Study On Syntheses And Properties Of Sodium N-octadecye Itaconamate Surfactants

In this paper,four new sodium N-octadecyl itaconamate surfactants were synthesized using itaconic anhydride(IAn)and long chain aliphatic amines(such as octadecylamine,hexadecylamine,tetradecylamine and laurylamine)as the raw materials through both amidation and neutralization processes.The preparation and properties of the surfactants were studied to obtain a new class of environmentally-friendly surfactants so as to reduce their dependence on the use of fossil materials,thus to protect the environment.First,N-octadecyl itaconamic acid NIC-18 was synthesized by IAn and octadecylamine as raw materials through amidation.Then the sodium N-octadecyl itaconamates(SNIC-18)was synthesized by NIC-18 and sodium hydroxide(NaOH)through neutralization process.The optimum process conditions of NIC-18 were determined by single factor tests and orthogonal test.The optimum synthetic conditions were as follows:the amidation reaction was carried out with the condition of n(IAn):n(octadecylamine)=1.10:1,at 25°C for 35 minutes.Based on the synthesis process,a series of intermediate products,NIC-16,NIC-14 and NIC-12were synthesized by changing the numbers of carbon atom of the long chain aliphatic amines.And their structures were characterized by Nuclear Magnetic Resonance(~1H NMR)and Infrared Spectrometer(FT-IR).Then,the surface tension,critical micelle concentration(CMC),foaming property,Krafft point,wettability and emulsification property of the surfactants were determined.The results showed that the surfactants had low Krafft points,good solubilization,excellent wettability,good foam property and emulsifying ability.In addition,the effects of inorganic electrolytes on CMC values and surface tensions of SNIC-n(n=18,16,14,12)surfactants were systematically studied.The effects of inorganic electrolytes concentration and types of anions and cations on CMCs of SNIC-n were investigated.The results showed that the CMC values of SNIC-n surfactants decreased gradually with the increase of inorganic salt concentrations,and the ability of decreasing the CMC values of SNIC-n surfactants was ranked as NaCl>NaBr>NaI.The CMC values of SNIC-n surfactants with the same concentration of LiCl,NaCl or KCl decreased gradually,and the ability of decreasing CMC of SNIC-n was ranked as KCl>NaCl>LiCl.On the basis of the properties of SNIC-n surfactants studied,the synthesized SNIC-n and nonionic surfactants(OP-10)were mixed.The surface tension and CMC were studied.After mixing with OP-10,the CMC value and surface tension were significantly decreased,and the surface activity was improved.