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21.15 Product Class 15: Polyamides

DOI: 10.1055/sos-SD-121-00001

Higashihara, T.; Ueda, M.Science of Synthesis Knowledge Updates, (20104301.

General Introduction

Polyamides are defined as polymers containing amide linkages at monomer repeating units along main chains. They have been widely studied and commercialized since Ca­rothers of DuPont filed the first patents[‌1‌] in 1937 on synthetic polyamides, such as nylon-6,6, which is still one of the most important products and has a variety of uses. Poly­amides can be categorized into aliphatic (1), aliphatic–aromatic (2), and aromatic types (3) by the different sequences in their chemical structures, as shown in Scheme 1.

Scheme 1 Aliphatic, Aliphatic–Aromatic, and Aromatic Polyamides

Following the development of injection-molding, aliphatic polyamides have been widely used as engineering plastics. Aliphatic–aromatic polyamides have also been well studied and are of industrial importance. The later developed aromatic polyamides, the so-called super engineering plastics, are fiber-forming materials with the highest level of thermal stability found among organic polymers. Representative aromatic polyamides are poly­(m-phenylene isophthalamide) and poly(p-phenylene terephthalamide), which have the trade names Nomex and Kevlar, respectively.

Since there are many review articles on general synthetic approaches to poly­amides,[‌2‌‌7‌] this review emphasizes synthetic methods used to obtain aromatic poly­amides. It also focuses on recent advances in the formation of well-defined polyamides by condensative chain-growth polymerization, hyperbranched polymers by using ABx monomers, and dendrimers by divergent and convergent methods.