The Relationship Between the Structure and Properties of Amino Acid Surfactants Based on Glycine and Serine

Two series of surfactants based on glycine and serine were synthesized with aproic acid, octanoic acid, decanoic acid, dodecanoic acid, tetradecanoic acid and hexadecanoic acid. All the surfactants were characterized by MS and H-1 NMR, the structures of the synthesized surfactants are correct and the signals in MS and H-1 NMR can be explained. The reaction conditions, surface properties and foam properties were studied. For the two series of surfactants, critical micelle concentration (CMC) and gamma (CMC) (surface tension at CMC) decrease and surface activity is enhanced as the length of carbon chain increases. The surfactants with tetradecanoyl and hexadecanoyl groups show a good foaming property and especially, the long-chain acyl-serine performs better. These are all related to the hydromethyl group in the serine.