Synergistic Enhancement of Oxygen Barrier and Antioxidant Properties in Polyethylene Films via Polyvinyl Alcohol Coating With Modified Layered Double Hydroxide and Tannic Acid for Advanced Food Preservation

Packaging plays a critical role in ensuring food safety and shelf life by protecting against e.g., moisture, gases, and light. Polyethylene (PE) is widely used in food packaging, but it is mainly produced from non-renewable resources and it is an inefficient oxygen and light barrier. In this study, the layer-by-layer (LbL) assembly of a sustainably produced lignin-based polymer (EH) with polyethylenimine (PEI) or chitosan (CH) was used to fabricate (partially or fully) bio-based coatings with the aim of improving barrier properties of PE films. The charge density of EH was calculated using a polyelectrolyte titration method and the hydrodynamic diameters of EH, PEI and CH were determined by Dynamic Light Scattering (DLS). LbL assembly was monitored in situ via Quartz Crystal Microbalance with Dissipation (QCM-D) and Stagnation Point Adsorption Reflectometry (SPAR). PE films were coated with a variable number of PEI/EH or CH/EH bilayers (BL) using an immersive LbL assembly method. Coated films were studied in terms of light-blocking ability, wettability, thermal behaviour, surface structure, as well as oxygen and water vapor barrier properties. QCM-D and SPAR data showed a stepwise multilayer formation and strong interactions between the oppositely charged polymers, with PEI/EH coating having a greater amount of deposited polymer compared to CH/EH coating at the same number of BL. Overall, light barrier properties and wettability of the coated films increased with the number of deposited bilayers. Coated PE films maintained the overall thermal behaviour of PE. A number of BL of 20 was found to be the most promising based on the studied properties. Selected samples showed improved oxygen and water vapor barrier properties, with PEI/EH coating performing better than CH/EH coating. Taken altogether, we demonstrated that a novel and sustainable lignin-based polymer can be combined with PEI or CH to fabricate (partially or fully) bio-based coatings for food packaging.

Polyvinyl alcohol (PVA) has been widely applied in industries for its low cost, nontoxicity, biodegradability, and renewable advantages. However, its unstable structure may not meet some strong physical and mechanical needs. In order to enhance the performances of the PVA film, cellulose nanocrystals (CNCs), tannic acid (TA), and chitosan (CS), working as a reinforcer, a crosslinker, and an antimicrobial agent, respectively, were introduced into the PVA matrix. The results indicated that CNCs, TA, and CS were evenly distributed and cohesively incorporated within the PVA matrix, which contributed to the good mechanical properties and thermal stabilities of biocomposite PVA films. Besides, the addition of TA remarkably improved the antiultraviolet and antioxidant capabilities of PVA films, although the light transmittance declined slightly. It was also observed that the pure PVA film and PVA reinforced with CNCs were incapable of protecting against bacteria, while the ones with CS had prominent antibacterial properties to Escherichia coli and Staphylococcus aureus. Overall, the resulting film presented a high potential utilization as a food packaging material for its outstanding physical and mechanical performances.

High-performance carboxymethyl cellulose-based hydrogel film for food packaging and preservation system

Improving barrier and antibacterial properties of chitosan composite films by incorporating lignin nanoparticles and acylated soy protein isolate nanogel

This study investigates the synergistic effects of incorporating layered double hydroxide (LDH) and tannic acid (TA) into polyvinyl alcohol (PVA) films to enhance their mechanical, tribological, and corrosion resistance properties for biomedical applications. Composite coating films were prepared by blending PVA with LDH and TA in various concentrations. The addition of LDH and TA significantly increased the crystallinity index of the composite films, with the highest crystallinity observed at 66.3% for the sample containing 1 wt% TA and 2 wt% LDH (PVA/TA1/LDH2). This enhancement in crystallinity contributed to improved mechanical performance, as demonstrated by tensile tests, where the PVA/TA1/LDH2 composite exhibited the highest tensile strength among all samples. Tribological testing revealed that the PVA/TA1/LDH2 composite also achieved the lowest coefficient of friction (COF), along with a minimal wear rate, indicating superior wear resistance. SEM analysis of the wear scars confirmed a narrow wear track and smoother surface morphology for this composite, which suggests effective load distribution and reduced surface degradation. The addition of TA was further shown to improve the corrosion resistance of the PVA composite films, with the PVA/TA1/LDH1 sample exhibiting the lowest corrosion current density (Icorr) of 0.36 μA cm−2, representing a significant improvement over neat PVA. These findings highlight the potential of PVA/LDH/TA films for coating applications in biomedical devices, where enhanced mechanical strength, wear resistance, and corrosion protection are critical. The synergistic effects of LDH and TA provide a pathway for developing durable and functional coatings, expanding the practical utility of PVA films in demanding biomedical environments.

