (e.g., laminates and/or co-extruded materials) without impairing (and, in fact, improving) the overall performance of the substrate beneath, at a reasonable cost (Uysal Unalan, Boyaci, Trabattoni, Tavazzi, & Farris, 2017). Nanoscience and nanotechnology, on the other hand, will make possible the creation of new functional coatings with previously non-achievable properties (Verma, 2017), with the goal of boosting the never-ending endeavor of meeting the market's needs.…”

“…Platy NBBs as alternative to montmorillonites were used for the development of oxygen barrier nanocomposite coatings intended for food packaging applications. Unalan et al, for example, tested the oxygen barrier performance of nanocomposite coatings obtained using GO and synthetic mica as fillers (Uysal Unalan, Boyaci, Ghaani, Trabattoni, & Farris, 2016;Uysal Unalan et al, 2017). The authors proved the outstanding performance of the nanocomposite coating under dry conditions (OTR values below the instrumental detection limit) for both fillers.…”