Nano- and Micro-structuring of Materials Using Polymer Cold Drawing Process

Cold drawing is a well-established manufacturing process for tailoring properties of polymers in polymer industries. It refers to the phenomenon that necks formed during the tensile drawing of polymer fibers, films, or any other shapes. The necking reduces the height and width of the polymer sample being stretched and elongates it in length. The cross-sectional area in the necking region becomes smaller and keeps in a constant value with traveling to the remaining non-necking regions until the non-necking regions disappeared. Fundamentally, cold drawing is the movements and orientations of entangled polymer chains under external forces. It happens both for amorphous and for semicrystalline polymers in specific conditions. Though the cold drawing process has long been used in industrial applications, it has been rediscovered as a method of nano- and micro-structuring of materials recently. Materials used for structuring are wrapped in polymer fiber to form a core-shell structure or attached to the surface of the polymer substrate, then experience ordered fragmentations during the cold drawing of the composite structure, and finally formed regular patterns in nano- and micro-scale. This robust nano- and micro-structuring process is easy to perform and can be conducted using bare hands in some situations. Further, this method can be applied to various materials and is suitable for large-scale fabrication. This chapter discusses nano- and micro-structuring of materials including crystal, glass, and polymer with the core-shell structured fiber and film-based flat geometries.