Synthesis And Properties Of Amino Acid And Imidazole-based Zwitterionic Surfactants

Imidazole-based zwitterionic surfactant belongs to both ionic liquid and the field of surfactant,it has attracted more and more attention because of the unique structure and properties.In order to optimize the synthetic routes,and explore the relationship between molecular structure and performance,three different types of imidazole-based zwitterionic surfactants are designed and synthesized in this paper.Including 2-(3-methylimidazol-1-yl)succinic acid monoalkyl ester(CnMimSU,n=8,10,12,14,16),2-(3-dodecylimidazol-1-yl)succinic acid monoalkyl ester(CnDimSU,n=1,2)and 2,2'-(3-methylimidazol-1-yl)bis-succinic acid monoalkyl ester([MimSU]2Cn,n=10,12).The molecular structure of each product is confirmed by infrared spectroscopy and nuclear magnetic resonance.In addition,the effect of hydrophobic alkyl chain length on the application performance and surface activity of CnMimSU(n=8,10,12,14)has been investigated.Amino acid zwitterionic surfactant which has many excellent properties,such as safety,mild,low irritation,environmentally friendly and so on,can be utillzed in daily chemical products,food,medicine and other fields.However,several defects have restricted its development,such as complex synthetic routes,high raw material costs and difficult post-processing.In addition,only a very few papers have reported the relationship between its structure and properties.To address these issues,five kinds of new amino acid surfactants named 2-dodecylamine succinic acid monoalkyl ester(CnDamSU,n=1=2,3,4,6)are designed and synthesized in this paper.The molecular structure is confirmed by FT-IR and 1H NMR,the application performance and surface activity of CnDamSU(n=1,2,4,6)have been studied.(1)Bola imidazolium-based zwitterionic surfactants named 2,2'-(3-methylimidazol-1-yl)bis-succinic acid monoalkyl esters([MimSU]2C10,[MimSU]2C12),and two other kinds of surfactants based on N-dodecyl-imidazole called 2-(3-dodecylimidazol-1-yl)succinic acid monoalkyl ester(C1DimSU,C2DimSU)are synthesized.The molecular structure of intermediates and final products is characterized by 1H NMR.(2)Five kinds of imidazolium-based zwitterdonic surfactants with different length of alkyl chain,2-(3-methylimiciazol-1-yl)succinic acid monoalkyl ester(CnMimSU)are synthesized.The influence of hydrophobic alkyl chain on the properties of CnMimSU has been analyzed It is found that C12MimSU has the best foam performance,the emulsifying ability of CnMimSU enhances with the increase of carbon chain length,the wettlng power of C14MimSU is the best,the calcium soap dispersibility of CnMimSU improves with increasing the value of n.Also,as the number of carbon atoms in the side chain goes up,the surface tension(?CMC),critical micelle concentration(CMC)and minimum molecular cross-sectional area(Amin)decrease,but the surface pressure(?CMC),maximum surface excess(?m),adsorption efficiency(pC20)and the value of CMC/C20 increase.Meanwhile,the relationship between log CMC and n follows the Stauff-Klevens formula.(3)A series of novel ester-containing amino acid surfactants,2-dodecylamine succinic acid monoalkyl ester(CnDamSU)are synthesized,and their application performance and surface chemical properties are researched.The results show that C2DamSU has the best foaming property,the foam stability and wettability of C4DamSU are more excellent than others,and CJDamSU shows outstanding emulsifying ability and calcium soap dispersibility.With the length of hydrophobic chain increasing,the values of CMC/C20,?m,pC20 and ?CMC increase,but the values of ?CMC,Amin and CMC decrease.The trends of these parameters indicate that the surface activity of CnDamSU increases with the number of carbon atoms in the side chain increasing.