Fundamentals of two-dimensional films and membranes

Abstract Biopolymer-based films and membranes have increasingly attracted interest in different areas, such as health, food, energy, and environment. Multidisciplinary research efforts have been focused to make these materials technically and commercially feasible. However, extensive use is still challenged by inherent limitations, such as brittleness, hydrophilicity, poor moisture and gas barrier, and inferior compatibility. In this chapter, general aspects of two-dimensional films and membranes using biopolymers as raw materials are addressed. The main processing methods to obtain dense (casting, coating, layer by layer, and extrusion) and porous (particulate leaching, thermally induced phase separation, and electrospinning) structures are introduced. Despite the wide variety of techniques available, most biopolymers will need to undergo matrix modifications to obtain the desired material processability and functional properties. These modification strategies based on plasticization, cross-linking processing with ionic liquids, blending, and composite formation are also discussed.