Systhesis And Tribological Properties Of Gemini Compounds Containing Nitrogen And Sulfur

A Gemini Surfactant consists of two conventional surfactant molecules chemically bonded together by a spacer in a hydrophilic head group or a place close to the head group. Because of its difference with the common single-chain surfactant structure, Gemini surfactants exhibit a higher surface activity. Gemini surfactants can’t be accept in industrial applications because of its expensive and difficult to synthesize.In order to expand New application of Gemini surfactants, Gemini surfactants containing active element S and N were prepared in this paper. The tribological properties of the synthesized Gemini surfactants as additives in PEG400was evaluated.Firstly, N,N’-Didodecylthiourea can be obtained in the reaction of dodecylamine and carbon disulfide in methylbenzene. The effect of reaction conditions on the synthesis of N,N’-Didodecylthiourea was investigated by method of experiments.The results show that the yield of N,N’-Didodecylthiourea is91%under the following reaction conditions: the molar ratio of dodecylamine to carbon disulfide was2.0:1,and the reaction was effected for10h at reflux temperature;The chem. Strctures of the prepd. compds. were characterized by FTIR、1H-NMR spectra and elemental anal. The critical micelle concentration (CMC) and surface tension was measured as4.8×10-4mol·L-1and42.5mN·m-1, Results showed that N,N’-Didodecylthiourea exhibits a certain surface activity.And then N,N’-Didodecylethylenediamine containing N was prepared by using ethylenediamine and1-bromododecane in n-propanol. The effect of reaction conditions on the synthesis of N,N’-Didodecylethylenediamine was investigated by method of experiments.The results show that the yield of N,N’-Didodecylethylenediamine is45.5%under the following reaction conditions:the molar ratio of1-bromododecane to ethylenediamine was2.4::1,and the reaction was effected for8h at reflux temperature;The chem. Strctures of the prepd. compds were characterized by FTIR、1HNMR spectra and elemental anal. The critical micelle concentration (CMC) and surface tension was measured as6.8×10-4mol·L-1and31.61mN·m-1, Results showed that N,N’-Didodecylethylenediamine exhibits a certain surface activity.In order to expand new application of the pred Gemini Compounds, their tribological properties in polyethylene glycol400as lubricating additives were evaluated using a four-ball tester. The results showed:In particular, the introduction of N,N’-Didodecylthiourea can lead to an increase in the load-carrying capacity of the PEG-400from696N to1577N; the wear scar diameter is reduced from0.35mm to0.22mm. presenting good application prospects as lubricant additives.And N,N’-Didodecylethylenediamine can lead to an increase in the load-carrying capacity of the PEG-400from696N to862N; No significant effect on reducing the wear scar diameter and the friction coefficient. Compare the tribological properties of these two Gemini Compounds, N,N’-Didodecylthiourea shows a good Lubricating properties.