| Rosin,a kind of natural and renewable resources,is extremely abundant in China. However,the deep processing ratio of rosin now in China is comparatively low.Therefore,the exploitation of deep processing of rosin to increase its commodity additional value is a significant research project worthy of carrying out deeply.In this paper,five quaternary ammonium gemini surfactants containing modified rosin were synthesized,which aims at the exploitation of novel fine chemical products of rosin and the investigation of a new path for the deep processing of rosin which is extremely abundant in Guangxi,China.1.Five types of quaternary ammonium gemini surfactants containing modified rosin, N,N-dimethyl-N-dehydroabietyl-N,N'-(1,3-propylene)diammonium dibromide(Ⅲa), N,N-dimethyl-N-dehydroabietyl-N,N'-(1,4-butylene)diammonium dibromide(Ⅲb), N,N-dimethyl-N-dehydroabietyl-N,N'-(1,6-hexylene)diammonium dibromide(Ⅲc), N,N-dimethyl-N-dehydroabietyl-N,N'-(1,3-(2-hydroxide)propylene)diammonium dichloride(Ⅲd)and N,N-dimethyl-N-dehydroabietyl -N,N'-(p-xylene)diammonium dibromide(Ⅲe),were synthesized in acetonitrile solvent by refluxing the intermediate N,N-dimethyl dehydroabietylamine(DMDA)with 1,3-dibromide propane,1,4-dibromide butylane,1,6-dibromide hexylane,epichlorohydrin,p-xylene dibromide respectively.DMDA was prepared by dehydroabietylamine,formic acid and formaldehyde.The optimum synthetic conditions were identified by the mono-factor experiments and the orthogonal experiments, which were confirmed by stability experiments.The structures of the products were characterized by elements analyzer,FT-IR,1HNMR and 13CNMR spectroscopy.2.The physicochemical properties of the five surfactants were determined all-sided. The results show that they possess better surface activity as compared with DTMAS, DDMBAC and CTAB.We also investigated the solubility properties of the five surfactants in water and familiar organic solvents.3.Aggregation numbers of micelle(N)of five quaternary ammonium gemini surfactants containing modified rosin were determined by steady-state fluorescence probe method in which pyrene was used as fluorescence probe and cetylpyridinium chloride(CPC) as quencher.According to the change of fluorescence intensity ratio of pyrene I1/I3 with the change of surfactant concentration,Critical Micelle Concentration(CMC)was investigated by steady-state fluorescence probe.The values were consistent with ones tested by surface tension method in principle.Satisfactory results of aggregation numbers of Critical Micelle Concentration(Nm)were obtained when the solutions of surfactant were prepared with saturated aqueous solution of pyrene and the optimum concentration of CPC were selected in 0.04～0.06 mmol·L-1.The experimental results show that N increases linearly with the increase of surfactant concentration in the range of 5～15 times of CMC and Nm can be extrapolated from N-C curve:10,16,20,19 and 22,respectively.4.The inhibiting performance and adsorption behavior of five quaternary ammonium gemini surfactants containing modified rosin on mild steel in 1mol/L HCl solution were studied by weight loss and electrochemical measurements.The inhibition efficiency increases with an increase in the tested surfactant concentration before which reaches 0.2g/L,but decreases a little with an increase in temperature.The adsorption processes of the surfactants on the surface of mild steel are automatous and exothermic processes and belong to physical adsorption.The results indicate that the five surfactants are excellent mixed-type corrosion inhibitors for mild steel in hydrochloric acid.The inhibition efficiency of the surfactants at 0.2g/L(2.25～2.65×10-4mol/L)decrease as follows:Ⅲe＞Ⅲa＞Ⅲb＞Ⅲc≈Ⅲd.
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