Nanolayer coextrusion process: principle and potentialities

Coextrusion is a process widely used in industry, which consists in combining the properties of several polymers in superimposed layers. In this conventional coextrusion process, the number of layers in the final object (film, sheet, foil, profile, tube) is between 2 and 11. A further development of this process involves the use of devices enabling a considerable increase in the number of layers, which can then reach several hundred or even thousands. For a given composition and thickness of the final object, an increase in the number of layers is accompanied by a reduction in their thickness, which can theoretically reach the nanometric scale when the number of layers is very high.

Research has shown that the resulting multi-nanolayer film can exhibit remarkable final properties, generated by confinement and/or interfacial phenomena. There may therefore be a major interest in reaching the nanometric scale for the thickness of these layers. This process, which originated in the industrial world and has been widely studied in academic circles for several decades, is now beginning to give rise to industrial applications. The improved properties resulting from this multilayer structure offer interesting potential for the manufacture of innovative materials with specific properties and increasingly stringent specifications. The aim of this article is to present the advantages of multi-nanocomponent structures and the principle behind the devices used to fabricate them. The potential of the process in terms of property enhancement, as well as its limitations, will be demonstrated.