Surfactants used to exfoliate and disperse nanoparticles are expected to have an impact on polymer nanocomposite properties. In this work, both ionic tetrabutylammonium hydroxide (TBA) and amphiphilic polyoxyalkyleneamine (M1000) surfactants were used to exfoliate α‐zirconium phosphate (ZrP) in polyvinyl alcohol (PVA) matrix through simple solution blending. The oxygen barrier properties of the nanocomposites were investigated as a function of ZrP content based on the above two surfactant types. At a low ZrP loading level (≤2.4 vol%), regardless of the surfactant type, the ZrP nanoplatelets in PVA matrix do indeed create a “torturous pathway” to improve barrier properties even though the crystallinity in PVA/ZrP‐M1000 system is decreased. In addition, the PVA/ZrP‐TBA films exhibit excellent transparency as good as the neat PVA films. Furthermore, it is found that the high molecular weight amphiphilic M1000 surfactant is less effective than the low molecular weight ionic TBA surfactant in dispersion and exfoliation of ZrP in PVA. This relative incompatibility of ZrP‐M1000 compared to ZrP‐TBA in PVA leads to its dramatic drop in oxygen barrier properties. This facile aqueous solution blending technique is eco‐sustainable and expected to facilitate the preparation of effective polymer nanocomposites for barrier properties applications.

One-step assembly of poly(vinyl alcohol)/tannic acid complexes as a high oxygen barrier coating for poly(lactic acid) packaging films

Tunable biocomposite films fabricated using cellulose nanocrystals and additives for food packaging

Two current consumer demands will shape the future of food packaging: the demand on minimally processed and preservative-free foods, and the demand on environmental friendly packaging materials. In order to produce preservative-free foods but maintain same food safety, an alternate method is to incorporate antimicrobial agents (AM) into packaging materials, called antimicrobial food packaging. On the other hand, biodegradable polymers from renewable resources can to some extent reduce food packaging waste. To response these demands, bio-based antimicrobial films were developed in the present study. In particular, two antimicrobial agents, sodium benzoate (Bz) and natamycin (Nat), were incorporated into starch to form starch-based films. Furthermore, two incorporation methods were studied, one was directly incorporating antimicrobial agents into starch matrix, and the other was incorporating antimicrobial-nanoparticle systems into starch matrix. In the latter method, AM were first loaded onto nanoparticles, layered double hydroxide (LDH), called LDH-Bz and LDH-Nat, and then incorporated into starch. Five starch-based films were prepared: starch without AM as control, starch with sodium benzoate, starch with natamycin, starch with LDH-Bz, and starch with LDH-Nat. Mechanical and barrier properties of the films were studied. The results showed that addition of antimicrobial agents has significant effect on elongation at break but no significant effect on tensile strength. The elongation increased from 6.75% for control film to 17.69% for film with 2% of LDH-Bz. Three permeabilities (water, oxygen, and CO2) were significantly decreased while AM incorporated. However, the different incorporation methods did not show effect on neither mechanical nor barrier properties.

