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In the beginning of the twentieth century, Hermann Staudinger formulated the hypothesis of the existence of very large macromolecules with high molecular weights (Mülhaupt 2004). This hypothesis was verified experimentally in the 1920s, when Theodor Svedberg and Lawrence Bragg proved that hemoglobin and cellulose consisted in macromolecules (Rånby 1995). The acceptance of the existence of macromolecules allowed the development of a myriad of polymeric materials, such as plastics, rubbers, paints, and varnishes, that are now part of our daily lives. In addition to intentional discoveries, such as nylon, polyesters, and isotactic polypropylene, there were also accidental discoveries, such as polyethylene and polytetrafluoroethylene. Today, new and interesting macromolecules are being created to obtain new mechanical, optical, and electrical properties.

The etymology of the word polymers comes from the Greek (poly meaning “many, several” and mers meaning “parts”), as the macromolecular architectures originate through the connection of several units of small molecules called monomers. Polymers are generally classified into synthetic and natural. Synthetic polymers are more frequent in our daily lives, being applied in many industrial sectors, agriculture, and services. These materials are of petrochemical origin (Figure 2.1), which represents about half of the chemical industry worldwide. The manufacture and transformation of petroleum into polymers guarantee the employment and support of millions of people, but also generate uncountable amounts of waste. It is estimated that 25 million tons of plastics are annually accumulated in the environment and due to the slow degradation rates, they remain unchanged for hundreds of years. The conversion of large pieces into smaller particles is an initial step of the degradation processes, which may cause contamination problems that directly impact the environment and health. In addition, polymers derived from fossil fuels put excessive pressure on nonrenewable energy sources (Andrady and Neal 2009; Rhodes 2018).

With sustainable development and due to the alarming pollution caused by nonbiodegradable materials, research institutes and companies from around the world have increasingly invested in the development and application of natural polymers to reach similar performances as those of synthetic origin.

Figure 2.1 Scheme of the productive chain of fossil‐based polymers.

Source: Based on Olivatto (2017).

The advancement of nanotechnology for the design of several biotechnological devices such as nanoparticles, nanofilms, and liposomes based on natural polymers has gained great scientific importance due to their ecofriendly properties and biocompatibility with living systems. The nanotechnological devices based on natural polymers have been highlighted particularly in the development of pharmaceutical systems for drug delivery, tissue engineering, and bioactivation mechanisms. The low or no‐toxicity and safety of natural polymers are essential characteristics for the use of these nanodevices in health, as will be discussed in this chapter.