氟化季铵盐表面活性剂的合成及其表面活性

Synthesis and Surface Activity of a Fluorinated Quaternary Ammonium Salt Surfactant

以三氟乙酸乙酯和N,N-二甲基乙二胺为原料,经酰化反应制得中间体NDAET;然后将NDAET与溴代十二烷发生季铵化反应得到氟化季铵盐表面活性剂N,N-二甲基-N-{2-[(2,2,2-三氟乙酰基)氨基]乙基}-1-十二烷基铵溴化物(NDAET-12)。通过FTIR、13CNMR、1HNMR对其结构进行了表征。考察了反应物物质的量比、反应时间、反应温度、溶剂用量对NDAET-12产率的影响。在单因素实验的基础上,采用正交实验对NDAET-12的合成工艺进行了优化。NDAET-12的最佳合成工艺条件为:n(NDAET)∶n(溴代十二烷)=1.0∶1.3,NDAET质量为2.76g,反应时间12h,反应温度90℃,溶剂用量为20mL。在该条件下进行平行验证实验,得到NDAET-12的平均产率为86.75%。热重分析表明,NDAET-12是一种热稳定性较好的表面活性剂。对NDAET-12的临界胶束浓度(CMC)、表面活性和乳化性能进行了测定。NDAET-12的CMC为0.8 g/L,γCMC=25.15 mN/m,表面活性较好。与十二烷基三甲基溴化铵(DTAB)和十六烷基三甲基溴化铵(CTMAB)相比,NDAET-12从乳化体系中分出10mL所需要的时间最长,为473s,具有优异的乳化性能。

N-[2-(Dimethylamino)ethyl]-2,2,2-trifluoroacetamide(NDAET) was synthesized by acylation between ethyl trifluoroacetate and N,N-dimethylethylenediamine. Then, it reacted with 1-bromododecane to obtain a fluorinated quaternary ammonium salt surfactant, 1-dodecyl ammonium NDAET-12. The structure of the product was characterized by FTIR, 13 CNMR and 1 HNMR. The effects of raw material molar ratio, reaction time, reaction temperature and solvent dosage on the yield of NDAET-12 were investigated by single factor experiments. Subsequently, the synthesis process of NDAET-12 was optimized by orthogonal test. The optimal synthesis conditions of NDAET-12 were obtained as follows: n(NDAET) ∶n(bromododecane) = 1.0∶1.3, 2.76 g NDAET, reaction time 12 h, reaction temperature 90 ℃, solvent dosage 20 mL. A parallel verification experiment was carried out under the above-mentioned conditions and NDAET-12 achieved an average yield of 86.75%. Thermogravimetric analysis showed that NDAET-12 was a surfactant with good thermal stability. The critical micelle concentration(CMC), surface activity and emulsifying properties of NDAET-12 were measured. The CMC of NDAET-12 solution was 0.8 g/L and the surface tension γCMC was 25.15 mN/m. Moreover, NDAET-12 exhibited good surface activity. Compared with surfactants DTAB and CTMAB, NDAET-12 took the longest time to separate 10 mL of water from the emulsion system, 473 s, indicating that NDAET-12 had excellent emulsifying properties.