What term refers to durable materials based on long chains of repeating molecular units?

The term that accurately describes durable materials made from long chains of repeating molecular units is polymers. Polymers consist of large molecules formed through the polymerization process, where small molecular units called monomers link together to create extensive macromolecules. This structure imparts a wide range of properties to polymers, such as flexibility, resilience, and lightweight characteristics, making them suitable for various applications in engineering, robotics, and materials science.

While plastics are indeed a subset of polymers, not all polymers are considered plastics. For instance, some polymers may remain in a rigid or non-plastic form. Metals and ceramics, on the other hand, have fundamentally different atomic structures and bonding characteristics, focusing instead on metallic bonds and ionic/covalent bonds, respectively, rather than molecular chains. Thus, 'polymers' is the most accurate and encompassing term for this concept.