Synthesis, Performance And Application Of Palmitoylmethionine Surfactant

Amino acid surfactants are a class of amino acid based green surfactants with excellent surface properties.Amino acid surfactants are not only excellent in surface properties,but also mild and non-irritating,good in skin-friendly,fine in foam,strong in antibacterial ability,excellent in biodegradability and biocompatibility.Thus,amino acid surfactants are widely used in cosmetics and biomedicine.In this paper,palmitoyl methionine surfactant(C₁₆PMS)was synthesized and its optimal synthesis process was explored.And then the properties of C₁₆PMS and cocamidopropyl betaine?CAPB?complex system were studied and the rule of law theory was used to verify the synergy of the complex system.Besides,new groups were introduced into C₁₆PMS to obtain palmitoyl methionine sulfoxide surfactant(C₁₆PMSO).Finally,the rheological properties of the C₁₆PMSO and CAPB complex system were explored.The specific research contents were as follows:1.The C₁₆PMS was synthesized with natural palmitic acid and methionine by acyl chloride reaction and amidation reaction.The influences of reaction temperature,molar ratio of reactants,reaction medium volume ratio and reaction time were investigated on the amidation reaction by single factor experiments method.In addition,the structure of the product was characterized by FTIR?¹HNMR and Mass spectra,and the properties of the product were investigated.The results showed that the optimum conditions of amidation reaction were screened out as follows:reaction temperature of 30?,the molar ratio of reactants 1:1.2,the volume ratio of reaction medium 1:2,and the optimum reaction time 2.5h.Under the above conditions,the product yield was 89.00%.And the result of the characterization was the target product.Furthermore,the critical micelle concentration?CMC? and surface tension??? of product were 1.2×10^-4mol/L and 29.59mN/m,respectively.Besides,the emulsification performance of the product was better than the commercially available lauroyl glutamic acid surfactant?LAS?.The order of emulsifying properties of different oil phases from large to small were benzene,toluene,liquid paraffin,chloroform,carbon tetrachloride.The product had good solubilizing performance,and its solubilization ability of benzene was 6000mL/mol.The foam performance of the product was significantly higher than LAS.2.The surface activity of complex systems with different compound ratios of C₁₆PMSO and CAPB was explored.The regular solution theory was used to verify the synergistic effect of the compound system and the optimal compound ratio.Furthermore,the effects of alcohols and inorganic salts on the surface activity of the compound system were investigated.The results showed that there were synergistic interactions between C₁₆PMS and CAPB.The surface activity of the compound system was the best when the molar ratio of C₁₆PMS and CAPB was 4:6.In addition,the critical micelle concentration and the surface tension reached 0.0567mmol/L and27.63mN/m,respectively.The theoretical calculation showed that compound system's interaction parameter??_m? and the maximum adsorption amount of gas/liquid surface were-3.66 and6.23?mol/m.Moreover,addition of an amount of inorganic salts and alcohol into the complex system can increase its surface activity.When the mass concentration of sodium chloride was 6g/L,the surface activity of the compound system was excellent.The synergistic effect of Mg²⁺ on the compound system was greater than Na⁺.And the surface activity of compound system was the best when the mass concentration of N-butanol was 2g/L.The synergistic effect of the hydroxyl number of the alcohol on the compound system from large to small were butanediol,N-butanol.But Al³⁺and butanetriol had antagonistic effect on the compound system.3.The C₁₆PMSO was synthesized from methionine and palmitic acid by three-step method and the influences of single factor on amidation were investigated.Then the structure of the target product was characterized by FTIR,¹HNMR and MS and the application properties of the product were studied.The results showed that the optimum conditions of amidation reaction were screened out as follows:reaction temperature of 30?,the molar ratio of reactants 1:1.2,the volume ratio of reaction medium 2:1,and the optimum reaction time 4h.Under the above conditions,the product yield was 86.72%.Furthermore,the CMC and surface tension??? of product were 2.6×10^-4mol/L and 35.20mN/m,respectively.Besides,the foam performance,wetting and antibacterial properties of the product were significantly higher than LAS.4.The facial cleanser formula was designed after studying the synergistic effect of C₁₆PMSO and CAPB compound system and the influences of AEO₉ mass fraction,NaCl content and pH value on the rheological properties of the compound system.The results showed that the surface activity of the compound system was the best when the molar ratio of the compound system was 4:6,and the CMC and the surface tension reached 0.18mmol/L and 29.65mN/m.The theoretical calculation showed that?_m was -2.06.The viscoelasticity and spreadability of the compound system were excellent when the AEO₉ mass fraction was 2%,the NaCl mass fraction was 1.4% and the pH was 5.6.Based on the results showed above,facial cleanser was prepared.The senses and physical and chemical indicators of facial cleanser all met the GB/T 29680.