Synthetic polyamides were developed as alternatives to the textiles wool and silk. Silk is a polymer of the amino acids glycine and alanine, whereas wool is more complex, having disulphide (sulphur-sulphur) bonds to link the polymer chains together. The sulphur is present due to the amino acid cysteine:



Polyurethanes

These polymers have a similar structure to the polyamides, which have the urethane (carbamate) group as part of the polymer backbone.