LAUSR

Abstract Three-dimensional (3D) printing has emerged as one of the most versatile and useful technologies for developing materials and products for virtually all applications. In addition to 3D printing technologies, the properties of materials selected for 3D printing are also critical and determine the applications of 3D printed structures. New and unique materials to meet specific requirements of 3D printing process and properties of products developed. Fortunately, materials used for 3D printing can be in solid, semisolid, and aqueous forms and range from particles, to filaments, and to hydrogels, and provide a plethora of choices to meet various needs. Compared to metals, carbon, and other sources, polymeric materials are ideal to meet the requirements of 3D printing. There are innumerable polymers and with considerable variations in their properties to meet the requirements to 3D printing. However, in addition to the polymers, the type of 3D printing process used affects the final properties of the products obtained. In this chapter, an overview of polymers in various forms used for 3D and to some extent four-dimensional printing are presented along with processing conditions used. The chapter has been broadly classified into biopolymers (both natural and synthetic) and conventional petroleum-based polymers. Since many researchers have used a combination of bio and synthetic polymers and several hybrid printed 3D materials are available, some overlap in the discussions is inevitable. Since polymers vary considerably in the structure and properties, and detailed reports are already available, we have not covered the properties of individual polymers but have rather focused on the properties of the 3D printed products. Also, this chapter does not cover the carbon and metallic-based materials used in 3D printing.