Method and apparatus for producing a high aspect ratio nanostructured foil by extrusion coating or extrusion casting

A method for producing a nano- or micro-structured thermoplastic foil comprising at least one nano- or micro-structured surface area, comprising:

• providing an extrusion casting roller for an industrial polymer extrusion casting process using a thermoplastic material;
• applying a nano- or micro-structured surface on said extrusion casting roller thereby forming a nano- or micro-structured extrusion casting roller;
• maintaining a temperature of said nano- or micro-structured extrusion casting roller below a solidification temperature of said thermoplastic material, wherein said nano- or micro-structured extrusion casting roller is rotating;
• continuously applying a melt of said thermoplastic material between a counter roller and said nano- or micro-structured extrusion casting roller while said nano- or micro-structured extrusion casting roller and said counter roller are rotating;
• and
• moving the melt of said thermoplastic material between said nano- or micro-structured extrusion casting roller and said counter roller at a given velocity corresponding to a rotational velocity of said nano- or micro-structured extrusion casting roller while said nano- or micro-structured extrusion casting roller and said counter roller are rotating, wherein said velocity of said melt of said thermoplastic material and the rotational velocity of said nano- or micro-structured extrusion casting roller is higher than 10 meters per minute;
• wherein said melt of said thermoplastic material is solidified upon contact with said nano- or micro-structured extrusion casting roller maintained at the temperature below the solidification temperature of said melt of said thermoplastic material thereby forming a solid nano- or micro-structured thermoplastic foil.