Synthesis And Application Of Switchable Surfactants Bearing Amidine Group

The surfactants are hoped to get away from the system or loss their surface activities after they finish their function,and switcbable surfactants can be used to address this problem.Switchable surfactants are those can change their molecular structure through certain chemical or electrochemical methods so as to alter the bulk solution surface acitvity greatly(20mN/m).Here we report the synthesis and charactefizaion of switchable surfactants bearing amidine group.Octylamine,Decylamine,Dodecylamine,tetradecylamine and hexadecylamine N,N-dimetylacetamide,dimethyl sulfate are used to synthesize a series of long-chain alkyl amidine tertiary amine compounds that can be reversibly transformed into bicarbonate surfactants by reacting with dry ice.The best synthesis condition is studied as follow: Chloroform is used as solvent,phosphorus trichloride as dehydrating agent and pH regulator, feed ratio 1:3,at about 70℃.Switchable properties are studied by emulsification and demulsificaion:the emulsification and demulsificaion function are better as the hydrocarbon chain decreased and the N′-dodecly-N,N-dimethylacetamidinium bicarbonate has the best emulsification and demulsificaion function.A novel double-tailed cationic surfactant,N,N′-didodecylacetamidinium bicarbonate,is prepared by reacting dimethylacetamide dimethyl acetal with dodecylamine,followed by reacting with dry ice.MSD,FTIR,¹H NMR,¹³C NMR,2D-NMR are used to confirm its structure.The surfactant reduces the surface tension of pure water to 24.69mNm^-1and its critical micelle concentration is 8.75×10^-5M.Formation of vesicle is also observed by TEM.A novel cationic polyacrylamide flocculant bearing amidine group is synthesized using acrylamide,N,N-dimetylacetamide and dimethyl sulfate.Temperature,feeding ratio, monomer content,initiator amount are considered for molecular weight using orthogonal test.Flocculantion effect is also studied:Flocculant with high N′-acrylamide-N,N-dimethyl amidine content and high molecular weight has better flocculantion effect.