Micro- and nano-layered processing of new polymeric systems

Recent progress on polymeric hierarchical systems fabricated by forced assembly multilayer coextrusion technology is presented. Complicated polymeric hierarchies are fabricated by this novel layer multiplication method through a solvent-free, continuous and flexible process. Superior properties have been achieved in coextruded polymeric systems by manipulating their microstructure under the guidance of “three rules” that are derived from hierarchies that underly the function of many biological materials. These are the scale, the interaction, and the architecture of the structural levels. The polymeric hierarchies have structural scales ranging from microns to nanometers and are fabricated into distinct architectures including layered films, cellular film/foams, fibrous membranes and gradient structures by this novel multilayer coextrusion process. These coextruded polymeric systems with well-controlled hierarchical structures exhibit significantly improved properties over the conventional polymeric composites. Applications that are enabled by multilayer coextrusion technology are comprehensively reviewed, including gas barrier films for packaging, optical films for lasers, information storage and gradient refractive index (GRIN) lens, dielectric films for capacitors, shape memory films for actuators and anti-counterfeiting, film/foams for high-performance light-weight media, and fibrous membranes for filtration and bio-medical substrates. The translation of the layered GRIN lens and dielectric film capacitor technologies from laboratory research to commercial production is also presented.