In this work, metal/semiconductor nanocomposites/metal devices with aluminium (Al) as top electrode (TE) and bottom electrode (BE) were fabricated and investigated using ZnO nanoparticles (ZNPs) embedded in an insulating polyvinyl alcohol (PVA) matrix for non-volatile memory applications. The I-V measurements of Al/ZnO-PVA/Al device exhibited a non-volatile bistable resistive switching behaviour. The switching mechanism of the device was suggested by the models of trap controlled space-charge limited conduction (SCLC) and the charges trapping-detrapping process at the centers of ZNPs in the PVA matrix. The state of the device was maintained even after removal of the applied bias, indicating the non-volatile bistable memory. There was no remarkable degradation of the device in both the LRS and the HRS after 30 minutes continuous operation which demonstrated excellent stability of the device. The current ratio of high resistance state (HRS) to low resistance state (LRS) is about of the order of 102 at room temperature. This demonstration provides a class of memory devices for non-volatile bistable memory device applications.

Development of chitosan-based antibacterial and antioxidant bioactive film incorporated with carvacrol-loaded modified halloysite nanotube

Tartaric acid-crosslinked chitosan-based quaternary ammonium/phosphonium salt-PVA multifunctional composite films for enhanced food preservation.

This study explores the combined use of plasma-activated water (PAW) washing and clay nanocomposite polyethylene (NCPs-PE) films to enhance the postharvest preservation of sweet lemons over five months under ambient storage. Structural analyses (FTIR, XRD, SEM, AFM and, EDS) confirmed successful incorporation of clay nanoparticles into the PE matrix, resulting in intercalated nanocomposite structures, homogeneous surface morphology, and good filler-polymer compatibility. The NCPs-PE films exhibited higher moisture content (MC), water vapor permeability (WVP) than pure PE, while water vapor transmission rate (WVTR) remained unchanged at p < .05. The films demonstrated superior antifungal activity against Penicillium digitatum (inhibition zone = 30 mm) and reduced decay rates compared to neat PE. Fruits packed with NCPs-PE showed the lowest decay rate (33%), while PAW washing combined with PE packaging resulted in minimal weight loss (3.18 ± 0.26 g) and optimal firmness (1.92 ± 0.02 N). Overall, the synergistic effect of nanocomposite packaging and PAW treatment effectively limited microbial growth, maintained fruit quality, and extended shelf life, indicating the potential for sustainable citrus preservation, though further optimization is needed for commercial application.

Design and preparation of gels with excellent mechanical properties has garnered wide interest at present. In this paper, preparation of polyvinyl alcohol (PVA)-tannic acid (TA) gels with exceptional properties is documented. The crystallization zone and hydrogen bonding acted as physical crosslinkages fabricated by a combination of freeze-thaw treatment and a tannic acid compound. The effect of tannic acid on mechanical properties of prepared PVA-TA gels was investigated and analyzed. When the mass fraction of PVA was 20.0 wt% and soaking time was 12 h in tannic acid aqueous solution, tensile strength and the elongation at break of PVA-TA gel reached 5.97 MPa and 1450%, respectively. This PVA-TA gel was far superior to a pure 20.0 wt% PVA hydrogel treated only with the freeze-thaw process, as well as most previously reported PVA-TA gels. The toughness of a PVA-TA gel is about 14 times that of a pure PVA gel. In addition, transparent PVA-TA gels can effectively prevent ultraviolet-light-induced degradation. This study provides a novel strategy and reference for design and preparation of high-performance gels that are promising for practical application.

The effects of ozone (O3) gas exposure at various concentrations and treatment times on structural, mechanical and barrier properties of polyethylene and polyamide films were investigated. Changes in the structure of the films were monitored using an FT‐IR spectrometer. The results showed that O3 treatment affected polyethylene and polyamide films differently. While O3 treatment caused formation of oxygen‐containing functional groups and degradation of polymeric chains in polyethylene films, O3 treatment of polyamide films significantly increased the –C–N– stretch observed at 1125 cm−1 in the FT‐IR spectra. The changes in the mechanical properties of polyethylene films depended on the O3 treatment conditions (temperature and O3 concentration were the most significant), but an increase in tensile strength of polyamide films was observed regardless of the treatment conditions. Permeability to O2 for both types of films decreased with increasing O3 treatment time. Copyright © 2003 John Wiley &amp; Sons, Ltd.