Research On The Synthesis And Properties Of Amino Acid-based Surfactant Which Is Derived From Silk Fibroin

Amino acid-based surfactant has good biodegradable and security. Silk fibroin is rich in amino acids; silk peptide and the amino acids were prepared from silk fibroin through the processing of hydrolysis, purifying and concentrating, which can be used for the synthesis of amino acid-based surfactant. So, the study is important to increase the utilization rate of silk fibroin and develop a new environmental friendly surfactant.In this paper, the sodium fatty acyl amino was synthesized by two steps from fatty acyl chloride and amino acid. In the process, by the study of the optimum conditions of synthesizing the sodium lauroyl alanine, the optimum conditions of the sodium fatty acyl amino were obtained as follows: mixed solvent of water-acetone, the volume ratio of water︰acetone was 4︰6, the molar ratio of amino acid︰fatty acyl chloride was 2︰1, pH was 9, reaction temperature was 20℃, reaction time was 4h. Under these conditions, the yield of SLA was 87.5%. They were characterized by IR,1H NMR and amino acid analysis.On this basis, the sodium fatty acyl silk amino or silk peptide were synthesized by two steps from fatty acyl chloride and silk amino, silk peptide. The mixed solvent of water-acetone was used and the optimum conditions of the sodium fatty acyl amino were obtained. Then, they were characterized by IR and amino acid analysis.In this paper, some surface properties of these surfactants were studied. Such as, surface tensions were determined by slice method, and some physical chemistry parameters such as cmc,γcmc,Γm, Am andΔG_ps⁰ were calculated. The results showed that all the surfactants had excellent surf activity. In the homologous compound of surfactant,ΔG_ps⁰ decrease and the trend of micelles formation intensify when the number of carbon increase. For the homologous compound of the sodium fatty acyl glycine and alanine, the trend of cmc is accord with the formula lgcmc = A - Bm as the change of chain length. Foam properties were tested by Ross-Miles method. The experiment results showed that all the surfactants had excellent foaming ability and foam stabilizability.The effects of a high molecule polymer to a surfactant solution were investigated by means of surface tension. The results showed that there were some interactions between surfactant and non-ionic polymers, the apparent cmc of surfactant solution increase when the polymer added, and the apparent cmc as increased as the concentration of the polymer increased. The effects of a polymer electrolyte CMC to the surface tension of the surfactant solution are unobvious.