Atomic Layer Deposition of Thin Inorganic Coatings onto Renewable Packaging Materials

Abstract

Biopolymers play still a relatively minor role in the packaging material markets. For this to grow further there are problems to be solved, such as inadequate barrier properties and moisture sensitivity. Atomic layer deposition (ALD) is one potential solution. Atomic layer deposition is a layer-by-layer thin film deposition process based on self-limiting gas-solid reactions. It is well suited for producing pinhole free barrier coatings uniform in thickness at relatively mild process conditions. The purpose of this presentation is to summarize our recent work done concerning atomic layer deposition of thin aluminum oxide layers onto biopolymers.

Bio‐based multilayer barrier films by extrusion, dispersion coating and atomic layer deposition

“…Extrusion coating of bio‐LDPE with high melt temperatures and low coating speed can have a detrimental effect on the bio‐HDPE surface onto which the thin Al 2 O 3 coating was deposited. Different thermal expansion between the layers or even melting of the bio‐HDPE surface may have damaged the oxide film, which also explains why in some cases ALD‐coated polyethylene surfaces can be heat sealed against each other . In most cases, dry or solvent‐free lamination would actually be a more feasible laminating process typically used for metallized and other metal oxide coated plastic films.…”

“…However, recently there have been an increasing number of activities related to roll‐to‐roll and atmospheric ALD processes . A thin ALD coating does not impair disintegration of PLA film or coated board in compost, and polymer granules deposited with such coatings have been melt processed into composites indicating certain level of recyclability …”

“…It is well suited for producing inorganic moisture and gas barrier coatings, such as Al 2 O 3 , SiO 2 , and ZnO, onto petroleum‐ and bio‐based polymers . However, inorganic oxide coatings with thickness of tens of nanometers are sensitive toward mechanical stresses, and they in most cases require tailored inorganic/organic hybrid multilayer structure preferably with a protective polymer coating layer . A protective heat sealing layer can, for example, be applied in a subsequent extrusion coating process.…”

Sustainable biodegradable coatings for food packaging: challenges and opportunities

“…• Pinhole-free and uniform high barrier coatings and can provide chemical resistance and stress relaxation 35,251,252 • Toxic gas can possibly be released from the reaction 47 • High deposition rate and low deposition temperature 47 • Substrate temperature may cause phase changes or grain growth and diffusion of dopants in microelectronic components 47 • CVD is the most popular method to obtain highly uniform coatings on 3-D substrates 47 • The corrosive gas can lead to poor adhesive between coated film and substrate and contaminate the film 47 • CVD provide multidirectional deposition 253 • Pricey vacuum environment and expensive instrumentation 245 • PVD provides full control over growth, pristine film quality, large-scale fabrication, co-deposition flexibility, and controlling of the deposition temperature 253 • PVD provide only linear type of deposition 253 a Although this is true for generally solvent-based coatings methods, the thermoplastic polymer used in the coating can influence the required coating weight. For example PLA coating by extrusion or solvent coating requires high coating weight to obtain necessary barrier properties, while solvent or dispersion coating of other biopolymers need lower coat weight to get sufficient barrier properties.…”

Pd Nanoparticles Loaded on Ceramic Membranes by Atomic Layer Deposition with Enhanced Catalytic Properties

“…Atomic layer deposition (ALD) for membrane-forming technology alternately pulses the vapor into the reaction chamber and allows the target species chemisorb on the surface of the carrier. , ALD has been widely used in microelectronics, − optoelectronics, − nanotechnology, , batteries, energy, organic electronic packaging, , separation membranes, , electrocatalysis, and organic pollutant degradation . In recent years, a large number of catalytic materials have been prepared by ALD.…”