Atomic Layer Deposited Nanoscale Coatings for Polymer Films

Atomic layer deposition (ALD) is a layer-by-layer deposition process based on repeated self-limiting gas-solid reactions by using volatile precursors. It is suited for producing dense and pinhole-free inorganic nanoscale coatings uniform in thickness at relatively low temperatures. The purpose of this presentation is to demonstrate the potential and the challenges of using ALD to create functional coatings for polymer films. ALD is an efficient tool for improving the barrier properties of polymer films. However, adequate barrier properties are only one of the key requirements set for the packaging materials. As far as safety issues are concerned, these coatings, for example, seem not to fall under the European definition of nanotechnology and migration is low enough to meet the requirements set by current European regulations. ALD can also be used to create antimicrobial coatings, and thin oxide coatings can be modified for improved mechanical and surface properties. It is recommended that ALD coatings are protected with an additional polymer layer providing also heat sealability. Although ALD is today carried out in batch mode, the development of roll-to-roll processes will enhance the feasibility of ALD for e.g. packaging materials