Oxygen Gas and UV Barrier Properties of Nano-ZnO-Coated PET and PHBHHx Materials Fabricated by Ultrasonic Spray-Coating Technique.

Mohsin Abbas,Naveen Reddy,Wim Deferme,Mieke Buntinx,Roos Peeters

doi:10.3390/nano11020449

Mohsin Abbas, Naveen Reddy + Show 3 more

Open Access

https://doi.org/10.3390/nano11020449

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Journal: Nanomaterials	Publication Date: Feb 10, 2021
Citations: 8	License type: CC BY 4.0

Affiliation: Hasselt University, IMEC

Abstract

Ultrasonic spray-coating (USSC)—a wet chemical deposition method to deposit ultrathin (down to 20 nm) coatings—is being applied as a promising alternative deposition method for functional coatings due to an economical, simple, and precise coating process with easy control over its operating parameters. In this research, zinc oxide nanoparticles (ZnO NPs) were ultrasonically spray-coated on commercial-grade polyethylene terephthalate (PET) and poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBHHx) films. The most suitable parameters for the ink composition, the ultrasonic spray-coating process, and the number of coating passes (up to 50×) were selected on the basis of a series of experiments. The oxygen gas barrier properties in terms of the oxygen transmission rate (OTR) of neat PET, and 3×, 5×, 10×, and 50× ZnO NP-coated PET and PHBHHx substrates were investigated. The OTR values for neat PET, and 3×, 5×, and 10× ZnO NP-coated PET substrates were found to be the same; however, a 5% reduction in OTR for 50× ZnO NP-coated PET substrate was observed compared to the neat PET substrate. No reduction in OTR was found for any above number of coating passes on PHBHHx substrates against the neat PHBHHx substrate. However, the ultraviolet (UV) tests of 3×, 5×, and 10× ZnO NP-coated PET and PHBHH× substrates revealed a significant decrease in percentage transmission for 10× coated PET and PHBHHx substrates as compared to their 3× and 5× ZnO NP-coated substrates, respectively. It was revealed from the study that the 50× ZnO NP coating of the PET substrate created a slight difference in OTR as compared to the reference substrate. However, the ultrasonic spray-coating method created a significant UV barrier effect for 3×, 5×, and 10× ZnO NP-coated PET and PHBHHx substrates, which demonstrates that the optimized coating method cannot be used to create a high oxygen barrier but can certainly be applied for UV barrier applications in food packaging. It is concluded that ultrasonic spray deposition of ZnO NPs on PET and PHBHHx materials has shown promising results for UV barrier properties, demonstrating the advantages of using this method compared to other coating methods with regard to cost-effectiveness, precise coating, and better process control.

Highlights

This article is an open access articleIn the field of food packaging, nanomaterials are creating an incredible impact by improving the multifunctional properties of packaging films [1]
Many reports focused on applications of nanomaterials concerning food quality assurance and improvements in food packaging [2,3,4,5,6]
In the first approach, packaging films consisting of zinc oxide nanoparticles (ZnO NPs) along withpolymers have been made through diverse processing techniques, such as melt compounding [12], solvent casting [13,14], twin-screw extrusion [15], solution casting [16,17,18,19], and extrusion blow molding [20], leading to the evaluation of their gas barrier and mechanical properties

Summary

Introduction

This article is an open access articleIn the field of food packaging, nanomaterials are creating an incredible impact by improving the multifunctional properties of packaging films [1]. These nanoparticles have been utilized due to their antimicrobial activity [8]. Copper (Cu) and copper oxide (CuO), cadmium (Cd), zinc oxide (ZnO), magnesium oxide (MgO), and single-walled carbon nanotubes (SWCNTs) are reported for their antimicrobial activity [9] Amongst these nanoparticles, ZnO NPs have achieved a significant position in enhancing the packaging properties such as mechanical, barrier, and antimicrobial properties [10]. As far as the second approach is concerned, coatings in the packaging sector have shown incredible growth in recent years This has become possible due to two main factors: (1) increased accessibility of various types of nanoparticles, and (2) progress and innovations in the processes capable of controlling the coating structure. Nanocoatings have proven to be incredibly pertinent in surface functionalization to provide essential properties such as gas barrier [24], antimicrobial [25], flame retardant [26], and self-healing [27] properties

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